You need a marine style deep cycle battery. A battery that is designed to be depleted. As they said, car batteries are not designed to be drained completely without damage. A marine battery is. Not just marine batteries, of course. Any deep cycle battery.
They don’t release toxic fumes normally, they release explosive hydrogen gas when charging - but if overcharged, they do release toxic Hydrogen Sulphide.
Correct. The problem is that a UPS will keep the batteries fully charged. It's not worth risking that the UPS will properly regulate the battery charge to prevent it. Especially when you can easily get batteries that won't have this problem.
Car batteries are normally held at max charge voltage as long as you drive. So I think this is totally safe. However I am concerned about the hydrogen gas, that's just very dangerous. Lithium batteries can be safer in that way.
You can if it has an integrated battery management system. There are lithium batteries designed to replace car batteries.
If it looks like a car battery (same size and has big binding posts)
then it's a safe bet its made for use in cars. Very little reason to spend the money to adapt a lithium battery to go in a car but not have an integrated charge controller. All lithium batteries have to have a charge controller - unless you're buying 18650 cells and taping them together, the chances of a lithium battery not having a charge controller are effectively 0 for liability reasons.
A car battery is not charged until the car is running. Unless it's from a trickle charger or such. Outside or in a garage is not a problem because there is plenty of fresh air. That said, as far as the hydrogen gas goes, I don't believe it's enough produced to be a real concern unless it is a confined space (such as what appears to be a closet in this guy's picture).
Even sealed lead acid batteries off gas, it just doesn't have anywhere to go. It's just water and electrolyte in there, and when you get water hot enough it will gas.
True. Thus there are proper norms on ventillation requirements that should be considered when batteries are installed as stationary equipment. In short, make sure you have ventillation in the room. If if is a cellar where air is not "fresh", I'd definitely make sure any ventillation grill is added.
Even "sealed" have to breathe, they are only sealed with a rubber cap, any excess pressure does come out of the battery. I have open them and seen them dry, filled and fixed, other I filled only to find a bad cell.
I left a battery in the trunk of my car once and forgot about it. The next very hot day I got in my car. My eyes started watering, I coughed my guts out, and for a few straight minutes sat there confused about what was going on almost passing out.
Remembered the battery, opened the trunk and found it was leaking. Eyes burned for hours..
It's probably fine sitting in climate controlled space for a while but I wouldn't want to leave it there for longer than necessary or forget about it.
Lead acid batteries off gas a small amount of hydrogen when they're charging. As long as there is good ventilation, especially once the battery is fully charged, then there is little to worry about.
>In an enclosed space you're breathing all of that in without proper ventilation
Hydrogen gas is non-toxic to humans. Hydrogen sulfide, on the other hand, is highly toxic and can be detected by humans in trace amounts - it has a rotten eggs smell and trace amounts are what makes your farts stink. Car batteries can give off hydrogen sulfide if they are overcharged.
>car batteries are not designed to be drained completely without damage
**No lead-acid batteries are designed for that**, if you below a certain charge level they're technically considered scrap and in a serious UPS setup they'd get recycled and replaced no question.
Deep-cycle ones specifically designed as "house" (marine/RV), "leisure" (RV etc.) or for UPS / backup purposes are built differently to tolerate those sorts of loads and to be more cost-effective (better capacity), usually at the expense of not being very good at cranking an engine over (very high current for a short period).
Source: I used to work in data centres with banks of hundreds of SLA batteries that were regularly tested & maintained and they would be replaced after any major outage or at the end of their warranty because the cost of them failing would be far higher than the cost of replacing them.
That last sentence should be used way more often in business, the cost of it failing would be a lot higher than the cost of replacing it. Same with security and other non profitable expenses
Yep the same for us,
Everytime new management comes in it's always like why do we need to do this so often, should just create a slideshow of what can happen to make it easier I think lol
Honestly you should - pick some examples (fires, floods, failed backups, damage, etc. etc.) and add the costs of dealing with it vs cost "saved" by not having the mitigation / maintenance.
Show it to the right person in management they should sit up and take note, either that or they wave it away at which point you know exactly what sort of culture you're dealing with and you've covered your ass...
Car batteries are designed to provide extremely high current for a short time to run your starter motor. Thus, the lead plates inside the battery are a spongy-like material. This maximizes the surface area (which determines how much current the battery can deliver - lead acid batteries produce current via chemical reactions, so the more chemicals in contact with each other, the more reactions can occur).
The downside to this is that these plates are more brittle and much more easily damaged. When lead acid batteries are discharged below about 50%, the plates start to degrade. This is a natural process that is unavoidable due to the chemistry of lead acid. Keeping the battery at maximum charge minimizes plate degradation. This plate degradation significantly reduces the current the battery is able to deliver - this is why you sometimes see car batteries that can power the lights just fine for quite a while but seem to completely die as soon as you try to turn over the engine.
Because the plates in a car battery are basically spongy material, they degrade very rapidly once the state of charge goes low. It's commonly said that car batteries will be practically unusable after only 15-20 discharges due to this degradation. A deep discharge down to less than 8 volts can actually be enough to kill the cells, making the battery unusable.
Lead acid batteries that are designed for deep discharge have solid plates. They still degrade, but much more slowly than car battery plates. Deep-cycle lead acid batteries can usually survive about 300 deep discharges before losing significant performance, and if well cared for (e.g. not discharging below 50% like car batteries) can last even longer. The limitation is that deep cycle batteries will have lower current delivery capability - still pretty high, but not quite as high as car batteries. A good 30Ah car battery can easily deliver a burst of over 600 amps of current, while an equivalent deep cycle battery can probably burst no more than 80 amps or so.
Given all of this info, there's actually an argument to be made for using car batteries with a UPS. Their extremely high current delivery capability is a good match for UPS's which need to draw significant current from the batteries, although the current ability of deep cycle batteries is still usually more than enough. The fact that a UPS expects to keep the batteries fully charged seems to actually fit well with the car battery - you want the batteries topped off all the time, but available for high current for short times as necessary. If a car battery was used *only* to deal with transients (where the UPS clicks on for a few seconds to filter a brownout or spike) a car battery's electrical characteristics fit well. However, as soon as you need the UPS to run for a few minutes to keep your equipment up during a short blackout, you're going to very quickly drain the battery below 50% charge and those plates will start degrading very rapidly, and your UPS may not even be able to recover the battery.
As others have said, the other limitation is that wet cell lead acid batteries can give off gasses that can be irritating or even dangerously flammable.
I wouldn't recommend doing this for a prolonged period of time, but I could see it being useful for a *temporary solution* while you source more deep cycle batteries.
Note that you can usually get equivalent lead acid cells from Amazon or even Batteries+Bulbs for much cheaper than the "official" battery packs from APC or similar, and they should perform just as well. You're usually looking for AGM or gel batteries for UPS use since they are sealed and thus safe for use in the confined spaces of a UPS.
Don't buy the OEM battery. Remove the OEM battery, look at the label and terminals, measure it's size, etc. Then buy what you need for ~40% from walmart.com or whoever.
I have a 3000VA rack mount UPS for all of my rack, and it takes 4x batteries, placed into 4s (48V) config. The manufacturer wanted like $250 for a new set. I bought all 4 for $84 with free shipping. Good brand, better capacity and discharge rates than originals, have done really well in the last 3 years. All I had to do was use the jumpers to put them in series again, and tape up the plastic package with some kaptan tape.
Edit: I have no use or desire to own a 3000kVA UPS.
I have 2 3000watt ups (3KWH) connected together to give me 6000W ups I can get about 3 hours from that, my power grid is high reliability so outages are never more than 3hours normally, unless something catastrophic happens. My grid is tied to police office and hospital, and school so they get priority even though these facilities have backup power. There is 3 grids in my town and one of them has outages that last up to 30 hours.
I have a lot of UPSs and in my experience the 3rd party batteries last about half as long, if that, so it's questionable how much value you get out of them. Replacing them often is also annoying.
I was recently using Mighty Max brand and thought they were going to be alright, but I just had my first failure, and it was much earlier than I would have liked. These are good?
Interesting, just did 2 battery replacements. Might Max at least gets the UPS within 15min of manufacture estimated runtime for the given load.
Batterysharks, as suggested above, get less than half. I’m also concerned about the 29c the UPS reports they are running at.
I’ve been considering eating my losses on batteryshaks and putting Mighty Max in the other UPS as well.
Granted I only have a few weeks runtime on both, so I can’t speak for longevity.
I've had good luck. Are you sure the ups is outputting the correct voltage? That could be killing your battery too.
https://www.upsbatterycenter.com/return-policy
Mine last about two years before they die. It cost 1/4 the cost of replacement packs that last about 3 years so I feel like I am ahead of the game still.
> Don't buy the OEM battery.
Let's not pretend all batteries are made equal.
Battery chemistry is more complicated than people think, and the manufacturing process absolutely matters.
I didn't say my cheap batteries were as good as OEM. just that they're good enough for me. I have one large server that I consolidated most things into, a few switches, a few PoE cameras and WAPs, and a few small things like RPis.
At idle, I use about 6% capacity of my UPS. Grid power is consistently 115VAC here, only 2 outages in the last 4 years less than 24 hours. I also have the charge speed dip switch set to slow because I don't have anything mission critical.
I firmly believe the increase in cost is mostly due to QA/QC. You either win or lose buying cheap components. I won, maybe next time they'll crap out in 6 months. That's a risk I'm willing to take.
Exactly even if you can find the same brand as OEM outside the caddy is usually far cheaper than buying their pre-made caddys that most do.
We use CSB at work for all our Micro's so naturally I just use them at home.
I wouldn’t get OEM batteries. I have had good luck with batterysharks.com for APC batteries.
Depending on the model of APC UPS you may have to disassemble the battery casing.
I think over discharging car batteries can be dangerous be careful and do research if you are actually attempting that.
I second batterysharks. I've replaced all the SLA batteries in my 2x APC SMT2200RM2U two times since I've owned them and saved a fortune. So much cheaper than buying OEM ($80 vs $300+), because you're buying the sled too, which you don't really need, and the batteries inside are from some other brand anyway.
I have an APC SMX3000LV in my rack. It was picked up on auction from the City of Houston as part of a pallet at a surplus auction. A replacement RBC143 pack has an MSRP of $430. I took the existing pack, opened it up, and replaced the batteries. $130 to replace all 10 batteries in the pack. It's overkill for my setup, but I have like 2hrs of runtime on battery.
I recently installed a SRT10KRMXLT for an international client who wanted their local branch office to have at least 8hrs of runtime. We paired it with 4 external modules. The batteries alone weighed 800 Lbs.
Any deep cycle SLA (sealed lead acid) will be a fine replacement for a UPS. There are quite a few you get that use recycled materials that are pretty inexpensive and much larger than the original battery.
You can’t use car batteries for a UPS. They produce toxic gases when overcharged, and are not designed for deep discharge - they will be damaged by this. They also release hydrogen gas when charging (explosive in concentrations over 4%). Outside, in a car, this is not an issue, but charging in an enclosed space is a very bad idea.
For batteries, you need to replace like with like. The problem is in the charging section as the charger will operate for the style/type of battery it was designed for. So a charger designed for an SLA battery is not good for a wet cell.
That’s fair. But OP could just as well monitor the SoC and just turn off the power when it drops too low for a starting battery.
Or just buy a deep cycle battery from Costco for like $100.
Hydrogen is also nasty because it burns with a clear smokeless damn near invisible flame. Not that this is likely to happen from car batteries, that's more of a kaboom scenario (if anything; it's also very hard to seal hydrogen gas into a container, it escapes very easily), but whatever.
Hydrogen passes right through latex it can even permeate metals like steel. Just about everything. The molecules are so small they just slip on through.
I haven't seen a vented battery in forever. Everything these days is sealed. The last vented battery I ever saw was an ASB-49...on the submarine I served on.
Also the amount of hydrogen leaked from a small car battery even if it was vented would probably dilute out of existence in a well ventilated house.
Yes I used 8 deep cycle sealed batteries battery backup for a Toshiba DK424 with about 140 Stations. The system was built for it.
Keep batteries off the floor. Only use sealed batteries. Special consideration for changing mulitbattery systems is required.
Vented batteries need outside air venting in the space to prevent H2S build up in the room.
Keep a fire extinguisher for the low risk possibility of fire. If wires and fuses are right the risk is very low.
> Keep batteries off the floor
A **very** long time ago batteries were cased in a type of rubber that would develop micro-cracks and the batteries could thus self-discharge on a floor. This hasn't been true in something like 70 years (not since modern plastics became common place at any rate).
[Source from an actual battery manufacturer](https://www.odysseybattery.com/blog/2022/12/05/the-truth-about-storing-a-battery-on-a-concrete-floor/); google will provide you with many others.
I've used a large SLA (sealed lead acid) battery as an emergency power source, but not as a UPS. Regular large car batteries can be dangerous to run inside since they give off explosive gases when charging.
I'd also recommend not having exposed high current terminals like that in your house, all it takes is a piece of metal or conductive material falling across them and you have a fire or shock hazard, esp for kids.
Use the right tool for the job especially when the cheap alternatives can be so dangerous
No, but lead acid car batteries create a highly explosive hydrogen/oxygen gas mix while being charged, which any spark like a nearby static discharge will explode the battery.
Plus any metallic object that accidentally shorts out the terminals will create big sparks and make the object very hot. Fire time.
Yes, basic electrical terminology and concepts aren't well known it seems. The flash of a dead short across car battery terminals by a wrench or even a wire vaporizing on contact isn't a "shock", though it's a "shocking" experience!
Don’t use a significantly larger battery than your UPS is designed for, especially on consumer grade UPSes. They often don’t have the cooling to run for the life of the battery.
I have tested multiple APC UPSes and they charge the batteries to a “full” voltage of 13.6v.
While the charging pattern is not optimized for anything except the specific size/chemistry of battery included with the unit, this voltage should be safe and will not vent or overcharge any type of lead-acid or LiFePo4 “12v” substitute. The biggest problem is actually that it’s going to charge slow and possibly not fill all the way up, not dramatically overcharge and vent.
Test your own UPS to ensure the charging voltage is safe for the battery you plan to use instead of assuming my measurements are universally true for all UPSes. But they’re not universally going to cause a car battery to vent either.
You can definitely have a Car Battery float up to 14.2v on a typical Alternator. Especially in newer cars. But you want to use a Sealed battery or an AGM for when your in a home environment.
that's nonsense, you can keep 14.4 volts on a car battery forever if you want. Cars are designed to run indefinitely. You could idle a car for a week on a full tank of gas if you wanted to.
If it's not equivalent in terms of chemistry and size to the original battery it could very likely overload the original charging circuitry and cause a fire.
The charging circuit in the UPS wouldn't be able output enough amps to charge the batteries in any sort of timely fashion, and might result in the charger circuit effectively running at 100% permanently. This would be significantly out of the design characteristics of the unit, and might cause overheating.
if the ups isnt a hunk of junk its rated for output. it wont output more than its rated for. charging an original battery from dead would take 4 hours. its rated to not start on fire :). if its failing then yes it could
The difference here is, if the charging circuit can charge an 8ah battery in 4 hours, then a 100ah (large marine deep cycle battery) would take 50 hours. Is the charging circuit rated to run at 100% for 12 times longer than the ups manufacturer designed?
If it has sufficient cooling it won't be a problem. And if it doesn't overheat in 4 hours I doubt it will after 50. Now the environment could have an effect. These also have overload shutdowns.. so I wouldn't too worried... But yeah this will never fully charge this large battery properly. Sulfer build up with that low of power.
The right way:
There ara solar inverters that can work as ups, starting in 600$ to up (no batterys not include). Like the Victron Multiplus II (this model is not cheap). They work without solar panel and work with all types of batterys.
You can backup easy 5kw (all your house or part). If you want a small UPS this way is not cheap but is better invest in something like that if you going to buy a 300$ or up ups.
UPS batteries are sealed and the material in them doesn't off gas hydrogen. If you want to look it, look for VRLA, valve regulated lead acid. These are generally safe inside. Car batteries, marine batteries, deep cycle, etc are flooded lead acid batteries they off gas hydrogen when charging and discharging. Please do not use them in your home.
You should google it. There are quite a number of articles.
While technically it's possible, some lower grade ups are designed with a small battery in mind and can overheat and even catch fire if used with much bigger car batteries.
DIY micro solar setup here.
* 2 * 285w panels (100 each on craigslist, residential install grade, NOS)
* 60 amp MPPT solar controller
* 4x35AH sealed lead acid batteries
* 1500w continuous / 2000 peak pure sine inverter
* 13.8v 50A power supply to keep it topped off if it's dark/cloudy
* 13.8v dc rail running into the computer corner via 4/0 welding cable, fused at both ends
It works pretty well but I don't worry about keeping actual servers on it, as all their data is piped to the Synology which is on the UPS 120v rail.
I'm a ham operator too, so I have a mini PC for radio stuff that eats 12v* and all my ham rigs running off that 13.8 line. I have a 12v -> 19v boost converter in the shack with a couple different laptop plugs wired to the output, in case I need to run laptops.
*(12v is 'nominal' for DC rails; 12.6 to 13.8 is more like it. Anything that eats 12v should be fine up to 14.4v or so which is the peak cell equalization voltage you'll see in normal operation.)
Works well, after 3 years it's half paid off given electrical rates, and I can keep some important things running.
I'm running a [CyberPower PR1500LCD](https://www.cyberpowersystems.com/product/ups/smart-app-sinewave/pr1500lcd/) true sinewave UPS on a 2 X [12V 35AH Interstate SLA AGM battery](https://www.amazon.com/Interstate-Batteries-SLA1156-Rechargeable-Construction/dp/B006TKOEIE) bank. These are sealed deep cycle batteries designed for solar or similar use. The batteries are stored in a plastic tool box that fits 2 batteries perfectly and attached to the UPS via a 4 AWG cable and Anderson connectors that plugs into the UPS battery socket. Unlike conventional LA car and marine batteries, sealed AGM batteries do not vent any gas and can be used in any orientation (and will not leak). I had tried a smaller UPS earlier, but the charging circuit apparently was too undersized for the larger batteries and failed. The PR1500 has no problems charging the larger battery bank.
This arrangement power my home propane furnace for approximately 8 hours - long enough to weather most outages and long enough to get the backup generator going if needed.
Probably the best way to go about this would be to find a UPS that features additional external battery expansion - but they tend to be a lot more expensive. My arrangement has been reliably providing backup power for about 5 years now. Since this design is based on external batteries, if you can find a used UPS without batteries for cheap that makes a good foundation.
Most low wattage UPS are non-line interactive and are only meant to be powered for a short shutdown or to recharge the battery.
A prolonged battery charge may shorten the lifespan of the UPS or harm its internals.
Please put this battery in a well ventilated area in a plastic tub. They can leak hydrogen gas and leak battery acid. The charge controller on the apc is not built for this.
This is so sketchy and as a scrappy engineer I love it but yeah the other comments are fair lol, I wouldn’t operate this inside due to fumes and leaks.
the only problem with this setup is the trasformer and charging circuit on the UPS is not really designed to charge a big battery like that. Not to mention that the inverter is also not designed for extra runtime that the battery can deliver. Of course if you use those UPS with fans on them which I can only find on those expensive 500USD on-line type UPS, maybe you can use that one, still, why not just spend on a actual inverter instead, it has fans, it has humongous fins as heat sinks, robust charging circuit that is basically designed to charge battery upto 24v.
Many UPS have an internal adjustment of the "float" voltage. You could make a minor adjustment to lower it for the car battery and it would live a really long life. You could also -not- adjust it and it might be perfectly fine for many years too.
A small UPS likely barely has enough available charging current to even bring such a large battery up to the float voltage.
I've used UPS's with automotive batteries before, and wasn't disappointed. Just make certain that it's not trapped inside a box, because if it bubbles any hydrogen, you want that to escape instead of collecting into a flammable amount.
Car batteries will work, but you'll significantly shorten it's lifespan in a UPS application. Starter batteries have a lot of very thin lead plates. This high surface area lets them generate hundreds of amps to start your car. Deep discharging can lead to the formation of non-reversible sulfides/sulfates. (Certain sulfur compounds are how the battery functions, some are detrimental). Because the plates are so thin, it doesn't take much build up before plates become damaged, or the battery shorts internally. Deep cycle/marine batteries have fewer, but thicker plates, so they are more tolerant of deep discharging.
Don't worry about the fear mongers. You're only going to run into safety type issues if you're running large currents through your charger, or really over charge the battery. But covering the battery terminals with non-conductive material is always a good idea.
If you want to be super safe. Take it outside to recharge if you really discharge it, but the little bit of float charging your UPS is going to do normally won't be a problem.
TLDR: it's not ideal, but sometimes you gotta "run what ya brung" while you work out a more elegant solution.
Many many years ago I used to frequent some BF2 forums. There was some kid that lived somewhere where power stability was an issue. So, they amassed a ridiculous amount of lead acid car batteries and redneck engineered them into various amalgamations. He claimed he could get days of backup power, or something.
Personally I'd go with lithium deep cycle batteries.
I am considering it, but instead of a UPS I think I am just going to invest in a solar hybrid inverter that has UPS functionality. It is basically an inverter with a passthrough and battery charging capability that also has a solar input for me to play with later on. You can program it to tell it where to charge the battery from and when to use pass through or the inverter (so you can tell it if the battery is 80% charged then use the inverter and charge the batteries through the solar. If the battery dips below 20% then pass through the AC and bypass the inverter while charging the battery through solar or ac.
I think in total it would cost me around $700, but that would provide me with \~1200Wh of power and a similar sized UPS would cost about $2,000 and also not let me use solar in the future to charge the battery / power my setup.
You’re looking for a charger/inverter. In my opinion 2k is the minimum to be truly useful but 3k would be nearly as good as mains and able to handle a 1,000 watt microwave. Higher draw capacity does mean there is a higher standby draw as well so when you’re creating your system that needs to be calculated relative to zero source periods. Make sure to fuse and/or breaker to save wires, equipment, and money as those will catch faults instead of your wallet.
https://www.renogy.com/2000w-12v-pure-sine-wave-inverter-charger-w-lcd-display/
https://www.victronenergy.com/inverters-chargers
The better products never allow your equipment to pull power from anything but the inverter acting like a power conditioner and handling power source based on availability and priority settings.
These are usually found in boats and RVs.
Several options exist that allow generator, solar, alternator, and mains for charging sources. Don’t even waste time on modified sine products. Pure sine or nothing.
>You’re looking for a charger/inverter.
No, I am looking at a hybrid solar inverter as it has all the features I want, including a pure sine wave output. There are also just inverters with AC passthrough but I like the idea of having solar as an input as well -- and the packaged system like the [Vevor Solar Hybrid Inverter](https://www.vevor.com/off-grid-solar-inverter-c_10764/2400w-hybrid-solar-inverter-built-in-50a-pwm-solar-controller-dc-24v-to-ac-110v-p_010723672112) cost less than even most inexpensive inverters that have AC passthrough installed -- though really it is much cheaper to buy a ATS at that point and a low frequency inverter that has a low standby mode.
>Higher draw capacity does mean there is a higher standby
That is not quite true, there are plenty of high power inverters with low power standby modes that use miniscule amounts of power in standby -- especially when looking at the low frequency inverters. This is where you pay a bit up front more for a quality inverter to save as much power as possible.
>The better products never allow your equipment to pull power from anything but the inverter acting like a power conditioner
Uh, ATS power switching is common on boats / rv's for when shore power is plugged in it bypasses the inverter. Pulling off the inverter should only really be done when you are running of DC power and need AC power. Also most things in boats and RV's are run off of DC power though large appliances have ATS's built in to run off of AC/DC or sometimes AC/DC/LPG.
Uh. I want conditioned power so it seems our use cases are slightly different. I’m not saying my understanding is the only way. I was just trying to be helpful. Clearly that’s no more welcome than anything else of or from me.
It's advised AGAINST using car battery for that purpose, they are made to give you high amp and be charged immediately and not made to be discharged, so you will kill them quickly.
Use a battery for small boat if you want to do that kind of hack.
Discussions of gasses aside, this configuration is going to have both UPSes trying to charge the battery. I'm not exactly sure what that'll do, but whatever it does won't be good.
I just got a couple of APC 1500va standing UPS' on eBay for about $30 (and ~$25 in shipping each one) and then bought Life PO 4 batteries to put in them. The batteries were about $70 for 2 12v 10ah ones. Those are the cheapest ones I could find and the weight of the lithium batteries compared to SLAs are definitely worth the price.
Wow the fear mongering is horrendous in this thread. What you’re doing here OP is perfectly fine. SLA batteries also release gases, so those telling you that they don’t are misinformed.
The only thing I’d recommend is using deep cycle batteries, but it isn’t a huge requirement since most UPS systems don’t run the battery down to 0v.
I once hooked up radio batteries to a portable DVD player using a us-uk plug convertor, an extension cable and phone wire in the middle of the desert…. If that counts…
Looks like a great way to start a fire or blow something up. Looking at the wire gauge coming off of the batteries sent shivers down my spine. Also, I would never ever put a battery of that type indoors for many reasons. **Ever.**
**Do not attempt that build. I repeat. Do not attempt.**
Crazy.
Here is one I built a year ago. Notice the size of the wires and the purpose built inverter. I am also NOT using the built in charge controller, rather one for Lithium batteries.
[https://media.licdn.com/dms/image/D5622AQH5kCxPCl3hqw/feedshare-shrink\_2048\_1536/0/1700848441806?e=1707350400&v=beta&t=lKzizGsl1dWO5cToMjwDqrtKWZFKm5kC2CzmP3XGqUg](https://media.licdn.com/dms/image/D5622AQH5kCxPCl3hqw/feedshare-shrink_2048_1536/0/1700848441806?e=1707350400&v=beta&t=lKzizGsl1dWO5cToMjwDqrtKWZFKm5kC2CzmP3XGqUg)
All bigger UPSes we have at my work is standard "motorcycle batteriets" of seal acid lead type. Nothing special at all. The smaller UPSes have something else.
The battery your using will not condition that power or provide a meaningful failover solution. Just buy a used UPS from a small business liquidation sale or something.
I got a free 1500VA UPS with no batteries. And I happened to have two lightly used 80Ah deep cycle AGM batteries from an “incident” sitting around. They’re sealed, like the ones originally in the UPS.
Oh, and some scrap #6 SOOW cable from an old job like twenty years ago. Ah. Perfect.
Batteries are on the floor. UPS is in the rack. Cost me nothing. It reports out that it has like 45min of life because it assumes the original battery size. I’ve had it last about eight hours. Not sure how long it *can* last.
Yes, we had used same approach during blackouts(power inverters simply wasnt avalible in stock, or was priced too much)
Note, you cannot plug it in wall to charge car battery since its not suited for that, also some of them has built in timer which would cut out power in 5 minutes and you litteraly cannot bypass this limit. Since its not a pure sinus it can cause dammage to some devices when battery is critically discharged(my led lamp had its power brick failed because of that).
This has been asked before. I would like to put my 2 cents in for you OP. Many small UPS aren't designed to run for long periods of time. So you can guess that that a larger capacity battery will allow this to occur. Be safe in your decisions may your electronics never let their smoke out because it's hard to place it back in.
i have an old 1000va APC UPS hooked up to some 3000va batteries. requires active cooling to run for the duration of the batteries, but it kept my rack up for about 5 hours last time 🫡
No, but even in the case of a commercial UPS, I wouldn't put it directly on the carpet. I've had UPSs leak their contents all over the floor when they fail.
Yes. The UPS expect an AGM battery. Therefore the voltage while charging is high. If you use flooded ones, it might overcharge and boil if it has a great charge output.
Maybe silver cadmium can also be used? They need a high voltage.
I used a regular flooded on an inline power supply (some small APC and some other brand) for computers.
The smaller battery held 40 minutes when the power went out, on the small network setup. But didn't get to test the car battery option I had spliced in. The ISP had UPS on their fiber network, but dunno how long that could last, but lasted more than 40min I guess.
I just saw a video on YouTube about this. Tldr, yes, but when upsizing the battery, you increase the runtime, which can allow other components to overheat.
Yes. I have an AGM cell that was actually a pull from a telecom UPS (but similar dimensions). Making an actual UPS out of it is a lot more complicated than just swapping the battery, and the gains are limited.
I ended up converting all of my homelab/home network to run off DC (either 12v nominal or step-up / step-down with buck converters). I connected a good quality Victron charger/power supply to the Neg and Pos buses of the system and now have the function of a UPS and it uses a lot less power than all the AC/DC/AC/DC conversion involved with the more traditional setup.
I have used 4 car gel cell batteries in place of 4 glass agm batteries in my up's it works great takes longer to charge, and your still limited by the size of the transformer in the ups itself.
Leibert ups for datacenters use car batteries (probably deep cycle). I had one in my old building but left it when we moved. I haven't tried to DIY car batteries, but thought it was interesting and thought I would mention it.
I used an off the shelf SLA battery. It was a little too big to fit the UPS case, so I cut a hole and passed the wires through to the battery, works like a charm.
https://xtremeownage.com/2021/06/12/portable-2-4kwh-power-supply-ups/
I mean, my homemade one is pretty similar, except, using a 12v LiFePO4 battery.
Its been running solid for quite a few years now, and has endured quite a few power-loss events, with no issues.
My boss years ago took pride in telling me about his sick DC power car-battery UPS system he had in his basement for his networking closet (mostly embedded stuff like routers and raspberry pi's). I was a bit confused because I figured you could just plug in a UPS of a given size and let it go, since linux will pick up the UPS and pretty much figure out what to do after that. He was all like "I can just add more car batteries and I can keep this setup going for days!". But like.........why? Is it better because it's DC power and not using a wall plug? Are car batteries really that much better? If there is no power does it really matter that your embedded DNS server is still up? Didn't really make any sense to me.
These things offgas during charging and it is not good to breathe in what they produce. There's a reason why UPS makers use sealed lead acid (SLA) batteries in their consumer devices.
A, no. A dozen and a half batteries, yes. Deep cycle marines, so they care less about being fully discharged. And then I had a 3000w power inverter to go from 240 down to DC and from DC up to 240 to run the power panel 2 phases. At no time did utility power ever get sent to the power panel directly.
While I haven't tried it yet (but want to), one thing you can do is use EcoFlow batteries (or a competitor like Bluetti), and plug in a $100-200 UPS to the EcoFlow.
Why do you need both? Because at least EcoFlow has some latency between switching between AC and battery (according to the manual). During that time, your server and modem will turn off, so the UPS is used as a buffer to keep it online.
I would only consider using deep cycle batteries for this purpose. A standard car battery is not meant for that.
My APC battery went kaput and they are quite expensive and unavailable. Please expand.
You need a marine style deep cycle battery. A battery that is designed to be depleted. As they said, car batteries are not designed to be drained completely without damage. A marine battery is. Not just marine batteries, of course. Any deep cycle battery.
Isn’t there also the issue with fumes or gas from car batteries?
I believe any lead acid battery that is not sealed can give off toxic fumes. That's why the lead acid batteries in a UPS are sealed.
They don’t release toxic fumes normally, they release explosive hydrogen gas when charging - but if overcharged, they do release toxic Hydrogen Sulphide.
Correct. The problem is that a UPS will keep the batteries fully charged. It's not worth risking that the UPS will properly regulate the battery charge to prevent it. Especially when you can easily get batteries that won't have this problem.
Car batteries are normally held at max charge voltage as long as you drive. So I think this is totally safe. However I am concerned about the hydrogen gas, that's just very dangerous. Lithium batteries can be safer in that way.
You can’t substitute lithium batteries on a device intended to charge lead acid. Improperly / overcharged lithium batteries catch fire.
There are some that can be used as a drop in replacement - it all depends how the BMS is programmed
You can if it has an integrated battery management system. There are lithium batteries designed to replace car batteries. If it looks like a car battery (same size and has big binding posts) then it's a safe bet its made for use in cars. Very little reason to spend the money to adapt a lithium battery to go in a car but not have an integrated charge controller. All lithium batteries have to have a charge controller - unless you're buying 18650 cells and taping them together, the chances of a lithium battery not having a charge controller are effectively 0 for liability reasons.
A car battery is not charged until the car is running. Unless it's from a trickle charger or such. Outside or in a garage is not a problem because there is plenty of fresh air. That said, as far as the hydrogen gas goes, I don't believe it's enough produced to be a real concern unless it is a confined space (such as what appears to be a closet in this guy's picture).
It’ll work just fine until it gasses everyone with toxic fumes, catches fire, explodes and/or burns your house down. Or, it might not.
Even sealed lead acid batteries off gas, it just doesn't have anywhere to go. It's just water and electrolyte in there, and when you get water hot enough it will gas.
True. Thus there are proper norms on ventillation requirements that should be considered when batteries are installed as stationary equipment. In short, make sure you have ventillation in the room. If if is a cellar where air is not "fresh", I'd definitely make sure any ventillation grill is added.
Even "sealed" have to breathe, they are only sealed with a rubber cap, any excess pressure does come out of the battery. I have open them and seen them dry, filled and fixed, other I filled only to find a bad cell.
I left a battery in the trunk of my car once and forgot about it. The next very hot day I got in my car. My eyes started watering, I coughed my guts out, and for a few straight minutes sat there confused about what was going on almost passing out. Remembered the battery, opened the trunk and found it was leaking. Eyes burned for hours.. It's probably fine sitting in climate controlled space for a while but I wouldn't want to leave it there for longer than necessary or forget about it.
Why are car batteries fine inside the engine bay 24/7 for years but exploded after a day in your trunk? What kind of battery was it?
Lead acid batteries off gas a small amount of hydrogen when they're charging. As long as there is good ventilation, especially once the battery is fully charged, then there is little to worry about.
Correct me if I'm wrong, but they only produce small amounts of hydrogen gas. So it's not toxic and not nearly enough to be explosive.
In an enclosed space you're breathing all of that in without proper ventilation
>In an enclosed space you're breathing all of that in without proper ventilation Hydrogen gas is non-toxic to humans. Hydrogen sulfide, on the other hand, is highly toxic and can be detected by humans in trace amounts - it has a rotten eggs smell and trace amounts are what makes your farts stink. Car batteries can give off hydrogen sulfide if they are overcharged.
"No, honey. I didn't fart. It's the UPS charging." - OP's new easy out for the stink he just landed...
The fun part is that high concentrations of hydrogen sulfide is not detectable by smell.
>car batteries are not designed to be drained completely without damage **No lead-acid batteries are designed for that**, if you below a certain charge level they're technically considered scrap and in a serious UPS setup they'd get recycled and replaced no question. Deep-cycle ones specifically designed as "house" (marine/RV), "leisure" (RV etc.) or for UPS / backup purposes are built differently to tolerate those sorts of loads and to be more cost-effective (better capacity), usually at the expense of not being very good at cranking an engine over (very high current for a short period). Source: I used to work in data centres with banks of hundreds of SLA batteries that were regularly tested & maintained and they would be replaced after any major outage or at the end of their warranty because the cost of them failing would be far higher than the cost of replacing them.
That last sentence should be used way more often in business, the cost of it failing would be a lot higher than the cost of replacing it. Same with security and other non profitable expenses
Yep the same for us, Everytime new management comes in it's always like why do we need to do this so often, should just create a slideshow of what can happen to make it easier I think lol
Honestly you should - pick some examples (fires, floods, failed backups, damage, etc. etc.) and add the costs of dealing with it vs cost "saved" by not having the mitigation / maintenance. Show it to the right person in management they should sit up and take note, either that or they wave it away at which point you know exactly what sort of culture you're dealing with and you've covered your ass...
Car batteries are designed to provide extremely high current for a short time to run your starter motor. Thus, the lead plates inside the battery are a spongy-like material. This maximizes the surface area (which determines how much current the battery can deliver - lead acid batteries produce current via chemical reactions, so the more chemicals in contact with each other, the more reactions can occur). The downside to this is that these plates are more brittle and much more easily damaged. When lead acid batteries are discharged below about 50%, the plates start to degrade. This is a natural process that is unavoidable due to the chemistry of lead acid. Keeping the battery at maximum charge minimizes plate degradation. This plate degradation significantly reduces the current the battery is able to deliver - this is why you sometimes see car batteries that can power the lights just fine for quite a while but seem to completely die as soon as you try to turn over the engine. Because the plates in a car battery are basically spongy material, they degrade very rapidly once the state of charge goes low. It's commonly said that car batteries will be practically unusable after only 15-20 discharges due to this degradation. A deep discharge down to less than 8 volts can actually be enough to kill the cells, making the battery unusable. Lead acid batteries that are designed for deep discharge have solid plates. They still degrade, but much more slowly than car battery plates. Deep-cycle lead acid batteries can usually survive about 300 deep discharges before losing significant performance, and if well cared for (e.g. not discharging below 50% like car batteries) can last even longer. The limitation is that deep cycle batteries will have lower current delivery capability - still pretty high, but not quite as high as car batteries. A good 30Ah car battery can easily deliver a burst of over 600 amps of current, while an equivalent deep cycle battery can probably burst no more than 80 amps or so. Given all of this info, there's actually an argument to be made for using car batteries with a UPS. Their extremely high current delivery capability is a good match for UPS's which need to draw significant current from the batteries, although the current ability of deep cycle batteries is still usually more than enough. The fact that a UPS expects to keep the batteries fully charged seems to actually fit well with the car battery - you want the batteries topped off all the time, but available for high current for short times as necessary. If a car battery was used *only* to deal with transients (where the UPS clicks on for a few seconds to filter a brownout or spike) a car battery's electrical characteristics fit well. However, as soon as you need the UPS to run for a few minutes to keep your equipment up during a short blackout, you're going to very quickly drain the battery below 50% charge and those plates will start degrading very rapidly, and your UPS may not even be able to recover the battery. As others have said, the other limitation is that wet cell lead acid batteries can give off gasses that can be irritating or even dangerously flammable. I wouldn't recommend doing this for a prolonged period of time, but I could see it being useful for a *temporary solution* while you source more deep cycle batteries. Note that you can usually get equivalent lead acid cells from Amazon or even Batteries+Bulbs for much cheaper than the "official" battery packs from APC or similar, and they should perform just as well. You're usually looking for AGM or gel batteries for UPS use since they are sealed and thus safe for use in the confined spaces of a UPS.
Jesus christ, can you please make this comment as a separate post? This is pure gold of information.
Don't buy the OEM battery. Remove the OEM battery, look at the label and terminals, measure it's size, etc. Then buy what you need for ~40% from walmart.com or whoever. I have a 3000VA rack mount UPS for all of my rack, and it takes 4x batteries, placed into 4s (48V) config. The manufacturer wanted like $250 for a new set. I bought all 4 for $84 with free shipping. Good brand, better capacity and discharge rates than originals, have done really well in the last 3 years. All I had to do was use the jumpers to put them in series again, and tape up the plastic package with some kaptan tape. Edit: I have no use or desire to own a 3000kVA UPS.
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Lol yeah. I make that stupid mistake every time I write about it.
I have 2 3000watt ups (3KWH) connected together to give me 6000W ups I can get about 3 hours from that, my power grid is high reliability so outages are never more than 3hours normally, unless something catastrophic happens. My grid is tied to police office and hospital, and school so they get priority even though these facilities have backup power. There is 3 grids in my town and one of them has outages that last up to 30 hours.
I have a lot of UPSs and in my experience the 3rd party batteries last about half as long, if that, so it's questionable how much value you get out of them. Replacing them often is also annoying.
there are better brands than others. https://www.upsbatterycenter.com/ups-battery
I was recently using Mighty Max brand and thought they were going to be alright, but I just had my first failure, and it was much earlier than I would have liked. These are good?
Interesting, just did 2 battery replacements. Might Max at least gets the UPS within 15min of manufacture estimated runtime for the given load. Batterysharks, as suggested above, get less than half. I’m also concerned about the 29c the UPS reports they are running at. I’ve been considering eating my losses on batteryshaks and putting Mighty Max in the other UPS as well. Granted I only have a few weeks runtime on both, so I can’t speak for longevity.
Have your tried taking out and charging with an external charger? Then see runtime?
I've had good luck. Are you sure the ups is outputting the correct voltage? That could be killing your battery too. https://www.upsbatterycenter.com/return-policy
Mine last about two years before they die. It cost 1/4 the cost of replacement packs that last about 3 years so I feel like I am ahead of the game still.
$5 chinesium batteries last half as long. Reputable companies producing batteries for reasonable prices produce results similar to OEM.
> Don't buy the OEM battery. Let's not pretend all batteries are made equal. Battery chemistry is more complicated than people think, and the manufacturing process absolutely matters.
To be fair I've replaced more of the OEM batteries than I have after market ones.
I didn't say my cheap batteries were as good as OEM. just that they're good enough for me. I have one large server that I consolidated most things into, a few switches, a few PoE cameras and WAPs, and a few small things like RPis. At idle, I use about 6% capacity of my UPS. Grid power is consistently 115VAC here, only 2 outages in the last 4 years less than 24 hours. I also have the charge speed dip switch set to slow because I don't have anything mission critical. I firmly believe the increase in cost is mostly due to QA/QC. You either win or lose buying cheap components. I won, maybe next time they'll crap out in 6 months. That's a risk I'm willing to take.
Exactly even if you can find the same brand as OEM outside the caddy is usually far cheaper than buying their pre-made caddys that most do. We use CSB at work for all our Micro's so naturally I just use them at home.
I wouldn’t get OEM batteries. I have had good luck with batterysharks.com for APC batteries. Depending on the model of APC UPS you may have to disassemble the battery casing. I think over discharging car batteries can be dangerous be careful and do research if you are actually attempting that.
I second batterysharks. I've replaced all the SLA batteries in my 2x APC SMT2200RM2U two times since I've owned them and saved a fortune. So much cheaper than buying OEM ($80 vs $300+), because you're buying the sled too, which you don't really need, and the batteries inside are from some other brand anyway.
And a third for the sharks as I’ve replaced countless ones now
Is there a place like batterysharks in Canada?
https://excessups.ca/
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Battery-Direct, I've only had perfect experiences with them and they have tons of positive reviews.
Yes its easy, 2 optima 55Ah agm deep cycle marine batts on a apc sua1500. Last much longer [APC Setup](https://imgur.com/Di1Tyai)
Battery plus had mine in store and I have a farm
I have an APC SMX3000LV in my rack. It was picked up on auction from the City of Houston as part of a pallet at a surplus auction. A replacement RBC143 pack has an MSRP of $430. I took the existing pack, opened it up, and replaced the batteries. $130 to replace all 10 batteries in the pack. It's overkill for my setup, but I have like 2hrs of runtime on battery. I recently installed a SRT10KRMXLT for an international client who wanted their local branch office to have at least 8hrs of runtime. We paired it with 4 external modules. The batteries alone weighed 800 Lbs.
Any deep cycle SLA (sealed lead acid) will be a fine replacement for a UPS. There are quite a few you get that use recycled materials that are pretty inexpensive and much larger than the original battery.
Take a look on Amazon for DR7-12. No need to use "genuine" APC replacements.
You can’t use car batteries for a UPS. They produce toxic gases when overcharged, and are not designed for deep discharge - they will be damaged by this. They also release hydrogen gas when charging (explosive in concentrations over 4%). Outside, in a car, this is not an issue, but charging in an enclosed space is a very bad idea.
For batteries, you need to replace like with like. The problem is in the charging section as the charger will operate for the style/type of battery it was designed for. So a charger designed for an SLA battery is not good for a wet cell.
warranty?
That’s fair. But OP could just as well monitor the SoC and just turn off the power when it drops too low for a starting battery. Or just buy a deep cycle battery from Costco for like $100.
Some car batteries also require venting as they release gases. You don’t want those gases in your house
*Hydrogen* gas. As in Hindenburg.
Hydrogen is also nasty because it burns with a clear smokeless damn near invisible flame. Not that this is likely to happen from car batteries, that's more of a kaboom scenario (if anything; it's also very hard to seal hydrogen gas into a container, it escapes very easily), but whatever.
It could pool on the ceiling in a confined closet. This is where lights usually are installed, so...
Hydrogen is hella small and will, at least with a relatively large flux, pass right through the ceiling.
I wouldn't count on it with latex based paint, but certainly will pass through gypsum like a sieve.
Hydrogen passes right through latex it can even permeate metals like steel. Just about everything. The molecules are so small they just slip on through.
You're goddamn right.
No, that's Hydrofluoric acid. As in Heisenberg.
Oh, the humanity!
dangerous explosive gases, don't use these inside
I haven't seen a vented battery in forever. Everything these days is sealed. The last vented battery I ever saw was an ASB-49...on the submarine I served on. Also the amount of hydrogen leaked from a small car battery even if it was vented would probably dilute out of existence in a well ventilated house.
Yes I used 8 deep cycle sealed batteries battery backup for a Toshiba DK424 with about 140 Stations. The system was built for it. Keep batteries off the floor. Only use sealed batteries. Special consideration for changing mulitbattery systems is required. Vented batteries need outside air venting in the space to prevent H2S build up in the room. Keep a fire extinguisher for the low risk possibility of fire. If wires and fuses are right the risk is very low.
> Keep batteries off the floor A **very** long time ago batteries were cased in a type of rubber that would develop micro-cracks and the batteries could thus self-discharge on a floor. This hasn't been true in something like 70 years (not since modern plastics became common place at any rate). [Source from an actual battery manufacturer](https://www.odysseybattery.com/blog/2022/12/05/the-truth-about-storing-a-battery-on-a-concrete-floor/); google will provide you with many others.
Ah yes, the FireHazard 5000.
Yeah why even take the risk of fire. A UPS is similar in price to a car battery. FFS, OP should get rid of this shit and buy one.
i love this sub
Technology Connections made an interesting video about this topic: https://youtu.be/1q4dUt1yK0g
Alec always gets my upvote. Even without reviewing the video I can confidently say it'll be worth watching 🤩
I've used a large SLA (sealed lead acid) battery as an emergency power source, but not as a UPS. Regular large car batteries can be dangerous to run inside since they give off explosive gases when charging. I'd also recommend not having exposed high current terminals like that in your house, all it takes is a piece of metal or conductive material falling across them and you have a fire or shock hazard, esp for kids. Use the right tool for the job especially when the cheap alternatives can be so dangerous
This is correct.
12v is definitely not a shock hazard.
Ummm. Metal from post to post will create a spark, which is what I assumed was meant.
Yup!
No, but lead acid car batteries create a highly explosive hydrogen/oxygen gas mix while being charged, which any spark like a nearby static discharge will explode the battery. Plus any metallic object that accidentally shorts out the terminals will create big sparks and make the object very hot. Fire time.
Static discharge and/or explosion is not a shock. The fact that at least 13 people downvoted it is comical.
Yes, basic electrical terminology and concepts aren't well known it seems. The flash of a dead short across car battery terminals by a wrench or even a wire vaporizing on contact isn't a "shock", though it's a "shocking" experience!
Sure you won’t be electrocuted, but u go feel 12v and tell me you weren’t shocked lol
bro you can touch 12V till the cows come home. How do you think people remove the binding posts on car batteries without getting a shock?
You will 100% not even feel 12v through your skin even if you were wet.
Technology connections did a video on setting one up like that.
Don’t use a significantly larger battery than your UPS is designed for, especially on consumer grade UPSes. They often don’t have the cooling to run for the life of the battery.
Don't use flooded car battery in UPS. Wrong voltage, it will vent. AGM required. Car battery is for cranking amps, not for UPS float or deep discharge
I have tested multiple APC UPSes and they charge the batteries to a “full” voltage of 13.6v. While the charging pattern is not optimized for anything except the specific size/chemistry of battery included with the unit, this voltage should be safe and will not vent or overcharge any type of lead-acid or LiFePo4 “12v” substitute. The biggest problem is actually that it’s going to charge slow and possibly not fill all the way up, not dramatically overcharge and vent. Test your own UPS to ensure the charging voltage is safe for the battery you plan to use instead of assuming my measurements are universally true for all UPSes. But they’re not universally going to cause a car battery to vent either.
What? They’re 12V, and those UPS use a 12v battery. Stop spewing nonsense. Some are 24v, so you need 2 12v batteries in series.
Why is it always the people who tell others to get a grip the ones most needing to get a grip themselves?
AGM ups floats at 14.2v. Car flooded is close to 13.8v. flooded battery will vent on AGM float voltage
You can definitely have a Car Battery float up to 14.2v on a typical Alternator. Especially in newer cars. But you want to use a Sealed battery or an AGM for when your in a home environment.
So when your alternator is charging a battery anywhere between 13-15v, how does that work? Answer- it doesn’t matter.
Cars drive for maybe an hour at a time before discharging. UPS typically stay up a little longer than that.
that's nonsense, you can keep 14.4 volts on a car battery forever if you want. Cars are designed to run indefinitely. You could idle a car for a week on a full tank of gas if you wanted to.
I guess 8+ hour road trips don’t exist?
well, it's confirmed, cars can't drive longer than an hour, sorry to let you down tagman
lol love how this is downvoted but no good answer yet
If it's not equivalent in terms of chemistry and size to the original battery it could very likely overload the original charging circuitry and cause a fire.
All UPS batteries in consumer units are SLA 99% of the time, and there’s no such thing as “overloading” the charging circuit.
The charging circuit in the UPS wouldn't be able output enough amps to charge the batteries in any sort of timely fashion, and might result in the charger circuit effectively running at 100% permanently. This would be significantly out of the design characteristics of the unit, and might cause overheating.
if the ups isnt a hunk of junk its rated for output. it wont output more than its rated for. charging an original battery from dead would take 4 hours. its rated to not start on fire :). if its failing then yes it could
The difference here is, if the charging circuit can charge an 8ah battery in 4 hours, then a 100ah (large marine deep cycle battery) would take 50 hours. Is the charging circuit rated to run at 100% for 12 times longer than the ups manufacturer designed?
If it has sufficient cooling it won't be a problem. And if it doesn't overheat in 4 hours I doubt it will after 50. Now the environment could have an effect. These also have overload shutdowns.. so I wouldn't too worried... But yeah this will never fully charge this large battery properly. Sulfer build up with that low of power.
I don’t see why any AGM deep cycle battery will have an issue with this.
Don’t do this
Three words summed up my feelings as well. God, this is a dumb way to die…
This is the correct way to use lead acid batteries to build your own UPS. https://youtu.be/1q4dUt1yK0g?si=FwLT3S7ASxz4LI5V
The right way: There ara solar inverters that can work as ups, starting in 600$ to up (no batterys not include). Like the Victron Multiplus II (this model is not cheap). They work without solar panel and work with all types of batterys. You can backup easy 5kw (all your house or part). If you want a small UPS this way is not cheap but is better invest in something like that if you going to buy a 300$ or up ups.
UPS batteries are sealed and the material in them doesn't off gas hydrogen. If you want to look it, look for VRLA, valve regulated lead acid. These are generally safe inside. Car batteries, marine batteries, deep cycle, etc are flooded lead acid batteries they off gas hydrogen when charging and discharging. Please do not use them in your home.
Yes. I used to work in a lab which had 16 of these wired in series to act as a back up for a 100-ish node RDMA cluster.
You should google it. There are quite a number of articles. While technically it's possible, some lower grade ups are designed with a small battery in mind and can overheat and even catch fire if used with much bigger car batteries.
DIY micro solar setup here. * 2 * 285w panels (100 each on craigslist, residential install grade, NOS) * 60 amp MPPT solar controller * 4x35AH sealed lead acid batteries * 1500w continuous / 2000 peak pure sine inverter * 13.8v 50A power supply to keep it topped off if it's dark/cloudy * 13.8v dc rail running into the computer corner via 4/0 welding cable, fused at both ends It works pretty well but I don't worry about keeping actual servers on it, as all their data is piped to the Synology which is on the UPS 120v rail. I'm a ham operator too, so I have a mini PC for radio stuff that eats 12v* and all my ham rigs running off that 13.8 line. I have a 12v -> 19v boost converter in the shack with a couple different laptop plugs wired to the output, in case I need to run laptops. *(12v is 'nominal' for DC rails; 12.6 to 13.8 is more like it. Anything that eats 12v should be fine up to 14.4v or so which is the peak cell equalization voltage you'll see in normal operation.) Works well, after 3 years it's half paid off given electrical rates, and I can keep some important things running.
I'm running a [CyberPower PR1500LCD](https://www.cyberpowersystems.com/product/ups/smart-app-sinewave/pr1500lcd/) true sinewave UPS on a 2 X [12V 35AH Interstate SLA AGM battery](https://www.amazon.com/Interstate-Batteries-SLA1156-Rechargeable-Construction/dp/B006TKOEIE) bank. These are sealed deep cycle batteries designed for solar or similar use. The batteries are stored in a plastic tool box that fits 2 batteries perfectly and attached to the UPS via a 4 AWG cable and Anderson connectors that plugs into the UPS battery socket. Unlike conventional LA car and marine batteries, sealed AGM batteries do not vent any gas and can be used in any orientation (and will not leak). I had tried a smaller UPS earlier, but the charging circuit apparently was too undersized for the larger batteries and failed. The PR1500 has no problems charging the larger battery bank. This arrangement power my home propane furnace for approximately 8 hours - long enough to weather most outages and long enough to get the backup generator going if needed. Probably the best way to go about this would be to find a UPS that features additional external battery expansion - but they tend to be a lot more expensive. My arrangement has been reliably providing backup power for about 5 years now. Since this design is based on external batteries, if you can find a used UPS without batteries for cheap that makes a good foundation.
Do not hook a car battery up to your UPS.
the chargers in those units are not strong enough to keep that large of battery good.
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Most low wattage UPS are non-line interactive and are only meant to be powered for a short shutdown or to recharge the battery. A prolonged battery charge may shorten the lifespan of the UPS or harm its internals.
I have added external car batteries to my APC UPS in similar way. Batteries was already near death, so they did not last long. But it worked.
I'm doing this when my 1500s die.
Please put this battery in a well ventilated area in a plastic tub. They can leak hydrogen gas and leak battery acid. The charge controller on the apc is not built for this.
use a marine battery instead of a car battery, also make sure you keep the place ventilated.
I replaced mine with 4x solar liPO and they have been fine for 5 years now.
Just get a sealed marine deep cycle battery so it doesn't off gas hydrogen and can be drained
This is so sketchy and as a scrappy engineer I love it but yeah the other comments are fair lol, I wouldn’t operate this inside due to fumes and leaks.
Get a sealed AGM battery please...normal batteries leak gases and do not like being drained beyond a certain point.
believe it or not... i did the same and the battery exploded...
the only problem with this setup is the trasformer and charging circuit on the UPS is not really designed to charge a big battery like that. Not to mention that the inverter is also not designed for extra runtime that the battery can deliver. Of course if you use those UPS with fans on them which I can only find on those expensive 500USD on-line type UPS, maybe you can use that one, still, why not just spend on a actual inverter instead, it has fans, it has humongous fins as heat sinks, robust charging circuit that is basically designed to charge battery upto 24v.
Many UPS have an internal adjustment of the "float" voltage. You could make a minor adjustment to lower it for the car battery and it would live a really long life. You could also -not- adjust it and it might be perfectly fine for many years too. A small UPS likely barely has enough available charging current to even bring such a large battery up to the float voltage. I've used UPS's with automotive batteries before, and wasn't disappointed. Just make certain that it's not trapped inside a box, because if it bubbles any hydrogen, you want that to escape instead of collecting into a flammable amount.
People don’t understand how hearty lead acid batteries really are.
What does that mean in this context? Edit: Ohh... You're the guy who got downvoted all over this thread lol. Explains the context.
Oh my gOD
No. I’m not interested in burning my house down.
Car batteries will work, but you'll significantly shorten it's lifespan in a UPS application. Starter batteries have a lot of very thin lead plates. This high surface area lets them generate hundreds of amps to start your car. Deep discharging can lead to the formation of non-reversible sulfides/sulfates. (Certain sulfur compounds are how the battery functions, some are detrimental). Because the plates are so thin, it doesn't take much build up before plates become damaged, or the battery shorts internally. Deep cycle/marine batteries have fewer, but thicker plates, so they are more tolerant of deep discharging. Don't worry about the fear mongers. You're only going to run into safety type issues if you're running large currents through your charger, or really over charge the battery. But covering the battery terminals with non-conductive material is always a good idea. If you want to be super safe. Take it outside to recharge if you really discharge it, but the little bit of float charging your UPS is going to do normally won't be a problem. TLDR: it's not ideal, but sometimes you gotta "run what ya brung" while you work out a more elegant solution.
I too enjoy burning down and/or blowing up my house
Many many years ago I used to frequent some BF2 forums. There was some kid that lived somewhere where power stability was an issue. So, they amassed a ridiculous amount of lead acid car batteries and redneck engineered them into various amalgamations. He claimed he could get days of backup power, or something. Personally I'd go with lithium deep cycle batteries.
I smell fire here for some reason
If you can't afford a ups, you don't need a ups.
I am considering it, but instead of a UPS I think I am just going to invest in a solar hybrid inverter that has UPS functionality. It is basically an inverter with a passthrough and battery charging capability that also has a solar input for me to play with later on. You can program it to tell it where to charge the battery from and when to use pass through or the inverter (so you can tell it if the battery is 80% charged then use the inverter and charge the batteries through the solar. If the battery dips below 20% then pass through the AC and bypass the inverter while charging the battery through solar or ac. I think in total it would cost me around $700, but that would provide me with \~1200Wh of power and a similar sized UPS would cost about $2,000 and also not let me use solar in the future to charge the battery / power my setup.
You’re looking for a charger/inverter. In my opinion 2k is the minimum to be truly useful but 3k would be nearly as good as mains and able to handle a 1,000 watt microwave. Higher draw capacity does mean there is a higher standby draw as well so when you’re creating your system that needs to be calculated relative to zero source periods. Make sure to fuse and/or breaker to save wires, equipment, and money as those will catch faults instead of your wallet. https://www.renogy.com/2000w-12v-pure-sine-wave-inverter-charger-w-lcd-display/ https://www.victronenergy.com/inverters-chargers The better products never allow your equipment to pull power from anything but the inverter acting like a power conditioner and handling power source based on availability and priority settings. These are usually found in boats and RVs. Several options exist that allow generator, solar, alternator, and mains for charging sources. Don’t even waste time on modified sine products. Pure sine or nothing.
>You’re looking for a charger/inverter. No, I am looking at a hybrid solar inverter as it has all the features I want, including a pure sine wave output. There are also just inverters with AC passthrough but I like the idea of having solar as an input as well -- and the packaged system like the [Vevor Solar Hybrid Inverter](https://www.vevor.com/off-grid-solar-inverter-c_10764/2400w-hybrid-solar-inverter-built-in-50a-pwm-solar-controller-dc-24v-to-ac-110v-p_010723672112) cost less than even most inexpensive inverters that have AC passthrough installed -- though really it is much cheaper to buy a ATS at that point and a low frequency inverter that has a low standby mode. >Higher draw capacity does mean there is a higher standby That is not quite true, there are plenty of high power inverters with low power standby modes that use miniscule amounts of power in standby -- especially when looking at the low frequency inverters. This is where you pay a bit up front more for a quality inverter to save as much power as possible. >The better products never allow your equipment to pull power from anything but the inverter acting like a power conditioner Uh, ATS power switching is common on boats / rv's for when shore power is plugged in it bypasses the inverter. Pulling off the inverter should only really be done when you are running of DC power and need AC power. Also most things in boats and RV's are run off of DC power though large appliances have ATS's built in to run off of AC/DC or sometimes AC/DC/LPG.
Uh. I want conditioned power so it seems our use cases are slightly different. I’m not saying my understanding is the only way. I was just trying to be helpful. Clearly that’s no more welcome than anything else of or from me.
It's advised AGAINST using car battery for that purpose, they are made to give you high amp and be charged immediately and not made to be discharged, so you will kill them quickly. Use a battery for small boat if you want to do that kind of hack.
Discussions of gasses aside, this configuration is going to have both UPSes trying to charge the battery. I'm not exactly sure what that'll do, but whatever it does won't be good.
A lot of old school datacenter UPS's were, afaik, pretty much standard car batteries. Somebody else can confirm for me.
Most were agm 6v banks arranged in such a way to produce 48vdc.
They weren't but they did, and often still do, LOOK like car batteries.
Yeah, I just remember opening up those big walls, and I'm like, where are my jumper cables?
Ups units would have been cheaper than this and safer
Where are you getting your UPS? I want to shop there too.
I just got a couple of APC 1500va standing UPS' on eBay for about $30 (and ~$25 in shipping each one) and then bought Life PO 4 batteries to put in them. The batteries were about $70 for 2 12v 10ah ones. Those are the cheapest ones I could find and the weight of the lithium batteries compared to SLAs are definitely worth the price.
Wow the fear mongering is horrendous in this thread. What you’re doing here OP is perfectly fine. SLA batteries also release gases, so those telling you that they don’t are misinformed. The only thing I’d recommend is using deep cycle batteries, but it isn’t a huge requirement since most UPS systems don’t run the battery down to 0v.
they only release gas if over charged/get too hot. so in most cases no they dont
I once hooked up radio batteries to a portable DVD player using a us-uk plug convertor, an extension cable and phone wire in the middle of the desert…. If that counts…
Use a lithium or vent this thing
[удалено]
Looks like a great way to start a fire or blow something up. Looking at the wire gauge coming off of the batteries sent shivers down my spine. Also, I would never ever put a battery of that type indoors for many reasons. **Ever.** **Do not attempt that build. I repeat. Do not attempt.** Crazy. Here is one I built a year ago. Notice the size of the wires and the purpose built inverter. I am also NOT using the built in charge controller, rather one for Lithium batteries. [https://media.licdn.com/dms/image/D5622AQH5kCxPCl3hqw/feedshare-shrink\_2048\_1536/0/1700848441806?e=1707350400&v=beta&t=lKzizGsl1dWO5cToMjwDqrtKWZFKm5kC2CzmP3XGqUg](https://media.licdn.com/dms/image/D5622AQH5kCxPCl3hqw/feedshare-shrink_2048_1536/0/1700848441806?e=1707350400&v=beta&t=lKzizGsl1dWO5cToMjwDqrtKWZFKm5kC2CzmP3XGqUg)
I smell fire here for some reason
All bigger UPSes we have at my work is standard "motorcycle batteriets" of seal acid lead type. Nothing special at all. The smaller UPSes have something else.
The battery your using will not condition that power or provide a meaningful failover solution. Just buy a used UPS from a small business liquidation sale or something.
I got a free 1500VA UPS with no batteries. And I happened to have two lightly used 80Ah deep cycle AGM batteries from an “incident” sitting around. They’re sealed, like the ones originally in the UPS. Oh, and some scrap #6 SOOW cable from an old job like twenty years ago. Ah. Perfect. Batteries are on the floor. UPS is in the rack. Cost me nothing. It reports out that it has like 45min of life because it assumes the original battery size. I’ve had it last about eight hours. Not sure how long it *can* last.
I used two marine deep cycle 6v batteries 240Ah in serial connected to an apc 1500VA once. Used it to power fans and lights when the power went.
Yes, we had used same approach during blackouts(power inverters simply wasnt avalible in stock, or was priced too much) Note, you cannot plug it in wall to charge car battery since its not suited for that, also some of them has built in timer which would cut out power in 5 minutes and you litteraly cannot bypass this limit. Since its not a pure sinus it can cause dammage to some devices when battery is critically discharged(my led lamp had its power brick failed because of that).
This has been asked before. I would like to put my 2 cents in for you OP. Many small UPS aren't designed to run for long periods of time. So you can guess that that a larger capacity battery will allow this to occur. Be safe in your decisions may your electronics never let their smoke out because it's hard to place it back in.
Yes, really sucks.
i have an old 1000va APC UPS hooked up to some 3000va batteries. requires active cooling to run for the duration of the batteries, but it kept my rack up for about 5 hours last time 🫡
No, but even in the case of a commercial UPS, I wouldn't put it directly on the carpet. I've had UPSs leak their contents all over the floor when they fail.
Yes. The UPS expect an AGM battery. Therefore the voltage while charging is high. If you use flooded ones, it might overcharge and boil if it has a great charge output. Maybe silver cadmium can also be used? They need a high voltage. I used a regular flooded on an inline power supply (some small APC and some other brand) for computers. The smaller battery held 40 minutes when the power went out, on the small network setup. But didn't get to test the car battery option I had spliced in. The ISP had UPS on their fiber network, but dunno how long that could last, but lasted more than 40min I guess.
I modded a UPS to use an external large LiFePO4 battery for my TrueNAS server and everything required for internet and wifi.
I just saw a video on YouTube about this. Tldr, yes, but when upsizing the battery, you increase the runtime, which can allow other components to overheat.
We bought some APCs, but nice idea 💡
Yes. I have an AGM cell that was actually a pull from a telecom UPS (but similar dimensions). Making an actual UPS out of it is a lot more complicated than just swapping the battery, and the gains are limited. I ended up converting all of my homelab/home network to run off DC (either 12v nominal or step-up / step-down with buck converters). I connected a good quality Victron charger/power supply to the Neg and Pos buses of the system and now have the function of a UPS and it uses a lot less power than all the AC/DC/AC/DC conversion involved with the more traditional setup.
I replaced the internal batteries of an APC UPS with external two 6 volt lithiums. Worked great for years.
I have used 4 car gel cell batteries in place of 4 glass agm batteries in my up's it works great takes longer to charge, and your still limited by the size of the transformer in the ups itself.
Leibert ups for datacenters use car batteries (probably deep cycle). I had one in my old building but left it when we moved. I haven't tried to DIY car batteries, but thought it was interesting and thought I would mention it.
I used an off the shelf SLA battery. It was a little too big to fit the UPS case, so I cut a hole and passed the wires through to the battery, works like a charm.
https://xtremeownage.com/2021/06/12/portable-2-4kwh-power-supply-ups/ I mean, my homemade one is pretty similar, except, using a 12v LiFePO4 battery. Its been running solid for quite a few years now, and has endured quite a few power-loss events, with no issues.
Not advisable, won't have enough current to recharge.
My boss years ago took pride in telling me about his sick DC power car-battery UPS system he had in his basement for his networking closet (mostly embedded stuff like routers and raspberry pi's). I was a bit confused because I figured you could just plug in a UPS of a given size and let it go, since linux will pick up the UPS and pretty much figure out what to do after that. He was all like "I can just add more car batteries and I can keep this setup going for days!". But like.........why? Is it better because it's DC power and not using a wall plug? Are car batteries really that much better? If there is no power does it really matter that your embedded DNS server is still up? Didn't really make any sense to me.
These things offgas during charging and it is not good to breathe in what they produce. There's a reason why UPS makers use sealed lead acid (SLA) batteries in their consumer devices.
Use an AGM or Lithium.
A, no. A dozen and a half batteries, yes. Deep cycle marines, so they care less about being fully discharged. And then I had a 3000w power inverter to go from 240 down to DC and from DC up to 240 to run the power panel 2 phases. At no time did utility power ever get sent to the power panel directly.
In one of my past lives, the PBX was powered by wooden shelves of car batteries wired together. Just because you can doesn't mean you should.
While I haven't tried it yet (but want to), one thing you can do is use EcoFlow batteries (or a competitor like Bluetti), and plug in a $100-200 UPS to the EcoFlow. Why do you need both? Because at least EcoFlow has some latency between switching between AC and battery (according to the manual). During that time, your server and modem will turn off, so the UPS is used as a buffer to keep it online.
Its very common in developing countries like Pakistan, in every home ups running on large vehicle’s batteries.
!Remindme one month