Has anyone powered GPUS with a car battery?
Posted by TooManyPascals@reddit | LocalLLaMA | View on Reddit | 42 comments
Time for a question my dear ChatGPT doesn't want to answer me... how to power GPUs from a battery.
The point of course is that my office can't provide the 4.5kw peak power that my GPUs ask, and I was considering to leverage the very high peak amp delvery of a lead acid battery.
I know GPUS want clean 12V, and car batteries provide between 12.8 and 14V, but the 12V of the GPUs go to a DC-DC converter anyways, and probably can ingest anything between 8V and 16V, but before I burn a few GPUs trying, I'd like to ask if anyone has given a try.
tired514@reddit
Assuming cost is (less) of a concern, why not just grab an Ecoflow Delta 3 Pro?
If you really want to keep it DC-only I'd go with a 48V / 100Ah lifepo4 server rack battery with a few large 48V -> 12V buck converters ganged together. Last thing you want is a lead-acid undervoltage that drives the current way up, imho.
ProfessionalSpend589@reddit
I have little experience with River 3 Plus and when it’s connected to AC (wall) it passes the charge directly to the equipment.
If OP’s office can’t handle 4.5kW, then I suspect the Delta 3 Pro also won’t be helpful unless it’s being charged only by one of the other methods (photovoltaic panels or car charger connected to wall which will pull a 100W or so).
Glad to be corrected if I’m wrong on this topic :)
tired514@reddit
Damn.. good catch. I thought the grid bypass mode was an online UPS but apparently not, sigh.
Guess a 60V/20A chargeverter might be a workaround, but that's pretty annoying.
Thomas-Lore@reddit
Those power stations should not be used near that peak power. I had to send mine for repairs because I switch PS5 to PS5 Pro, peak power during turning everything on was higher and the inverter broke.
Charming-Author4877@reddit
It is likely a lot easier and cheaper to fix the grid so the 4.5kw peak can be supplied.
A electrician can probably fix the issue at a fraction of the cost of a battery.
mxforest@reddit
If you don't mind me asking, what is the point of keeping GPUs in a specific location? Why not keep it somewhere that has clean power and connect it over a VPN or something? Still secure and local. Only scenario I can think of is that Internet is non existent. But what are you doing with these many GPUs in a location like that?
TooManyPascals@reddit (OP)
I have an agreement with my wife. I can do whatever weird experiment I want, as long as it is contained in my home-office. :)
DeltaSqueezer@reddit
Best plan is to fix this:
Upgrade the electrics.
bucolucas@reddit
Yeah if he's having trouble providing clothes dryer-tier wattage that's a different problem
ga239577@reddit
I have run a desktop computer with 1 GPU through a pure sine wave inverter attached to a AGM battery bank - I assume it would work fine if you had a big enough power bank and big enough inverter.
Baldur-Norddahl@reddit
Just get a -48V DC PSU that are made for telcos. They use DC in exactly this way. Lead acid batteries chained to get 48V and equipment is connected directly to the batteries (with a fuse!). The charger is also permanently connected and charging. During a power outage the charger just stops charging and the equipment never notices. No fail over or anything complicated.
Just be aware that the voltage is not dangerous to the touch, but the amps will make any short circuit look like a welder and can easily start a fire or hurt you with molten metal. Proper fuses are needed.
Thomas-Lore@reddit
Lead acid batteries will not last a year used like that.
Baldur-Norddahl@reddit
Here is a picture of a -48 V DC lead acid battery system at a telco facility.
lordofblack23@reddit
That is not a car battery
Baldur-Norddahl@reddit
It is a very large car battery. Exactly the same thing going on. Lead plates with acid. Aside from the size, the other interesting thing about it, is that it is built of individual 2V cells instead of 6x2V in a shared casing like 12V car battery.
Also it is old fashioned lead acid with fluid. Most new car batteries use some solids to avoid the fluid.
Baldur-Norddahl@reddit
Telco facilites use the same batteries for 50+ years topping up the fluid regularly.
segmond@reddit
"The point of course is that my office can't provide the 4.5kw peak power that my GPUs ask, and I was considering to leverage the very high peak amp delvery of a lead acid battery."
So you call the electrical company and get more watts dropped in to the office.
mattate@reddit
Lead acid batteries create flammable gases, they don't belong in an office. If your only option is batteries look at lithium iron phosphate, or something safe to keep indoors.
outdoorsgeek@reddit
I don't have an answer. But I want to see how this story turns out.
StarshipCherry@reddit
bro is running y'allama.cpp
hurdurdur7@reddit
Have you even checked that you need to do the dc dc conversion at 60-100 amps? That is not a cheap thing to do.
StableLlama@reddit
Specification of the 12V: https://edc.intel.com/content/www/us/en/design/products-and-solutions/processors-and-chipsets/alder-lake-s/atx12vo-12v-only-desktop-power-supply-design-guide/2.11/dc-voltage-regulation-required/
=> +11.20 V ... +12.60 V is the valid range
You can do whatever you want, as long as you guarantee that voltage rage. Even under load (-> internal resistance)
The easy route is to use an inverter to convert the 12V battery to normal AC (first world 230V, third world 110V) and then use a regular power supply.
The technical advanced but more efficient route is to use a DC/DC. Won't tell you more about that, as there are many things you need to know - so when you know those things already I don't need to tell you, and when you don't it's far too much for a few postings. And chances of electrocuting you or someone else is high, burning down the house even higher.
And when it's a commerical setting (office), then there's only one option: get a qualified electrician to fix the power supply of the office. And perhaps also a qualified climate technician to work out a plan to remove the excess heat this thing is generating from the office. An electrical heater uses less power.
rog-uk@reddit
If you are in a big office, maybe in the comms/server room? We used to have 240V 32A outlets.
GatePorters@reddit
How do you charge the battery?
screenslaver5963@reddit
Car /s
Soggy-Eagle4657@reddit
That's interesting. Please let us know what it turns out to be.
matjam@reddit
Fire. It will turn out to be fire.
SomewhereAtWork@reddit
Don't try to connect the batteries directly to the GPUs. That will be a mess.
Get a solar backup battery or a 220V camping inverter. Use batteries to get a stable 220V supply, use it to power the PSU of your workstation.
PrinceOfLeon@reddit
That sounds like a UPS with extra steps
Still-Wafer1384@reddit
More like a UPS with much more capacity.
Thomas-Lore@reddit
There are now lifepo4 power stations that are basically that.
export_tank_harmful@reddit
You'd need something like one of these.
They're about $2k.
The JK BMS in those batteries has a 200A rating and the batteries run at 48v.
That'd get you around 10kW of continuous output.
The issue is charging it at that rate to compensate for the draw.
I have around 50 "older" panels (some 100w, some 200w) and that many panels total adds up to around 10kW.
Each panel is around 5ft x 3ft. It'd be a massive footprint to actually deploy all of them.
Granted, "newer" panels are more efficient for their size, but yeah.
Just a very rough ballpark for this sort of thing.
Dr_Allcome@reddit
Most UPSs will expect the input power to be the same or higher than output power and are very single mindedly designed to keep the load running. So if your battery runs low while power input is detected it will usually switch the load through to keep it running, and in OPs case, blow the breaker.
Camping solar batteries are designed with a more varied input in mind, to charge from different low power sources and to not overload those.
SomewhereAtWork@reddit
Yes, a UPS would also totally do the job.
PathIntelligent7082@reddit
bcs the guy is looking for something like ups
SnooPaintings8639@reddit
Wait. A car battery as in office power use? I think your office administrator might want a chancetwith you.
spambait-aspaaaragus@reddit
This js such an odd situation
ImportancePitiful795@reddit
The safest method, is to get an electrician and pull a line for heavy duty appliances which are rated to 7kw.
Do not connect your PC to car battery. You will just lose everything.
Cyberbird85@reddit
This feels like a temu version of xkcd’s what if
Double_Cause4609@reddit
So...I haven't tried to do this specifically myself, but I do have a friend with a cabin. He used to power it with car batteries, because "well, they're just so cheap". Anyway, he had to replace them every year (sometimes more than once) because if you put them out of the 30% - 70% happy place, they degrade super rapidly.
I'm not saying "don't do it", but I am saying that I've been down this line of reasoning with someone else and it's not as clean a match as you think it is.
Lead acid batteries are also unsafe to use indoors (unless you get the fancy self sealed ones that aren't far off in price from a good sale on a lithium iron phosphate anyway), and they're less stable for fine grained electronics like GPUs (and trust me, with a setup like I suspect you have power fluctuations do matter a lot).
alex_tracer@reddit
I wouldn't expect more than 400-500 watts of consistent output from single car battery.
DependentSlow2850@reddit
Lead Batteries are not made for such sustained power loads. EV batteries are better but an expensive ask. Others are not really worth it. I guess if you really really wanted to, I would recommend EV batteries for a bit. Lead will give you poor compared to just buying a proper setup. But really, you main concernation is stabilizing that power. I would hard no this.