Using car battery to run your PC?

[Totallycasual]

I live fulltime in my campervan and run my PC and Playstation off of a 12 volt battery bank (2x 120AH lithium).  Starter batteries aren't much good for that type of thing though, they're all about high cranking amps, very short term draw.

 

If the sun has been out a lot through the day and my batteries are full, i can game on my PC or console for a good 4-5 hours in the evening if i'm in the mood for it. 

[DavidKalinowski]

12 hours ago, Chiyawa said:

Not sure what is CCA, but my battery type is automotive battery found in diesel/gasoline engine type cars and trucks. The battery brand is Panasonic, has 17 plates, and with capacity of 68A. That's all I know about the battery. I just change the battery as it is getting weak and couldn't start my truck, but I think it still can serve for other purposes. Battery health is at 60%.

 

Hmm... I wonder where you can get this type of battery... Anyway, I live in Malaysia, so this type of battery is not commonly available.

CCA is the cold cranking amps, thats the power of the battery to turn over your starter motor, its the reason you bought a new battery. Chances are that battery is not going to hold a charge much longer, its wearing out. Also not really designed for being used as back up power.. you would be better off getting a real battery back up solution..

[Darth Wilhelm]

Here's a video on the topic

Granted it's more in the context of a battery backup but the concept should still be the same.

[Chiyawa]

On 10/10/2020 at 12:42 AM, DavidKalinowski said:

CCA is the cold cranking amps, thats the power of the battery to turn over your starter motor, its the reason you bought a new battery. Chances are that battery is not going to hold a charge much longer, its wearing out. Also not really designed for being used as back up power.. you would be better off getting a real battery back up solution..

Yeah, I know it's wearing out. But thought it would be a good idea for the battery to spend their last remaining of their life doing something useful before we throw it away (This battery is not cheap, as it is larger than ordinary car battery).

 

Thanks for the advise.

[Chiyawa]

On 10/9/2020 at 7:34 PM, Totallycasual said:

I live fulltime in my campervan and run my PC and Playstation off of a 12 volt battery bank (2x 120AH lithium).  Starter batteries aren't much good for that type of thing though, they're all about high cranking amps, very short term draw.

 

If the sun has been out a lot through the day and my batteries are full, i can game on my PC or console for a good 4-5 hours in the evening if i'm in the mood for it. 

Indeed. Lead acid battery are not really ideal for the constant variation of power draw from electronics. But well, I mean I have a car battery lying around, so thought of instead letting it rot, I might use it until its totally dead. It still retain quite good charge, and it still has (according to battery tester from a mechanic) 60% health left. Certainly not able to start a car, but still can power up some small electronic device.

 

Hmm, Nice, 2x 120AH battery. Is the lithium type as big as the lead acid one? I saw a 120AH lead acid battery, and man they are very huge!

[Moonzy]

you can get 12v 100Ah deep cycle batteries for ~RM700-ish from jalan pasar iirc

and grab a good inverter above your full pc setup's wattage and you should be good to go

 

though... what PC are we powering here? because 12v 100Ah is ~1200Wh

which is ~2-3 hour of full load for normal gaming desktops, including monitors

a laptop could last way longer, if it's <150W models.

 

also, you'll need a way to charge the battery

[Chiyawa]

On 10/10/2020 at 12:50 AM, william axton hylle said:

Here's a video on the topic

Granted it's more in the context of a battery backup but the concept should still be the same.

Yeah, hard to get a car inverter that could provide 1000W of power. Most of the car audio specialist and repair shop in my area only carry inverters as high as 600W. I know modern buses used a higher powered one, but it's pretty much difficult to get by.

[Moonzy]

1 minute ago, Chiyawa said:

hard to get a car inverter that could provide 1000W of power

you wont get ones for cars because there's a 10A fuse for cigarette plugs

you can find those that connects to batteries directly

i have a 1000W and 3000W unit, ordered online

though... idk if i would feel comfortable plugging my PC into those coz even my fan's motor makes a weird sound when it's running

prob not a perfect sine wave inverter

[ausham]

I did this before with a little low wattage via C3 system and a pico psu. Worked fine until the battery got low and the system became unstable.

[Kisai]

5 minutes ago, Chiyawa said:

Yeah, I know it's wearing out. But thought it would be a good idea for the battery to spend their last remaining of their life doing something useful before we throw it away (This battery is not cheap, as it is larger than ordinary car battery).

 

Thanks for the advise.

Basically this is not really a good path to go down for a PC. At best you could power a 45-120w laptop using a DC-DC adapter. Believe it or not, this kind of question comes up quite often on the forum, and the general answer to "can I use a desktop/gaming PC with my RV/Boat (that runs off a 12V battery/while the engine is running)" is "don't bother", the complexity of trying to use it doesn't justify the inevitable equipment damage.

 

What you might try, if you're willing to risk a UPS, is to hook the battery up directly to the UPS. However there are still requirements beyond this, and a 12V battery that isn't holding a full charge is not good for this anyway.

 

My opinion here is that you may want to just use it to power 12V LED lights or something.

[Chiyawa]

2 minutes ago, Moonzy said:

you can get 12v 100Ah deep cycle batteries for ~RM700-ish from jalan pasar iirc

and grab a good inverter above your full pc setup's wattage and you should be good to go

 

though... what PC are we powering here? because 12v 100Ah is ~1200Wh

which is ~2-3 hour of full load for normal gaming desktops, including monitors

a laptop could last way longer, if it's <150W models.

 

also, you'll need a way to charge the battery

Thanks for the info. I live in Sungai Buloh, but quite often, the time is not on my side. I'm only free at Sunday (which most of the shops are closed during that day), so it's a bit difficult for me to obtain electronics parts and gadgets.

 

I have a small battery charger, and it took about 10 hours to charge the battery to full.

 

What I really need is a high powered inverter. Many of the car audio specialist shops only carries 300W and 600W. Rarely saw a 1000W one.

 

My PC used around 700W at full load, and from the PSU input, sometimes it can go as high as 850W or close to 900W (that is when everything is maxed out). So yeah, not expecting my battery to last very long either if I'm gaming. I will only use for office work and entertainment most of the time so not consuming that much power. Monitor used around 35-50W.

 

This thread was created because I have an old used car battery lying around, and thought it would be a good idea to make it as a temporary power source in case power is out for a while (like lightning storm), which happens quite frequently these few days.

[Moonzy]

8 minutes ago, Chiyawa said:

What I really need is a high powered inverter. Many of the car audio specialist shops only carries 300W and 600W. Rarely saw a 1000W one.

could try order online

though it's good to see how much wattage you require first

 

8 minutes ago, Chiyawa said:

My PC used around 700W at full load, and from the PSU input, sometimes it can go as high as 850W or close to 900W (that is when everything is maxed out). So yeah, not expecting my battery to last very long either if I'm gaming. I will only use for office work and entertainment most of the time so not consuming that much power. Monitor used around 35-50W.

at this point im more concerned for your battery's health because that's ~70A of continuous current, best figure out of your battery can deliver that load safely

i really dont recommend using a car battery for this, let alone a dying one

it's just not designed for continuous load

 

8 minutes ago, Chiyawa said:

This thread was created because I have an old used car battery lying around, and thought it would be a good idea to make it as a temporary power source in case power is out for a while (like lightning storm), which happens quite frequently these few days

get a UPS

one that can hibernate your PC in case of power loss is also good if you need such feature

you wont get much uptime, but at least work wont be loss

 

dont think your project will be a good idea, overall.

i dont even recommend people keeping 12v 100Ah battery just to play games for occasional blackouts, sounds excessive.

battery dont age well.

[Chiyawa]

19 minutes ago, Moonzy said:

get a UPS

UPS has small battery even if they can supply continuous power for 15 minutes. Installing a larger battery pack cost a lot, and many home and office UPS doesn't have battery extension. Not sure if I can just plug in the car battery just to make it last longer.

 

23 minutes ago, Moonzy said:

i dont even recommend people keeping 12v 100Ah battery just to play games for occasional blackouts, sounds excessive.

Indeed. That cost close to RM700 or more (My 68AH battery cost RM525). Sill, it's lying around, thought I could put it o good use.

 

37 minutes ago, Kisai said:

My opinion here is that you may want to just use it to power 12V LED lights or something.

I have a small 12V truck fan and am using it right now. Still, I felt it still has a lot of potential to turn into backup power in case of power outage.

[Moonzy]

Just now, Chiyawa said:

Not sure if I can just plug in the car battery just to make it last longer.

hmm... i would lean on best not

 

1 minute ago, Chiyawa said:

I have a small 12V truck fan and am using it right now. Still, I felt it still has a lot of potential to turn into backup power in case of power outage.

my 100Ah is hardly enough for 2 night of lighting for camping trips, not sure how useful is your 60% alive 68Ah battery.

[Chiyawa]

29 minutes ago, Moonzy said:

my 100Ah is hardly enough for 2 night of lighting for camping trips, not sure how useful is your 60% alive 68Ah battery.

Yeah, just need for a couple of hours, probably 2 or 3 hours or so.

 

32 minutes ago, Moonzy said:

hmm... i would lean on best not

Yeah. Any modification will void the warranty. UPS is also expensive as well. Not going to mess with them.

 

Still, if looking at UPS, most consumer doesn't last very long. Industrial grade one however cost a fortune.

[Moonzy]

1 minute ago, Chiyawa said:

probably 2 or 3 hours or so

you're not gonna get that out of your battery

with your proposed load, i would be surprised if it lasts 30 minutes.

[Totallycasual]

2 hours ago, Chiyawa said:

Is the lithium type as big as the lead acid one?

They're actually the same size as normal car batteries but they weigh a lot less (and cost a lot more too, $850 each for the ones i have). 

[Chiyawa]

20 hours ago, Totallycasual said:

They're actually the same size as normal car batteries but they weigh a lot less (and cost a lot more too, $850 each for the ones i have). 

Wow. Hmm... I see. Looks like it's still hard to DIY a UPS out from it will be expensive.

[Chiyawa]

21 hours ago, Moonzy said:

you're not gonna get that out of your battery

with your proposed load, i would be surprised if it lasts 30 minutes.

Well, I won't be utilising full load, so should be suffice. When I'm just using my PC for office work, I found out that I only used up to 250W at most. So, the dying battery still can provide good deal of power, at least for an hour, if I'm only doing office work.

[Moonzy]

4 minutes ago, Chiyawa said:

Well, I won't be utilising full load, so should be suffice. When I'm just using my PC for office work, I found out that I only used up to 250W at most. So, the dying battery still can provide good deal of power, at least for an hour, if I'm only doing office work.

assuming it's truly 60% of it's original capacity

you're looking at 0.6(12 x 65) ~= 468Wh

which will last you ~1.5hr-ish

 

again, I'm not sure how would a car battery handle continuous load.

and how are you planning to connect to it? when powers is down you would connect your pc to it manually by switching plugs or?

and remember about your networking gear if you need those (though those might be out as well on the ISP side if it's your entire area having a blackout)

[Chiyawa]

3 minutes ago, Moonzy said:

assuming it's truly 60% of it's original capacity

you're looking at 0.6(12 x 65) ~= 468Wh

which will last you ~1.5hr-ish

That's my original idea. My 800VA couldn't last 10 minutes even when I'm doing office work, and it can't even run my PC when I'm about to play games (the maximum output is only 600W). Usually, by day time when I'm not gaming, I'll plug my PC to the UPS since I'm doing office works, and at night time when I want to game, I have to shut down the PC, remove the plug from UPS and plug to the main power line.

 

I'm also thinking of buying the inverters from car audio specialist, hoping to find a 1000W one if possible.

 

Well, since gaming might be out of option, at least when the power is out, I can still do some office works with a backup power utilising the dying battery. It's only a short term workaround, but if this prove to be a success, maybe I can start investing to a more better battery option. Thinking of installing industrial 10kVA UPS, very expensive, it may as well suit me, but the battery run time still quite poor and won't last very long, and the fact that the power frequently trip only when in raining season, it's not really worth to buy one.

 

6 minutes ago, Moonzy said:

though those might be out as well on the ISP side if it's your entire area having a blackout

Yeah. TM just sucks. But I'm using Maxis Mobile (my area doesn't have fibre optics connection, for heaven's sake) so usually I still be able to go to Internet even when my whole area blackout.

[Moonzy]

Consider using a backup generator too, if your power requirements are high and switching time isn't of concern

[Chiyawa]

1 hour ago, Moonzy said:

Consider using a backup generator too, if your power requirements are high and switching time isn't of concern

Thanks. I'll consider that. Still, it is quite noisy and since it's a residential area (WFH soon), the noise might be of concern. I try to avoid generator if possible, but if generator is the only viable option, guess it can't be help.

 

Now, looks like I might need an AVR to smooth out current output of the generator.