Car battery to power PC?

mckgarth · May 17, 2017

I have an Asrock J3710-ITX with a Samsung 850 ssd and 1 4gb & win 7 32bit and run 3 monitors. I want to power this PC with a PicoPSU-120-WI-25 and a car battery and keep a 1.25 or 1.5amp Battery Charger/Maintainer on it but am worried that the charger will put out dirty power (too much ripple?) I don't want to shorten the MB life because of bat charger. any thoughts?
thanks, Garth

Gam3r01 · May 17, 2017

Why on earth would you want to do that?

Paperdoc · May 17, 2017

You need some recalculation. If this device will deliver up to 120W (short-term max) at 12 VDC, then it is delivering up to 10 Amps. Assuming 75% efficiency, it can consume up to 13.3 amps, and at "normal" output of 80 W, it will consume 9 amps. If you're using a battery charger of 1.5 amps capacity, your battery will go dead fairly quickly. You would need a battery charger of at least 15 amps capacity, plus the battery, plus this PSU module. The combined price will be more than a normal computer PSU.

You have not addressed whether this module is sufficient for the mobo requirements. That requires detailed study of the current requirements of the mobo (with your hardware components installed) for each of the main voltage supplies, and comparing that to the actual output capacity of the PicoPSU module. Without doing that you cannot be sure it will work. The mere fact that this module says it is a PSU suitable for ATX mobos does not tell you nearly enough.

g-unit1111 · May 17, 2017

Why would you want to do this? Just as an experiment to see if it works?

Onus · May 17, 2017

This could be for an off-grid or emergency environment. The biggest issue I see is that a "car battery" (a starting/lighting/ignition battery) is not designed to be deep-cycled, and will be killed in a matter of weeks this way.
What you probably want is an AGM battery, that is designed to be deep-cycled (still best not to go below 60% SOC).
Assuming the battery is always in the circuit, you will not need to worry about ripple from the charger; the battery will smooth that right out.
Each of your three monitors will consume power also, and will most likely require an inverter (unless you have found some with a 12V input). Inverters have losses, so take them into account when sizing your battery. A little more information as to your goals might be useful. A laptop might be a better choice for low power use. There are laptop adapters that plug into 12V sockets.

mckgarth · May 18, 2017

Thanks everybody for the replys
I plug monitors into the wall, just want to power pc with batt. I thought pc would only use maybe 20w max?
The CPU is rated at 6.5watts, onboard video only, and I don't use dvd player so only power consumption is ssd, cpu/mb/memory
Can't find info on energy use for both cpu/mb
currently using corsair hx620, love the corsair but way more than needed
would like to keep sources of heat out of the pc case (ac/dc converter of ps)
also coming stormy season,(central fla...much lightning) rural area, lots of short power outages, want to protect ssd from damage, and yes I am on APC battery backup-still
So I thought a car batt with very low amp(1.5?) charg could power this for 24hr service (dedicated trading PC, MT4 is an older trading platform and uses very little resources)
Also very dusty environment for laptop-thats why I like no fans
I've also considered a Seasonic ssr-360gp plus gold -I'm using an atx case...can't find quality low wattage atx power supply's.

mckgarth · May 18, 2017

Sorry, 1 more thing, I was hoping the charger would put out enough power to keep the batt from discharging so as to not need a deep cycle battery. I believe a batt maintainer/charger starts charging at about 12v and charges to 13.something v

Someone Somewhere · May 18, 2017

At 6.5W max for the CPU alone, you might be OK with the 1.5A charger, but IMHO only just. The rest of the PC will also draw load, especially the SSD - that can be a couple of watts. USB devices could also draw quite a bit, especially if you plug a cellphone in or something. You want something like a 5A charger, at least. Aim for a tenth of the battery capacity in amp-hours.

I was hoping the charger would put out enough power to keep the batt from discharging so as to not need a deep cycle battery.

If you do end up discharging the battery, this could be an issue.

Also, only the leftover capacity from the battery charger will go into charging the battery. If the PC's pulling 1.2A, there's only 0.3A going into the battery. That could mean it takes a week or more to fully recharge.

I'd recommend getting a good case with dust filters, setting it up to be positively pressurised, and cleaning the filters regularly. Dust is still going to accumulate on that heatsink, even without a fan.

Paperdoc · May 18, 2017

20W is a VERY low power consumption for any system. Before you start designing your system, you really need to KNOW what the actual power consumption of the complete system will be - both average and peak.

Someone Somewhere · May 19, 2017

Paperdoc :

Did you look at the motherboard he's proposing? It's basically a netbook without a screen, perhaps less.

6.5W TDP CPU with integrated chipset and GPU, no fans, HDD or ODD, so you're really looking at that, an SSD, and two sticks of RAM.

wbonville · May 23, 2017

Battery chargers have come a long way from 1/4 to full wave rectfication. Chargers are now smart and can detect the type of battery you have. For your retirements you may want to do a little research. Full wave rectifier cleans up all the power. Smart chargers will control and limit the current required and keeping voltage at 13 - 14 vdc.

Someone Somewhere · May 23, 2017

Full wave has been around pretty much as long as half wave; it just means a little more parts cost. Still horrid output; lots of the original sine wave. I would also be pretty surprised if anyone was still using mains-frequency transformers due to size, weight, and cost. So you're probably dealing with high-frequency ripple too.

That 13-14V is about 3.5x outside what the ATX spec allows.

ratherbeflying · May 24, 2017

My solution would be a small Honda portable generator. They're very quiet to help keep the zombies from you and will run for quite a while on a small amount of gas. A little pricey, but well worth the price. You could even use it with a blender to make frozen beverages for the zombies should they find you.

Someone Somewhere · May 25, 2017

Not so good an idea inside, and you've still got to start it so there's still a short power cut. UPS, I guess...

I'd suggest pair of big deep cycles in series (24V) and a regulated buck converter or an inverter - but seems a little pointless given he wants to leave the displays on mains power.

Smlarkin · May 25, 2017

mckgarth :

Smlarkin · May 25, 2017

mckgarth :

Thanks everybody for the replys
I plug monitors into the wall, just want to power pc with batt. I thought pc would only use maybe 20w max?
The CPU is rated at 6.5watts, onboard video only, and I don't use dvd player so only power consumption is ssd, cpu/mb/memory
Can't find info on energy use for both cpu/mb
currently using corsair hx620, love the corsair but way more than needed
would like to keep sources of heat out of the pc case (ac/dc converter of ps)
also coming stormy season,(central fla...much lightning) rural area, lots of short power outages, want to protect ssd from damage, and yes I am on APC battery backup-still
So I thought a car batt with very low amp(1.5?) charg could power this for 24hr service (dedicated trading PC, MT4 is an older trading platform and uses very little resources)
Also very dusty environment for laptop-thats why I like no fans
I've also considered a Seasonic ssr-360gp plus gold -I'm using an atx case...can't find quality low wattage atx power supply's.

Your

Smlarkin · May 25, 2017

mckgarth :

vankilu · May 26, 2017

You really need to measure/know the maximum watts(measure with this affiliate link removed used over 24hrs to design a solution. An uninterruptible power supply with a large capacity will simplify clean power charging concerns, I ran a 750VA APS uninterruptable power supply(cut the warning beeping circuit) off 2 12volt scooter batteries for 4 years then a group 27 deep cycle battery another 6 years. I had a 40" plasma screen, a TV satellite receiver, a Hughes internet satellite and 2 laptops, about 700 watts. plasma and TV satellite ran about 420 watts. During our Arizona monsoon and snow seasons we frequently have surges, brownouts and power outages it worked flawless. I am not sure how you intended to run your computer on 12 volts DC as you will also need +5 volts +3.5 and -3.5 volts, which can be done by adding regulating electronics. As for a small power supply, it will only consume/Produce wattage your computer requires. I.E... you can have a 450watt power supply, if your system only requires 110 watts to run, that's all it will draw, 110 watts not 450watts.

Someone Somewhere · May 26, 2017

Read the OP. Go look up what a PicoPSU is.

A kill-a-watt will not help you measure current/power at 12VDC.

Mousemonkey · May 26, 2017

The posting of affiliate links is not allowed. :non:

Smlarkin · May 26, 2017

A car battery will provide plenty of filtering for noise, but would be better for a laptop running on 12volts because
a desktop would need an AC inverter. Bear in mind that at 110 volts a computer may draw an amp of current but
at 12 volts it will take 10amps. A one amp charger will not be able to keep up with continuous demand even
though it will recharge the battery when the computer is not using it.

Car battery to power PC?

Prominent

Titan

Polypheme

Titan

Titan

Prominent

Prominent

Titan

Polypheme

Titan

Reputable

Titan

Prominent

Titan

Reputable

Reputable

Reputable

Distinguished

Titan

Titan

Reputable

Share this page