psu powered by battery

[Cary small]

Hello everyone, I have recently build a computer in a briefcase(screen and everything in the box as well) so it is effectively a large laptop. Everything is working except it doesn't have done a battery. I have 2 laptop batteries lying around, would it be possible for me to mod one of these batteries to power my psu?

Thank you.

 

[Phillip Corcoran]

You can't power a PSU from a battery as the PSU needs AC mains power as clearly shown on it's rating plate.

 

[spdragoo]

You would have to hook the laptop battery(ies) up to a DC-to-AC power inverter. This website has some examples of a number of different types:

http://www.dcacpowerinverters.com/12_volt_power_inverters.html

The problems that you'll run into:

1) Most of the inverters are hard-wired to run from a cigarette lighter outlet in a car. A few of them have alternate inputs (i.e. at least one also has available car battery clamps; another has wiring terminals instead), but in the main the biggest problem is that those connectors aren't compatible with laptop battery connectors. Which means you'll have to MacGuyver something together so that the batteries can transfer power.

2) While the inverters aren't super-expensive (I think they all were under $100 on that site), you have to make sure the inverter can power your briefcase PC's PSU. A lot of those inverters are very low-power -- 100-200W sustained, 200-400W peak. Yeah, they had a couple that were very high-end ($88 for one that could provide 750W sustained/1500W peak), but you start getting into size issues (that one weighed 6 pounds). Hopefully you don't need more power than that, as they start heading into $200-$300 price ranges beyond.

3) You need to make sure your laptop batteries can provide enough juice. Those inverters are set up to receive 12V average, 10-15V min/max range of input (below 10V or above 15V & they shut down). So you'd have to make sure your laptop batteries provide the right type of input.

4) Finally, you need to worry about lifespan. Laptops are all about saving power: their CPUs are invariably low-power versions, the RAM chips are smaller so they use less power, the GPUs are "mobile" versions that draw less power, etc. That's why Surface tablets with full x86 chips have less battery life than ARM-equipped Surface tablets (ARM chips use less power than a standard x86 chip). So, a battery that might last 4 hours in a laptop might only be able to provide power for an hour for this briefcase PC.

In short, if you have the electrician skills and money to wire it up, it's possible...but you're not only going to drastically cut into the portability (what with lugging a heavy power inverter along plus all the spare laptop batteries), you're going to end up with a PC that's just as big (if not bigger) than a tower PC.

I would say, just the fact of having a portable tower like that is achievement enough, & maybe just making sure you have a 30ft extension cord as a backup.