Battery powering a PC? Possible?

[RS3RS]

Mmkay, so, I'm getting sick of laptops, so I'm thinking of building a briefcase PC. The only problem is, I would need it to be able to run off of battery power. Weight is something I don't care about at all, I don't mind if the thing weighs 50 pounds. Size obviously does, but not a lot. I might use a second briefcase for the battery or something if I have to.

I'm going to build an LCD monitor into it, so it would need to power that too. I'm planning on building it with components that don't pull a lot of power though (ie: Maybe a laptop hard drive, majorly underclocked CPU, DC power supply or something)...

My thoughts are that if a small UPS can power my desktop + a 19 inch monitor and speakers for 20 minutes, I should be able to power one of those things pretty easy... I would just use a UPS, but those things aren't really meant for continuous battery draining/charging...

It would be nice if I could somehow fit it into one briefcase, but like I said, I could use two if I had to.

So, is it possible?

 

[phasmatis_nox]

A couple high-capacity UPSs seem to be your best bet.

 

[RS3RS]

Originally posted by phasmatis_nox
A couple high-capacity UPSs seem to be your best bet.

Do you think that long-term charging and draining of the UPS would be a bad thing? Or are they built to handel that? I know the power basically goes to the battery and from the battery to the outlets, so the battery is constantly in use, but it's not constantly being drained... Would it harm one to use it like that?

Thanks

Edit: I looked at some more websites, and it looks like the UPS wouldn't be the way to go:

Another problem associated with the battery pickup feature is that even if the batteries are functioning normally failure may occur because of a lack of recharge current. Typically, off-line UPS systems are not supplied with fully-rated chargers. Instead the systems are supplied with a "trickle chargers." These "trickle chargers" are not designed to quickly recharge the systemâs batteries after a discharge. If the batteries are being cycled often, the result is that the "trickle charger" may not be able to fully recharge the batteries in-between discharges. The batteries can be discharged to a state from which they can no longer supply the required current to your critical loads. Not only does this damage the systemâs batteries, but it will also drop critical loads.

So.. Any other ideas?

 

[Elledan]

I would use one or more deep-cycle batteries, a 12 V PSU and an EPIA M10k board. Definitely stay away from inverters, as these produce a lot of heat (wasted power). The EPIA board uses only 10-15 Watt at most.

UPSs contain a battery charger, a (sealed) lead-acid battery and an inverter, in addition to other components. It's better to construct something yourself.

Lead-acid batteries last about 600 cycles (charge/discharge).

 

[RS3RS]

Originally posted by Elledan
I would use one or more deep-cycle batteries, a 12 V PSU and an EPIA M10k board. Definitely stay away from inverters, as these produce a lot of heat (wasted power). The EPIA board uses only 10-15 Watt at most.

UPSs contain a battery charger, a (sealed) lead-acid battery and an inverter, in addition to other components. It's better to construct something yourself.

Lead-acid batteries last about 600 cycles (charge/discharge).

That sounds like the way to go, I'll probably end up doing that...

The only thing I'm not sure on, is where to get the batteries... I mean, I could use a deep-cycle car battery (and I may), but it would be nice to have something a little smaller... Any ideas?

Thanks for the help.

 

[AnubisPrime]

Well I don't know if its of any help, but you might try looking at deep cycle batteries made for trolling motors on boats and stuff like that, I know they make models smaller than a car battery

 

[Elledan]

Originally posted by RS3RS
The only thing I'm not sure on, is where to get the batteries... I mean, I could use a deep-cycle car battery (and I may), but it would be nice to have something a little smaller... Any ideas?

This page might be useful: http://www.dansdata.com/diyups.htm

 

[m1abram]

You want SEALED dry cell lead acid batteries, gel cells may work for you however dry cell are much less likely to cause you issues with leakage. The gel cells are a bit better for deep cycles though, but not much.

Remember if this is something you are going to be carring around, then you want a battery that can take some falls and can be oriented in different positions. Gel cells and liquid cells do not work well in these conditions.

Another place you can grab batteries is from an UPS, and discharge the rest. Those are normally dry cell 12V lead acids.

Things to think about though beyond the batteries, you will need a GOOD charger. No faster way to kill batteries is with improper charging. Also venting is important, I know the say sealed, but should something go wrong the battery will blow if pressure relief valve and you want the escaped gas vented. Also temp. affects battery performace a great deal both during discharge and charging. Also affects the lifetime of the battery.

Plus 50 pounds of battery will NOT last long with a modern CPU and highend graphics card (i suspect that is what you do not like about laptops). You may get about 1 hour of uptime with 50 pounds of lead-acid batteries. And the life expectancy of those batteries given good care will be about 18-24 months if used frequently for deep cycles.

edit: I would strongly recommend not trying to self power a full PC, if self power is a requirement then I would get a laptop. I can not see the advantage of lugging that much gear around, two briefcases with one filled with batteries is a lot of heavy gear. However a briefcase PC with everything BUT power is a great idea and can see that as very handy. Course I have no idea what you application needs are so that is just my opinion.