Keeping the computer powered on...

**boxzer** · 02-08-2006, 07:12 PM

This is my first post here. I have been reading this forum for the last year or so. I've been planning my system for a long time. I am going to have an in dash LCD, via main board, cf harddisk, haven't decided linux vs windows yet. Of course I'm going to have GPS, Music, Video/DVD, ECU Readings, HVAC control, Backup Camera... all the goods. I have EVDO in my area so I'm going with that for Internet connection (dedicated PC Card). Feels like I have it all figured out, except... I want it to be "on" all the time. I want to be able to access my computer without turning on the car. I want to have a battery capable of powering the unit for 12-24 hours before it "hibernates" then recharges when I'm driving. I know this might sound weird, but I think you can add addn'l capability if you have the computer on all the time. I'm a computer programmer not an electrician. My knowledge of "power" is very limited. Looking for good suggestions, I think this is the right forum!

**DarquePervert** · 02-08-2006, 07:29 PM

You're going to need a trunk full of batteries.
OK, I might be exagerrating a bit. A second battery and a low-power laptop might be able to stay on for that length of time.
You're going to run into a couple issues, though.
As the battery drains and is recharged, it will lose storage capacity. It's the way batteries work. This means that over time, you're going to be able to leave teh comptuer running for shorter and shorter periods.

I think your goal is attainable, but not without some careful engineering of the power situation. And even then, I don't see the practical purpose of leaving it on all the time.

**daPyr0x** · 02-08-2006, 07:57 PM

Deep cycle batteries are made for that kinda abuse, so if you had a two battery setup with an Optima Yellow Top (deep cycle) it's possible to do something like that, but not incredibly bright. I mean, you could use a relay to isolate your two batteries so your second one would charge and your first wouldn't drain when you leave the computer on.

A smarter idea would be to have an alarm or starter installed in the vehicle and have an auxiliary output go through a latching relay to the remote turn on lead of your setup. Thus, you could remotely turn on the computer with the button on your starter/alarm remote and being a programmer I'm sure you can figure out a way to turn it off via the wifi connection or whatever. That part's not that hard.

I'd suggest having a second battery with that setup too only because you don't wanna accidentally strand yourself or something.

**piabu** · 02-08-2006, 08:08 PM

You may wish to reconsider the proposition of needing the carPC at full power at all times?

Do you need it running certain background tasks? Or are you after an "instant-on" solution?

In the former (example: data logging of voltage, temperature sensors) you may wish to look at low-powered microcontrollers? Or maybe running the system in a partially-powered mode with LCDs and audio turned off to conserve power.

In the latter, consider the possiblity of remote turn-on solutions. Or on reducing the "power-on" time by tricks like S3 standby or timers to turn on your machine (if you have a fixed schedule).

Not to say that a fully-powered carPC on 24/7 is not possible, but it does present a formidable technical challenge in terms of power requirements.

**metwono** · 02-09-2006, 02:45 AM

I have been researching deep cycle batteries. As mentioned before, Optima is the way to go. They actually make a marine deep cycle battery that is designed for what your describing.

http://www.optimabatteries.com/publi...cal_specs.html

Looks like the D31M has the largest capacity(155 vs 110 for the red top). After looking up the price(200.00), I just couldn't justify it though. Especially when Cosco has the red tops for 90 bucks...

Also, that piticular batter has an odd shape to it. But, if you have the budget, and the room give it a try!