Advice about power

**atiti** · 01-15-2011, 09:41 AM

Hi Guys,

I'm studying to be a computer scientist and I'm also interested in cars. I bought my second car just a few months ago, a little Mitsubishi Colt CZ3, and I've been entertaining an idea of building some cool vision system for detecting lanes, other cars/license plates and road signs.

So I built in a webcam, got myself an OMAP3 based embedded board, and set it up in the car. This part of the setup works pretty well, I still need some of the vision algorithms tho...

I've also been thinking about turning this into an alarm system, but that would require it to be running all the time. Now as far as I'm aware, the power consumption of the electronics are around 250mA on average, with a peak of 1A @ 5V. For this I've been using an off the shelf DC-DC converter, but I was wondering if you guys think it would drain the battery too much?

I plan on having an off switch for when the car isn't used.

**soundman98** · 01-15-2011, 10:49 AM

alarm systems are going to be much lower draw, and less temper-mental..

a typical car should see a parasitic load at the battery of less then 0.5A. anything over that is considered high draw.

if you are really interested in keeping the pc on all the time, it would be in your best interest to use a second, dedicated battery for this, so that you will not kill your main starting battery, and be stranded somewhere. many of OldSpark's posts have info on how to power/charge a secondary battery, and there is also some info in tripzeros "[insert name of project] worklog" that details this..

**tripzero** · 01-15-2011, 12:14 PM

what omap3 board are you using?

I've gotten my igepv2 to run 5 days before the battery drops below what would be required to start the car.

**soundman98** · 01-15-2011, 12:29 PM

Originally Posted by tripzero

what omap3 board are you using?

I've gotten my igepv2 to run 5 days before the battery drops below what would be required to start the car.

just remember-- if it were connected to the main battery, you would have to add the carpc load to the parasitic load of the cars systems-- usually car systems are around 0.2-0.5A draw(my brother just measured a 09 jeep, and it was 0.3A), so once you step above 0.5A parasitic draw, your battery will go dead much faster..