Laptop car PC, Power killing battery when on standby

**mcoutlawz** · 01-06-2009, 07:07 AM

Hi everyone,

I've just finished installing my car pc. I won't go into a lot of detail here because I plan to show off the finished product once I get through a few teething problems.

The problem I have at the moment is that because I'm using a laptop (in the boot), and I use "Wake on USB" to bring it out of standby when I enter the car, it keeps draining my battery as its constantly connected to the 12v cig lighter thats in the boot (mk4 Golf).

I did buy a power monitoring device from Maplins which supposedly only gives power to the laptop if the car battery is in good order.

But after testing it for a few days, woke up one morning to find a dead battery.

At the mo I'm plugging the power into the cig lighter every time I use the car (then removing afterwards).

So, I'm either looking for some hardware like the device I was using, or some software which can intelligently manage the power consumption of the laptop only giving it power when it needs (like if it gets to 25%, it charges until 60%).

I've spent an hour looking on the internet for some free software, but can't find anything suitable (naughty google!).

Anyone have any ideas? (I don't want to spend any more on this project if I can help it).

**WuNgUn** · 01-06-2009, 03:32 PM

So, your clearly using 'Sleep' or Standby...not a very good idea for carPC's, for this very reason...
If you MUST do it this way (hibernation highly recommended!), maybe you can add a solar panel to the setup? Or an intelligent PSU with better battery monitoring...

But obviously, you need to look at the root issues. Regardless whether or not the battery minder is working, your PC is clearly using too much current in Standby.

What will happen in the long term, is the battery minder will kill the power to your laptop to save the car battery, and then you have to do a FULL reboot of the PC because your standby data will be lost...

Best solution: Hibernation

**skuller** · 01-06-2009, 11:02 PM

simply add a relay to only give power to the laptop when the ignition is high.

Since you're using a laptop, I assume the battery is still working fine.
standby on laptop usually would last days if not weeks.