The next day I set out to map some of the roads and tracks around a patch of Bush that I have been frequenting for a few years - recording native Orchid growth etc.

Here is the voltage recordings of the battery:

11:30 13.25V (No load)

11:32 12.63V (PC On)

14:45 strong electrical burning smell noted!

14:50 9.8V (No Load)

Ok, time to go for a walk and a drive...

I checked out my last lot of GPS code from the SWASC subversion repository and uploaded it to the MARK I mini-ITX PC. I then went for a walk around the park at the back of the house. The PC and GPS where running from a common 12V 7A Sealed Lead Acid (SLA), battery. The first walk lasted 1 hour 40 minutes. I noted the voltage drop over this period:

13:40 12.28V (on load)

14:00 12.14V

14:40 11.96V

15:00 11.88V

15:05 12.00V (no load)