I have my Mac mini in my car and a P1900. Recently (about the last month) I have seen my car strain to start (like the battery was getting low). Now, my battery keeps constantly dying on me. What is up with the P1900? It hasn't been doing this before my GPS receiver install I think, and I don't know what's going on. My battery is the original, but on a 8000 mile car, so I don't think that's the problem.
Also, if something is draining little by little, will a new Optima battery help me out any?
Can anyone help me please?
Could you give us some insight as to how everything is wired?
I reckon your GPS is draining power even while your mac is in standby. Set it up so the secondary power output shuts off completely, if you can do this. Some USB devices often stay powered even when a system is in standby. Somehow set it up so your secondary power is killed when your computer is shutdown.