I think it's time for some pictures of the wiring and connections. There is high resistance or this would not be happening. In a parallel circuit the voltages will be the same unless there is some resistance in series (in a run of wire). I am curious. If you unhook your amp, do the batteries read the same voltage then? If so, then connect the amp again but unhook the remote lead. Now are the batteries the same? If they are still the same, you need to have someone with a DC clamp meter, see what your amp is drawing with no music. If it's drawing greater than an amp or two when not playing anything it needs to be repaired.
Do you mean with the car running or off? Running I assume? Unfortunately, I don't know anyone with a clamp meter, so let's go through the first couple of steps first...
car running, yes. i think you can do what he's saying by pulling the remote and checking. if the same numbers, then re-connect the remote. if that doesnt make a difference, then get the amp checked. testing for a bad amp...
that resistance might be the length of the wire. it's not much. the resistance you're worried about is between the amp and the rear battery. or maybe internally in the amp. how big is your alt? that should be closer to 14.4v w/ the car running.
This shows the amp is good, the wire has high resistance somewhere. This happened to one of my dad's hi performance CB installs. He was a die hard solderer until we had this same problem. We replaced it all with crimp ons and it fixed it. That SHOULDN'T happen, but sometimes it does.
Testing with car on, HU on, HU volume at 0, remote hooked up:
Honestly, I didn't know the first thing about soldering, I just started doing it on all my lugs one day. I didn't know what a cold solder joint was or what causes it until you mentioned it in this thread. After having learned a thing or two I'm sure that my technique has improved, and I should resolder these terminals.
