General Electrical Problem...questions about testing

[kazlx]

The diesel is my first vehicle with 2 batteries, so I want to make sure I'm not screwing up my readings and coming to the wrong conclusions.

I have been having a problem with the batteries dying. I think it is from the stereo (2 amps, 1 speaker, 1 sub amp, all 'professionally' installed). The weird thing is that the problem is recent and the stereo has been in for almost a year.

Do I need to isolate one battery to check for amp draw with a meter? The stereo is fed from the driver (aux) battery with 1/0 cable through a 150A fuse to a distribution block to 4ga to each amp. Disconnecting the main amplifier cable and inserting the meter, I get about a 1.6A draw with the truck completely off and the key out. This seems wrong to me.

I took it to the stereo shop and they told me it isn't the stereo. He told me they checked the stereo with one battery disconnected and it is fine, but I am getting a draw somewhere that stops when they pull fuse 22 in the hood box (a 50A maxi) that the owners manual says is the junction box fuse. I am guessing this is the main battery feed to the junction box, so that doesn't really isolate anything.

I am pulling my hair out because I don't trust driving the truck anywhere.

I guess my main question is do I need to isolate one battery to test amp draw by pulling fuses?

[sea-level]

Your first step is to see if the amps are on when the key is off. If they aren't, more than likely it is not the system. UNLESS, you have a capacitor, I have seen those drain some batteries before. To eliminate the system, disconnect your power line that goes back to the sytem and let it ride for a couple of days. It will suck not having a radio but if your battery does not drain with the system disconnected then you know that the system is not the problem. Who installed it?

[sea-level]

Oh, isolating the battery is not going to solve anything either. You might isolate the problem but eventually it will get worse and you will start killing off one of your batteries every month.

[kazlx]

By isolating the battery, I meant just while testing, not as a fix. If I remember my physics correctly, the batteries are wired in parallel, which shouldn't affect the current draw. The amps are not on (well the power lights arent lit), but it would seem that the system shouldn't be drawing almost 2A with the truck completely off. I guess I can just unplug the system and check that way, but I just hate having the batteries die and having to charge them...