Battery charging

[AndyIlles]

Hi again, all.

My '76 came with fairly new-appearing batteries for both the coach and engine.  There's a 10ga wire connecting the 2 batteries through what looks like a relay and some small rectangular box above the radiator. When on shore power, the coach battery stays charged, but the engine one doesn't, and goes dead in a few days.  Other RV'rs tell me the engine one should be charging off shore power too.  Any ideas why it's not?

Thanx again
Andy

[HPotter]

It's not supposed to. The relay (solenoid) connects the two batteries together when the ignition key is on, so both batteries are charged while travelling. When you shut off the engine the solenoid drops out and separates the two batteries, so if you run the coach battery dead while camping, you can still start the engine.
It sounds like you have some constant drain that is taking your front battery down. You need to remove one cable from the front battery and connect a low-range (like 1 amp.) ammeter between the cable clamp and the battery terminal. Any rea-ding on the meter is an unwanted drain, assuming everything is turned off, and then you have to go pulling fuses and disconnecting things to find the sneak path. The meter should read zero when you find and disconnect the leaking circuit. One such problem is a glove-box light that stays on when the door is closed. Good hunting!

Harold, ACOC 886

[AndyIlles]

Thanx, Potter.

You were right.  I isolated wire by wire from the battery, and sure enough, one has a constant drain, though I haven't been able to find exactly what it is yet.  Removing the fuses one by one hasn't produced a result yet, but I'll keep searching, no that you've put me on the right track.

Question. Is there a way to keep the engine battery also charged off shore power?