P Chassis battery drain

[ebg338]

I have a 92 Winnebago Adventurer on a P Chassis. Got back from our trip to Orlando and parked (ran / started perfectly). Got up the next day and the chassis battery was very drained, wouldn't start, just some clicking. Checked everything I could think of and recharged the battery. Started right up. Next day, same thing. Battery drained overnight. Removed battery and installed new one. Started right away. Next day, you guessed it, battery drained.

Looking for any info on steps to walk through to isolate what's is draining the battery. I've checked every switch and anything I could think of related to the chassis.

Recommendations are appreciated.

Thanks,
Bill G

[tomwalt]

Here's an easy check - Just last fall I had the same issue with my 1992 Caddi - upon walking by the rear I noticed the brake lights were on dim (it was hard to see in direct sunlight. I found the brake light switch contacts had a build up that was causing this (I'm guessing it was from the extra current from towing a TT). New switch was only about $10, but you can open the old switch and clean the contacts easily if it is the same. The switch was licated under the dash - driver's side.

[HD4Mark]

This happened to us. Ours is a Freightliner chassis so it may not apply though. We were connected to 50A shore power for only a day. Next morning no start. Jumped it and everything was fine. The only two things we found to cause it was 1. the inverter was set to on and 2. one wing nut on the house batteries was loose. Neither one makes sense since the inverter runs off the house batteries and AFAIK should not draw on the chassis batteries. However from then on we make sure all the connections are tight and check to see the inverter is off unless needed and (knock wood) has not happened again.

[depchief]

check to see if you have inadvertently turned on your mirror heaters

[ebg338]

Update...

So I recharged the new battery (reads 12.52 V, with rv running it reads 14.6) and connected the positive. Used a meter to measure the neg post to the neg cable and detected a .1 amp draw. Started pulling fuses and it turns out it's the radio. Is a .1 draw enough to drain a battery overnight?

I'm going to let the RV run for a while and guess my test will be to let it sit overnight and try starting it in the morning.

Additional thoughts appreciated and thanks for the responses I've already gotten.

Bill G

[M&EM]

Depending on when you made the measurement, 12.52V may not be very well charged. Still, .1 amp over night discharge rate is only 1.2 Ahrs and should not be noticed when starting in the am.

Marty

[Max Hubrich]

I guess the easiest way to find out if the radio is doing it- leave the radio fuse out, charge the battery and wait and see-.

Let us know,

Good luck,

[jhalldiver]

Ok Now I am confused, Should I turn my Inverter off when I am connected to Shore Power. My starting batteries are draining. I replaced both batteries and I am considering installing a battery disconnect on them. I can not find anything on that would drain them Help

[mgscott4]

You could have a bad battery. One bad cell could drain the battery overnite. Get one of those specific gravity testers with the floating balls in the glass tube and test the elctrolyte in each cell when the battery has a full charge, each cell should be identical.