"Main" (Chassis) battery switch doesn't work unless I charge via plugged in

Only had the coach about a month and figuring out small issues. I noticed if it's been sitting a week or so without plugging in to charge the batteries that the rocker switch for the Main batteries wont turn on. It will turn off fine. The Aux switch works fine both ways.  If I put the ignition key in and and just turn once, the main battery light will go on. The main switch won't work most of the time even after driving around and having the genset on for a few hours at the end of the day. I thought something was wrong with the switch until I plugged the RV in over night to make sure all the batteries were well charged for a drive the next day. The next morning when I didn't have it plugged into the house, I noticed the Main battery switch was working fine after it had been charging all night. The  Aux batteries do seem to drain quickly but I'm still able to start up the Gen set if it's been a few days. The GenSet didn't' want to start once after it have been sitting a bit but the main batteries started up the engine and I was able to start up the Genset withing 30 seconds of starting up the Genset. I realize that something is draining the Aux batteries quicker than it should but the Main batteries have stayed charged. It just seems odd the that Main switch worked fine after an overnight charge even though both the house and main batteries seem to have an adequate charge the day before when it wasn't working. It's almost like just 1 of the batteries that is used on the Main battery switch is staying completely dead and wasn't getting charged while the engine or Genset were running  during the day. It only got charged when it was plugged into my house power. Any ideas or something else like a small battery in the battery control box?

You have an intermittent problem with the switch or the switch wiring.  The fact that the main battery disconnect comes ON with the ignition switch, says the disconnect solenoid (relay) is working fine.  There is a circuit in the BCC that makes this happen.  It is designed that way so that you won't lose power if someone accidentally turns the main switch OFF while driving.

You do need to check the condition of your aux batteries.  They are probably going bad.

Is this a 3 position Rocker  (ON)normal(OFF)  (the prens means the switch returns to center when you are not pushing it)

If so let me tell you the story of a man name John (From Detroit) and the AUX batteries on his RV.

had exactly the same problem.. OFF (Store) Worked great  ON (Use) not so well (or at all)

Removed power from the switch (Easiest way is to, without shore power, remove NEGATIVE leads from ALL batteries) House and Chassis,  Or in some cases you can simply disconnect the switch from the wiring harness.. at least the center lead if you can do just one lead..

now cycle the switch many many times, I'd go with at least fifty.

Then re-connect and try again.. IN my case that did it.

Problem: Dirty stitch, corrosing (Tarnish) set in while it was waiting on an RV to live in,, Failure to operate allowed Tarnish to build to the point where it could nlt self-clean fast enough..  Repeated operation WITHOUT any Voltage or current allowed it to self clean and operate.. Since I went well beyond enough to just make it work it has continued to work.. Though in truth I may have an issue next time I try it (Due to non-op due to flown engine)  Since I now know which fuse feeds it.. I will pull fuse.. then cycle many times,, should that happen.

Thanks John. I had read you post earlier about the self cleaning tip. Our switches stay in a neutral position all the time and you toggle it on off and it goes back to neutral.  I thought about your post as a possible solution but when I figured out it was related to how well the batteries were charged, it led me to think it's something else. It could be Lou's suggestion of the Aux batteries going bad but the GenSet is starting fine and the Aux switch doesn't have the same issue. I'll do some more investigating/testing of batteries and power. Something that I think is odd when I'm driving or probably just running but I notice it when I'm driving is it sounds like I hear relay clicking or some electrical changes under the dash in front of me. It's a hot mess of all the electrical wires under the dash so obviously not something you can easily figure out. I don't think I have been under the dash looking around with the engine at idle which I will need to do also. I suppose it could just be a bad ground or something that else that could be more serious. I have put about 250 miles on it since we bought it and the only other electrical issue I see is the blinkers flashing fast. I have confirmed all the lights work so I try a large flasher as some have suggested here.

How do you determine that the main battery disconnect is NOT working properly?  What exactly are the symptoms?  What doesn't work when you think the batteries did not turn ON?

If the main battery did NOT connect, (either through the switch -or- via the ignition switch ON) you wouldn't be able to start the engine.  You have not said that starting was a problem.

Am I misstating the symptoms?

Lou, sorry for not responding right away. The engine batteries seems to work fine with the ignition and have always had enough charge to start the engine.  The main symptoms are:
1. Main switch on the control panel wont turn on. (e.g. Doesn't light up when I hit the on toggle even if I try a few times). The Aux switch works fine at that time. As soon as I attempt to start the engine, it then turns on/lights up.
2. I have noticed the chassis batteries drain faster than I would expect even when I have both the main and Aux switches turned off. There has been a couple times that the Aux batteries didn't have enough juice to start up the GenSet and I had to start up the Engine battery and I pressed the Combiner button to get the GenSet to turn over and start.
3. I also have heard clicking like relays or something electrical under the dash while driving that I haven't pinpointed yet. I need to look into this some more when I have time.

GarrettG said:

Lou, sorry for not responding right away. The engine batteries seems to work fine with the ignition and have always had enough charge to start the engine.  The main symptoms are:
1. Main switch on the control panel wont turn on. (e.g. Doesn't light up when I hit the on toggle even if I try a few times). The Aux switch works fine at that time.

Click to expand...

This sounds like a faulty switch or a loose or faulty connection in the switch wiring.  Check all

As soon as I attempt to start the engine, it then turns on/lights up.

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This is NORMAL operation in RV-CP BCC's made after 2003.  It's called the Electronic Disconnect Driver.  It overrides the switch setting, and is shown in Figure-2 of this linked document.

2. I have noticed the chassis batteries drain faster than I would expect even when I have both the main and Aux switches turned off. There has been a couple times that the Aux batteries didn't have enough juice to start up the GenSet and I had to start up the Engine battery and I pressed the Combiner button to get the GenSet to turn over and start.
3. I also have heard clicking like relays or something electrical under the dash while driving that I haven't pinpointed yet. I need to look into this some more when I have time.

Click to expand...

The two items (2. and 3.) sound like the result of weak and failing batteries.  The clicking is most likely the result of the chassis battery voltage dropping low enough to cause the Isolator relay to drop out and then recconect.  You may have an alternator going bad, or another loose or faulty connection problem.  The solenoid, itself may be failing under heat of continuous operation.

Thanks Lou. The alternator going bad or a bad connection to the alternator is something I should consider. Thanks. I probably wont get to trouble shoot until next week. I'll be gone most of this weekend. I'll keep you posted.