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TeamD_NC · 10-17-2018, 05:46 PM

2011 Winnebago 32k

Coming home from a recent trip I noticed a sulphur smell in my coach. After some investigation I found my 4 year old starting battery had boiled over and was too hot to touch. Put the multimeter on it and found it to be dead.

When I removed it from the battery box (not plugged into shore power and battery disconnect switch set to disconnect) I let the cables drop thinking they would be dead and to my surprise, the positive terminal arked on the battery box. I took a reading with the multimeter. The cables had the same reading as the house batteries. Experimenting further, I plugged into shore power and again the reading on the cable and house batteries was the same. I've since replaced the starting battery and in every situation (engine on, engine off, shore power, no shore power) the reading at the starting battery matches the house batteries exactly. When I start the coach, the house battery reading drops indicating the engine is pulling juice from them to start.

Seems like the house and chassis batteries should be wired separately, otherwise what is the purpose of the boost button at the dash. I'm wondering if there is a problem here which led to my battery frying.

I checked out the MOBAC using the tests spelled out on the manual and it worked like the manual stated it should, though I'm still not convinced there isn't a stuck solenoid in there.

Should the house and chassis battery always be wired together like mine are?

If not, where should I start my hunt?

Thanks.

twinboat · 10-17-2018, 06:30 PM

Start at the isolation/boost solenoid.

With engine off, shore power and generator off, and surface charge depleted, you should find that the boost/isolation solenoid is open.

There should be no power to the small, activation terminal, and one large terminal should only read the voltage of the chassis battery and the other large terminal should only read the house battery voltage.

Turn on some stuff to bring each battery bank down a bit to confirm they are not tied together.

Remember, if there is a charging source, the isolation solenoid may close, to charge all batteries. That's normal.

cbeierl · 10-17-2018, 07:15 PM

Here's the Battery Installation diagram for your coach. You also might find the Chassis Electrical Box Assembly diagram and the Chassis Wiring Installation diagram useful.

TeamD_NC · 10-19-2018, 11:10 AM

Thanks for the replies. My unit is equipped with a MOBAC 200 amp battery controller by Intllitec. The solenoids seem to be buried in that black box which states "no severcible parts inside" . There are 4 buttons on it that you push to test. When I push it, I can hear the solenoid snap and the led light comes on as per the trouble shooting guide in the manual. However, if I test the continuity between the chasis and house terminals at the box, it shows that the line is continuous. This leads me to believe the problem (if I have one) is inside that box. It's an expensive repair so I want to be sure.
Anybody with experience on these MOBAC boxes that could shed some light on how they behave?