I have a 2006 37U Fleetwood Bounder with the cat diesel. I have the F73-1042 REV M Battery Control Center. While on shorepower only house batteries charge and while engine is running only auxillary batteries charge. Aux start switch on dash does nothing. It has the 200amp Big Boy Battery Isolator. My question is what controls the Big Boy on this year Fleetwoods? Some mention a "BIRD" box (Bi-directional Isolator relay delay) which I have no idea where to find this or is it controlled by the circuit board in the BCC? I put a new Big Boy on and still the same problems. TIA for any guidance

I believe in 2006 this is how they worked. To charge the chassis batteries while plugged in you need a Trikl-Start which charges the chassis batteries off the house batteries while plugged in.

"engine is running only auxiliary batteries charge"You need to diagnose and repair this. Both chassis and house banks should be charged by the alternator with the engine running.

Check the fuse that controls the aux start/ charge relay. Mine is fuse 9 in the battery control center.

enblethen wrote:Check the fuse that controls the aux start/ charge relay. Mine is fuse 9 in the battery control center.Fuses all check out ok. Problem is deeper. Are the chassis and coach battery disconnects behind the BCC board just for the battery disconnects?

Just so you know AUXILIARY batteries ARE the house batteries. The Chassis battery is the "Main" at least on most RV's.

Fleetwood Motorhome Owners ... Help!!! | Good Sam Community

RLS7201
Explorer II
Dec 19, 2019
jaycocamper62301 wrote:
RLS7201 wrote:
Your system is set up from the factory to charge all batteries from all sources. You do not have a BIRD or do you need additional devices.
Most Non-Fleetwood owners do not understand your system.

Your 200 amp isolator relay is not functioning. Seeing how the relay is not functioning from the circuit board, in your BCC, or the emergency start button. I would guess the relay is bad.
Or you could have a bad connection on the control wires to the isolator relay. Look at the wiring print on the inside of the BCC (Battery Control Center) cover. It's really pretty simple.

Richard

Are the relays built into the board in the BCC because there is just a coach battery disconnect and a Chassis battery disconnect and 2 circuit breakers behind the control board?

The isolator relay on your coach will be close to the battery banks. One each large cable from each battery bank and two small control wires. It is larger that the 100 amp silver relay in a previous post.

Richard
avidude
Explorer
Jan 04, 2020
I have a 2007 Bounder diesel 38S. Same chassis as yours. I had the same problem a few years ago. Problem with the isolator solenoid/relay. Simple and cheap to replace.

enblethen wrote:
No, the relays are not on the circuit board. My relay looks like a Ford starter relay. Many people call the relays "solenoids". Mine are silver cans about 1.5 inches diameter and two inches tall. The Big Boy relays are black and a little taller. Two large posts and two small posts for the control wires.
Big boy
Battery switch Mine has two control wire posts.

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