Engine alternator only charges engine battery

It was such a good feeling to FINALLY solve this issue. Now we can use our inverter while driving for small items like laptop computer, etc without having to turn on the generator or having to be concerned with a dead battery. Great to have this working!!

Just saw your latest post. Congratulations, and thanks for providing feedback on the blown fuse. I may need to know that someday.

Here's how I understand your test results....

With the ignition off, you should see house battery voltage at one terminal on the boost switch. This terminal connects to the house battery. There should be no voltage at either of the other terminals.

With the boost switch pressed, a second terminal shows voltage. This is the wire that provides voltage to the center terminal on the solenoid.

The third terminal connects to a wire that must come from the ignition switch. If no voltage is on this terminal when the ignition is on, there is an issue with the ignition switch. I'm guessing here, but it is also possible that the ignition switch activates a relay that provides chassis battery voltage to the third terminal. This relay, if there is one, may have failed.

Winnebago customer service should be able to provide you with details of the circuit between the ignition switch and the third terminal.

Final update: Problem solved. The problem was a FUSE (15amp) on the fusebox next to the steering wheel. Fuse was for heater/blower which this wire is tied to. According to the drawings, it is supposed to be this way. Replaced blown fuse and problem solved. coach batteries being charged while engine is running.
Thank you all again!

Update: No voltage at the center post yellow wire when engine is running.

No voltage at the battery boost wire that should be hot when the engine is running. bottom wire hot, middle hot when button pushed, top wire no hot. this is the wire that is supposed to run to the center post of the battery solenoid.

If the new solenoid looks like the one in my picture on the previous page, the small wire to the center terminal is supposed to have voltage (from the chassis battery) when the ignition is on. Not necessary to start the engine, just turn the ignition on and check for chassis battery voltage at that terminal. No voltage means that there is a problem with the circuit between the ignition switch and the center terminal.

It is my understanding that the Boost switch on the dash is there so that the engine can be started from the house batteries if the chassis battery is dead. When the Boost switch is pressed, it sends voltage from the house batteries to activate the solenoid. If you have someone hold the Boost switch, you should find the house battery voltage at the center terminal, as you say that the Boost switch does work.

I'm not sure of this, but I seem to remember being told that the boost switch is a double pole switch with three wires, one from the house battery, one from the ignition switch (chassis battery voltage when the ignition switch is on) and the third going to the center terminal on the solenoid. The Boost switch is spring loaded so that the circuit between the ignition switch and the solenoid is normally connected. If this is correct (check with Winnebago) then your problem could be with the Boost switch or the wiring between the ignition switch and the boost switch.

I have found Winnebago customer service to be very helpful. (800) 537-1885

MrWizard wrote:
well the NEW relay is either NOT connected to the RV batteries
or
it is not being powered on from the "ignition" circuit when the engine is running and it is supposed to be powered on

Maybe it is connected incorrectly. I reconnected the new battery mode solenoid exactly like the old one. It will charge the battery if I hold down the "Boost" Button on the dash.

One cable from the chassis battery

The other cable from the house battery

A tiny ground wire

And it works both directions AUTOMATICALLY. Everything stays charged. No switch. No rat's nest of wires. No hyper-doses of Ginko Biloba needed to help the memory to remember to flip switches.

And some folks wet their jeans fretting about taking three seconds to look at a meter as they walk by.

well the NEW relay is either NOT connected to the RV batteries
or
it is not being powered on from the "ignition" circuit when the engine is running and it is supposed to be powered on

And you wonder why I recommend the Sure Power Bi-Directional solenoid?