Thor Forums

[Oneilkeys]

Originally Posted by rvschneider

Hi all. New to the forum. I've been trying to educate myself on the RV electrical system. This is thread is great, but I still have questions. Problem: My chassis battery was dead the other day, even though I had it plugged in to shore power; Use switch was ON. (Coach battery was fine)

So today I went to the RV and located the Isolator relay under the hood. Took some voltage readings in an attempt to isolate the problem (no pun intended ). Sorry for the long post but here's everything I measured:

1. Engine OFF. Not Plugged in to shore power. 'Use' switch ON. House battery 13.0V. Truck battery 13.0V. Isolator relay not engaged. This is just my baseline so yes I know this step is unnecessary.

2. Engine OFF. Not Plugged in to shore power. Use switch OFF. House battery 13.2v. Truck battery 13.0v . Isolator relay not engaged.

3. Engine OFF. Plugged in to shore power. Use switch ON. House battery 14.0v. Truck battery 13.0v. Isolator relay not engaged.

4. Engine OFF. Plugged in to shore power. Use switch OFF. House battery 13.0v Truck battery 13.0v. Isolator relay not engaged.

---- Started the engine----

5. Engine Running. Not plugged in to shore power. Use switch ON. House battery 15.0v. Truck battery 15.0v. Isolator relay engaged (energized and equal readings on both large posts).

6. Engine Running. Not plugged in to shore power. Use switch OFF. House battery 15.0 . Truck battery 15.0V. Isolator relay engaged

7. Engine Running. Plugged in to shore power. Use switch ON. House battery 15.0V. Truck battery 15.0V. Isolator relay engaged

8. Engine Running. Plugged in to shore power. Use switch OFF. House battery 15.0V. Truck battery 15.0V. Isolator relay engaged

-----

Since the Isolator relay actually does function and allows charging from Chassis --> Coach (but not the other direction) my guess is this is a bad BIRD?

Thanks!
_______________________
2014 Thor Four Winds 32'

Everything seems to be working correctly while under engine power and the Trombetta (pic #1) is opening and closing correctly while the engine is running. Everything on the coach side seems to be working as it should except for #3 where the Trombetta is not opening when the coach is on shore power or generator. Since everything else seems to be working correctly and the Trombetta is working while the engine is running, the problem probably is with the BIRD or BCC. If you have a BIRD, it says BIRD on it and there are four wires coming off it. That red wire coming off the Trombetta in pic #1 that has a fuse holder attached to it should lead back to the BIRD. In my coach the red wire from the BIRD is hooked to the coach batteries. If u back up a take a wider view picture, I might be able to see the BIRD and the wires. Have you checked the fuse holders attached to the wires that run from the Trombetta? If the 5amp fuse is blown, the BIRD cannot sense the voltage at the coach batteries, so it will not open the Trombetta to recharge the chassis battery.