Battery Isolator did not work

[Jack Wasmuth]

Left my interior lights on for three days and nights(did not know it) and my engine battery was dead. Guess my isolator did not work. Any reason why?

[postman]

Jack Wasmuth,  I noticed there are several types. If yours uses a hardwired ground separate from mounting, I would check continuity to frame. Check chassis battery's condition it may have died on its own. Lastly I have seen configurations of house batteries charged off altenator that would do this and others that wont.

I dont have enough info to draw a conclusion other than the obvious the isolator is bad.

[Jack Wasmuth]

New isolator, new battery. This is the old style solenoid type. Three wire. In out and energizer. 

[postman]

old style solenoid- again be certain you have a good ground were it is mounted. Follow that ground all the way back to the battery negative post clamp. Could be a waste of time, but I got more time than money! Then I'd focus on the (+) operation.

P.S. I have two. Someone added one...

[Jack Wasmuth]

Good ground. Other than the energizer to flow current to coach battery, what stops current from flowing back?

[Jack Wasmuth]

What I meant to say was what stops the coach battery from drawing on the engine battery?

[postman]

We can speculate till the cows come home. Nothing if the energizer is "on."

A bad cell would cause that till the batterys were dead.

My suggestion is collecting every schematic we both can. Way back in the day bad Alt. Vregs could kill batteries, but that could be tested almost anywhere auto.

[Jack Wasmuth]

Thanks for your input.

[Russell E Johnson]

There is a diode setup in the isolator that prevents power draw from the coach to drain the chassis battery. It has to be shorted. 

[postman]

While searching the archives I came across this thread. the subject is relavent, kinda.

https://goodoldrvs.ning.com/forum/topics/1988-southwind-house-batte...