boschat

This is not the case Linda S because if I remove the wire coming from the isolator from the house battery it reads 15.5 V. When I reconnect it to the battery it reads 12.8 V. The wire is not grounding out anywhere. Does anyone know, is there a regulator somewhere along the way from the isolator to the battery that somehow senses that the battery is fully charged and stops the isolator from sending a charge (full charge for most deep cells results in a 12.8 V reading)? I guess one experiment I could run would be to partially discharge the battery down to say 12.3 V and then see if the voltage would increase at that point upon starting the engine.

I just bought a 90 amp solid state isolator (its a NOCO IGD 90 amp 4 terminal solid state isolator) at the RV store that is similar to the one suggested in the link above along with a new 30 amp breaker. Interestingly, in the installation manual under the "Electrical Tests" section it says that house battery terminal should read between 14.8-15.5 V and the truck battery should read between 13.8-14.5 V when the engine is on. I just finished installing it and it does the same exact thing as the old one. So what the heck is going on when I connect the house battery wire from the isolator (which reads 15.5 V when not connected) to the battery (dropping the voltage to 12.8 V)?! I have no idea what to do at this point.

Completely bizarre. Makes no sense to me either. Clearly a switch can't increase the potential...I don't know what's going on with the thing. OK, I'll pick up one of those 4 terminal solid state isolators and a new 30 amp circuit breaker and hopefully that will solve the problem. PS: the #10 terminal on the isolator is for the ignition wire yeah cause I know that Toyota alternators need a feedback or something to that effect?

The truck battery reads 14.5 V when the house battery is disconnected. The house battery is brand new so I know its good. Do you know what solid state isolator I would need>

I have a 1989 Toyota Odyssey RV with a V6 in it. The battery isolator is a 4 terminal solid state type and puts out 15.5 V to the house battery wire when not connected to the battery, but as soon as I connect the wire from the isolator to the battery the voltage drops to 12.33 V (i.e., the voltage of the house battery itself). As a note, the wire that runs to the house battery 1st goes through a 30 amp breaker. 1) What the heck is going on with the isolator when I hook it up to the house battery?! The truck battery charges just fine when the engine is running, reading 14.5 V at the battery terminals. 2) Assuming I need a new isolator, what model do I buy, I can't find anything similar on the net and all of the lettering is gone off the one in the engine compartment.