Battery Isolator

[T-man]

I have a 93 B-190 with the coach and engine battery under the hood. My batteries discharge if left for more than ten days without running or the shore power plugged in. Both batteries are Interstate, and both are less than a year old.

Is there a battery isolator in this vehicle? If so, is it the module behind the engine battery up on the firewall, the one with two posts and three positive cables connected to it? How can I determine if it is working? I am tired of replacing batteries and worse, running out of 12V power when not plugged in. My mechanic could not find a short except for an intermitant drop in power when I left it with him for a couple of days. I have a new solid state charger inverter in place. Any suggestions other than disconnecting the ground cables when I am not using the vehicle. I live in Taos, NM and it's a long way from any kind of RV dealership.

[skater]

The item you describe does sound like the isolator.

Here's what I'd suggest: either use a multimeter or get a clamp-on ammeter to see how much power is being drawn while the camper isn't being used (obviously it should be unplugged, with the engine off). Perhaps you have some parasitic draw that's running it down. You may have to do some detective work, like pulling fuses and checking each circuit individually.