Battery Isolator Not Working

Hi CA Traveler,

I use a 2500 watt inverter and want an even larger one. A 500 amp surge is within the parameters of my system while using the inverter. I understand why he wants to measure--but if his inverter is as large or larger than mine my personal view is that I would not want the shunt involved.

pianotuna wrote:
I would not put my inverter through a shunt. Too much chance of a surge taking out the shunt and leaving me without cabin power.

What's behind this statement?

That would mean that the battery monitor is unaware of the inverter draw.

If I was to get a surge that takes out my 500A shunt then most likely there would more important considerations than my shunt which could be easily bypassed.

Hi CA Traveler,

Good advice on the negative cable disconnect!

If you have power on the purple wire the solenoid should engage. Then if you have charging voltage on the chassis battery side and not on the house battery then replace the solenoid.

Pianotuna's diagnostic procedure is right on the money...

I h-a-t-e those solenoid type isolators. I much prefer the Essex type bi-directional "smart" solenoid. They can rate the can solenoid for a billion amps but they'll only carry 60. I even tried the 11880 solenoid with silver contacts years ago and they too were junk.

Someone else will chip in about the smart solenoids. Again I love the new stuff. They protect themselves and do not need an ignition signal wire to work.

Is the chassis battery being charged from the alternator? If so check the wiring against the pictures that you hopefully took before the new batteries. The n check the two small control terminals (if it's a solenoid) on the isolator.

Once you got the sparks then the isolator or something else could have been zapped.

BTW There are several good reasons to disconnect the negative battery cable first and connect it back last. Prevents those sparks is one reason.

Hey there Mex, here's a pic of it. It's a Camdec 97226-wr.

Hi pNuker,

If it is a relay that is energized when the key is on have someone else turn on the key while you listen for a "clunk". If you hear the clunk then check for power on both "sides" of the relay. If there is no clunk check to see that the small wire has power when the key is on. Mine had a fuse before the relay that I've caused to be replaced by auto reset circuit breakers.

Relay type isolators do fail and contacts do burn. My Ford OEM one lasted less than a year, in spite of it being rated for 100 amps. The contacts were in poor shape. The "intelligent" design folks put the relay down below the starter battery so the battery has to be removed to service or check the relay. Of course you can't check it with no starter battery. The one I used to replace it is a lot better made.

I would not put my inverter through a shunt. Too much chance of a surge taking out the shunt and leaving me without cabin power. I would have a heavy duty manual switch on the inverter as well.

Isolators come in different flavors. What does yours look like?