Battery Isolator Question

[Wandering Sagebrush]

My Cougar doesn’t have a charger, just solar and the truck when plugged in. A few weeks ago I noticed the batteries were a little low, so I plugged a charger in and brought it up. Yesterday, when I went out to get it ready for camping season, I noticed they were even lower than the first time. So I charged again… and as I was closing up, I noticed the red light on the isolator was on. I removed the camper ground from the batteries, and the relay clicked off.

I don’t have a schematic, so don’t have a good idea why it’s triggering with a charge going direct to the batts. Could any of the electrical geniuses educate me?

 

[Jon R]

I don’t know about being a genius, but I’ll offer this:

You didn’t say which isolator you have, so I will talk about the Blue Sea ACR that came with my 2021 Grandby. If it detects voltage above 13.0 for two minutes on either positive, the relay connects the two positives. It will connect in 30 seconds if it senses 13.6 volts on one positive. If the voltage drops to 12.75 volts, the relay will disconnect the two positives.

Connecting a charger to either battery will cause the ACR to connect the batteries once the charging voltage exceeds 13.0 volts. That might explain why the isolator was closed while you were charging, but doesn’t explain why your battery was discharging.

The Blue Sea ACR draws about 175 mA when closed (relay coil on, connecting the batteries) and about 15 mA when open. You should be able to do an internet search to fine the specs of your device.

 

[Wandering Sagebrush]

Jon, thank you!

 

[Vic Harder]

Were you still charging at the time? At the truck battery or the camper battery? Removing the ground would turn off the isolator.

 

[Vic Harder]

oops, didn;t see Jon's reply. You good now WS?

 

[Wandering Sagebrush]

Vic, I believe all is well. Resting voltage is a bit over 12.7 VDC. I’ve reconnected the ground. The Coug should be on the truck tomorrow.