I have a secondary battery that lost it's charge. While investigating I noticed that the Redarc battery isolator was behaving unexpectedly.

The isolator would briefly light up, then immediately turn off. The negative lead from the secondary battery, which leads directly from the negative terminal to the truck body, would jump each time. This process would repeat itself as you can see in the video. When the engine is turned off, this process continues for another minute or so. Any idea what the issue might be or how to diagnose it?

The primary battery has a charge just over 12.7 volts.



Thanks in advance for any suggestions!