Chattering Battery Isolater

[MrBob]

A friend asked me to take a look at her Chinook Concourse. The battery isolator, or separator, spontaneously chatters for about 5 to 10 seconds at a time. I can seem to connect it to any external event or time. We replaced that component with the identical unit and for a time the chattering stopped but now has returned.
The house batteries are nearly new. I cleaned the battery contacts on both coach and starter batteries. Alternator output is good, start battery measures 12.1 volts resting. The owner tells me there is a solar charger on the roof but she doesn't know anything about it, nor does she know where any switches for it might be located.
I doubt this is a new or obscure problem, and any suggestions are appreciated.

[caconcourse]

At least one person found that his isolator "clicking" stopped when he disconnected the solar input, which can probably confuse the switch with irregular charging/solar voltage. The solar connects to the positive house battery post by a small wire with an in-line fuse near the battery. You can disconnect it by removing the fuse. There is also a fuse on the stock solar controller high on the wall behind the passenger seat, if that is still installed.

This is not a normal situation, since most of the time, the isolator works fine with the solar. The stock solar controller does a very poor job even charging the batteries, as the technology was pretty new at the time. If the stock solar controller (Specialty Concepts Mark 15) is still installed, I would change it out with a new PWM controller no matter what. I have a Coleman 30amp PWM controller that fits the opening that has greatly improved my solar performance, even when I just had the single OEM 50W panel: https://www.amazon.com/gp/product/B004R ... UTF8&psc=1

[chin_k]

Is the start battery connected? If the Surepower separator is not connected to the start battery (I disconnect mine to make sure it does not get drained when I am not using my rig), the solar panel will increase the voltage of the coach batteries, and cause the separator to engage. Since engagement of the separator cause it to heat up and use up the energy in the batteries, it will cause the voltage to drop, and cause it disengage. This causes the chatter.

If the start battery and coach batteries are all connected, and it still chatters, then let us know, and we can look more into this.

[MrBob]

Thanks much for the replies. I've forwarded both of them to the RV owner.