Solar controller whine

[L&Twny]

Hello all,
My wife and I traveled to Tennessee from western NY Memorial Day weekend to buy our first camper, a 2015 2417 KS Silver Trail. Our lives have been very busy with no time to use it yet, but it has a structural issue at the right front lift arm bracket that I will have to deal with first anyway. My concern right now is getting it stored for the winter. As soon as I disconnected the battery ground cable, I heard a low whine from the vicinity of the 30 amp PWM solar controller. The Interstate SRM-24 battery was not staying charged after disconnecting shore power, and may not be good. I don't know which solar panel I have, and know nothing about them. Looking at it from the top, it is 4x8 squares in the panel. Am I correct that the controller is trying to charge, but nothing is connected? I would think there should be a way to disconnect solar. Does anyone know the cause of this sound, and what I can do about it.
This is a wonderful forum, and what a wealth of information!

[BrucePerens]

It sounds like an inductor in that controller doesn't like to work without a load. Better controllers sense when the battery is disconnected and shut down. If you don't want to mess with the wires, tie a tarp over the solar panel. If you're keeping the battery outside or in a garage that gets to freezing temperature, it needs to be fully charged and on a battery maintainer. Charged batteries have a much lower freezing point than uncharged ones. And lead acid batteries have a longer lifetime when kept charged in any case.

[L&Twny]

Thanks for the reply, Bruce. That is pretty much what I had thought. Is there a way to know which solar panel I have, and does anyone install a way to disconnect it?