Solar panels overcharging batteries

[Condo1]

Recently saw the Sun Explorer I panel flashing battery voltage of 16.7. Was on shore power. Disconnected shore power and couldn’t bring the voltage down running maximum battery operated items for 20 minutes. Unplugged panels on the roof and battery voltage went to 12.7. Any ideas. I’m suspecting the charge controller.

[richard5933]

Check to see if the solar charge controller is set to go into equalization mode from time to time. This sounds like an equalization voltage, and as you can guess it is not good to do while things are connected to the system.

I've got mine disabled and only do the equalization manually, and only after disconnecting all house systems.

[NC-Serenity]

I have a 2018 International with factory solar. The Airstream controller is not a great unit. Replace it with a Victron Solar Controller with bluetooth connectivity. It is a much better unit and will let you specify the bulk charging voltage and duration. If you have AGM's likely the battery spec's call for a higher voltage bulk charge then the factory controller delivers. My original controller kicked off at 12.7 volts. Lifeline actually calls for nearly 14v (depending on the battery temp). Best money I spent on the trailer by far...

[Condo1]

Hi, NC-Serenity. Thanks for the note. Where is the solar battery Charger controller located. Behind my sofa I can see the large DC control box. Inside?

[NC-Serenity]

In my 30’ international it is under the front couch mounted on the inside of the front wall of the trailer.

[uncle_bob]

Hi

I don't think the tried old Atkinson / whatever solar gizmo *has* an equalize mode. It certainly does not have much in the way of settings. This sounds more like an outright failure of some sort.

https://atkinsonelectronics.com/sune...-with-display/

They are now up to the III or 4 version and yes, they have various features. The stock install ones from a few years back ... not so much.

Bob