My sprinter motor home came with a solar panel and 2 batteries. I’ve never seen the charging light come on even on the sunniest days. My husband pulled one of the batteries and tested it and then the ...
Did DH realize the GC batteries are 6V and test correctly? ie Test as 6V or connect in series and test as 12V.
Marine deep cycle are just slightly better than starting batteries. GC batteries are generally much better for RV house batteries. He'll need a voltmeter to determine if the solar is charging.