Forum Discussion

BFL13's avatar
BFL13
Explorer II
Feb 09, 2018

Solar Float and Shore Power Float?

Been a few threads on this, but I never had the "issue" until now, so I am not too clear on just what is at stake here.

On shore power Floating the batts at 13.8 (or whatever temp comp adjustment calls for) you get a steady "correct" voltage.

With solar only, no shore power, you Float the batts by letting the controller do its "profile" during the day and it quits at night. With any luck, you will average out a "correct" Float in the 24 hours for the batts to survive.

BUT as I have now discovered for myself (despite those other threads on this :( ), if you have both shore power and solar, then during the day, instead of being at 13.8 (say) steady, the solar puts you up into the 14s, and at night, instead of dropping right down, the shore power keeps the converter going at its 13.8 (say), so your 24 hour average is higher than it was when just on shore power.

So it looks like the answer, if you are on shore power and solar, is to disconnect the array from the controller (leaving the controller on the battery bank), and just stick with the shore power and converter's Float.

Yes?
  • Pick up a book about the local area history and ignore batteries and voltage.
    Play a game with the the kids.
    Get a telescope.
    Walk to the lake.
    Ask the ranger for other interesting sights.
  • pianotuna wrote:
    Hi BFL13,

    Set the solar to the same float as the shore power. If the controller can't do that--then it is inadequate.

    Honestly I don't think 0.2 volts is going to "kill" a wet cell battery. It might gas a smidgen more.

    You could just float with solar only, too. I had no choice but to do that between 2009 and 2013.


    Agree...I like a little more push when solar only, don't notice excess water usage.

    600watts/flat mount/8 T105s
  • Are you saying "Never put an Armenian and a Greek in the same set of bunk beds?"

    When the batteries are charged, they are floated. The batteries call the shots not the chargers. On a permanent power pedestal, boinking the batteries once a month with the solar is a good idea.
  • Why if connected to shore power would you leave your solar system running? On the other side, I trust my solar system. I don’t trust shore power...RV park, my home, anywhere.
  • Hi BFL13,

    Set the solar to the same float as the shore power. If the controller can't do that--then it is inadequate.

    Honestly I don't think 0.2 volts is going to "kill" a wet cell battery. It might gas a smidgen more.

    You could just float with solar only, too. I had no choice but to do that between 2009 and 2013.