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profdant139's avatar
profdant139
Explorer II
Aug 05, 2015

Do I need to "top off" the battery if it is fully charged?

I keep my batteries on a BatteryMinder Plus. I recently got a portable solar panel that puts out about 14 volts in full sun. If I hook the panel to a fully charged battery just before a camping trip, does that really accomplish anything? Or is the battery already as "full" as it can get?

And if hooking up the solar panel is helpful, how do I know how long I should leave it hooked up? (Obviously, when we are camping, I leave it hooked up all day, since there is always a parasitic draw on the batteries from the fridge, etc.)

Sorry if this is a naive question, but a search of the archives did not turn up a clear answer. Thanks in advance for your advice!

46 Replies

  • profdant139 wrote:
    2oldman, yes I am connecting the panel to the battery.

    And Mexicowanderer, how does one create a charge greater than 14 volts? That's all the panel will produce. And the three stage converter in the trailer maxes out at about 13.5.


    In the site search bar enter

    TOP CHARGING

    page after page of discussion. Of course if I write one word of alternatives to PHART CHARGERS Einstein-grade level of intelligence somebody's going to pipe up and complain.
  • How are your measuring the 14v output from your panel?

    https://www.youtube.com/watch?v=Hey1QZkYFSQ

    Does the panel have any info on the back like watts, volts etc that you can share? Make/model?

    I'd leave the panel attached till a volt meter indicated 15v at the battery, in hot temps I might disconnect before 15v.
  • You didn't get any advice about foregoing a solar controller on here. You don't mention how many watts this panel is.
  • 2oldman, yes I am connecting the panel to the battery.

    And Mexicowanderer, how does one create a charge greater than 14 volts? That's all the panel will produce. And the three stage converter in the trailer maxes out at about 13.5.
  • Months and months on a battery minder can leave a battery hungry for a top charge which is completely different than 14.0 volts on a solar panel. The top charge is for battery longevity and not especially to increase instant gratification capacity.
  • profdant139 wrote:
    If I hook the panel to a fully charged battery just before a camping trip, does that really accomplish anything?
    no.

    Are you connecting the panel directly to the battery?