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Solar panels/ batteries

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We have 4 Ganz 55 panels and are looking for suggestions for increasing battery capacity. Our main drain is running an Isotherm 160 ref/ freezer.
We are currently using 2 12 V wet acid batteries. It has been suggested that switching to 4 6 V batteries would increase storage. More panels? More batteries? Thanks for suggestions.

4 Replies

  • A few questions that would help get a good answer.

    What do you perceive the benefit of additional battery capacity?

    What is the real challenge you are looking to solve? Is solar power being wasted because

    Which solar charging controller and batteries do you use? What kinds of boat, how do you use it?

  • Additional storage so refrigerator can run without depleting battery capacity.we have a Ganz 10A comtroller and Xantrex inverter.
    Plan on replacing batteries with better quality- AGM's?
    Boat on mooring, used frequently . New lobster cruiser, simple set up.
    Thanks for your suggestions!

  • Only if more solar power is generated than there is battery capacity to store it, will adding capacity help. For example getting you through some dark days.

    Some things to consider
    - Are you ok doing maintenance (adding water to the batteries)
    - Some batteries are damaged by standard alternators. Do you only want to consider batteries that work well with them, or are you willing to upgrade to a charging system with a new alternator and a charging contoller like these
    - Some batteries need to be frequently full charged to avoid lasting loss of capacity
    - Are you stuck with a certain physical size battery

    Look first at 6V Golf cart batteries, like those offered by Deka. Use 2 or 4 of them to output 12v. They take deep discharges to 80% very well, they work good with standard alternators, they are cheap, but they are an odd size and they cannot be left discharged for long.

    Next look at the Panbo post, and consider if you want one of the batteries mentioned there. Look at the practical sailor article mentioned. Consider if you choose one of those other batteries, do you also have the expense of upgrading your power system vs using a standard alternator.

    If looking through that information isn't something your able to do, then simplify it to compare the golf cart batteries to the Firefly and see if you can make a decision looking just at those two.

    Panbo post to look at:

    Lastly, consider adding a smart gauge to your boat before you make a battery purchase. This will do three things for you. (1) you can objectively understand how deeply you are discharging and recharging your current batteries before making a battery purchase (2) you can better manage your power in general, maybe cost avoid buying additional battery capacity (3) you can take better care of your new batteries so they last longer. (4) you can see a difference before/after changing to new batteries. Read about a smart gauge here:

    Be sure to write back and let us know if you have more questions and write to tell us the decision you made and how its working for you.


  • The firefly needs an upgraded alternator/regulator also.

    There is a lot to be said for the golf cart batteries in that your electrical system stays simple.