Storage of rv with solar system

kcleetonkcleeton Registered Users Posts: 2
I have an rv with 360 watts of panal and 4 golf cart batteries.I will be storing this unit for about 7 months in Arizona beginning in April. The storage unit has a roof  but is not enclosed. I am considering leaving the batteries hooked up as there  should be enough indirect light to keep them charged. Please give thoughts on this. Would it be better to disconnect the batteries?

Comments

  • BB.BB. Super Moderators, Administrators Posts: 32,314 admin
    edited March 2017 #2
    If you do not have direct solar on the panels... Then they generally will not generate a useful amount of power (any direct shade will usually "kill" the output of the panels).

    If you have 120 VAC available, get a Battery Tender or Battery Minder type unit.

    http://www.batteryminders.com/
    http://www.batterytender.com/

    I have an older Battery Minder unit that I put on my in-laws' rarely driven car and it works great.

    I have also purchased "cheap" 12 volt @~1 amp maintenance chargers, and they all have been a horrible failure. Eventually, they boil the battery dry from too high of charging voltage.

    I do have one car on the cheap maintenance charger--But I use a lamp timer to only charge 1-3 hours per day--And that seems to work well (keeps up with the battery self discharge and all of those little computer loads that never really "turn off").

    Otherwise, for your batteries, I would get a ~20+ Watt 12 volt (Vmp~18 volt) solar panel, mount on the roof of the car port, and get an inexpensive solar charge controller to keep the batteries floating (make sure they are charged before you put on float--A float charger will not recharge a discharged set of golf cart batteries).

    And check the water level (and specific gravity) of the batteries once a month... At least at first. Until you are sure that they are properly maintaining state of charge and not "boiling dry/using water" during storage.

    -Bill

    PS: I would suggest a minimum of 4-8 amps of "float charger" for your four battery bank.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • EstragonEstragon Registered Users Posts: 4,496 ✭✭✭✭✭
    Also, depending on where in Arizona, temperature compensation might be needed? If really hot over the summer, lower voltages needed for float.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • BB.BB. Super Moderators, Administrators Posts: 32,314 admin
    edited March 2017 #4
    I should add... That your battery bank needs, roughly, 24 hours of "charging" with a good battery charger every 30 days (due to self discharge of the battery bank--And hot weather/battery bank makes self discharge faster).

    --If you do not have solar or other float charging setup for storage.

    If you let the battery bank set for more than ~1 month without charging, it will sulfate and slowly go bad. In 7 months of hot storage/no charging, the battery bank will probably be ruined.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • kcleetonkcleeton Registered Users Posts: 2
    Thanks for your suggestions. No option to use a charger or to add a small panal to the roof of the storage unit. My best option might be to remove the batteries and store them at my home in the north.
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