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bdoyle's avatar
bdoyle
Explorer
Apr 23, 2018

Reviewing Solar and batteries for retirement

Hello, I have a fiver that hasn't had it proper share of use and we are now getting ready to fix that issue. We tend to dry camp but will utilize campgrounds if available. We had solar (120 X 2) and inverter (Xantrex 458 2500 combi) installed in 2003. Batteries have always been an issue due to lack of use and maintenance. I have gone thru 2 sets of batteries (6v X 4) and ready for a third set. Uses lots of water and was thinking that the solar was cooking them. Controller is a Mark PV 22 by Specialty Concepts. Charge was set to 14.4 but I just backed it down to 14.1, so I hope to make them last a bit. We tend to hit the batteries hard in the morning but they can charge up all day with the solar.
Usage:
Hair dryer: 1600 Wts 20 min 53 amps @ 12v?
Coffee maker 870 Wts 20 min 29 amps @ 12v?

Maybe I need 2 more batteries for a bank of 6.
Thanks!
Brian Doyle
Silver Springs, NV

42 Replies

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  • time2roll's avatar
    time2roll
    Nomad
    Apr 23, 2018
    Most 6v GC2 charging specs are 14.4 to 14.8 range. You might be undercharging at 14.1 volts. You might be undercharging at 14.4 volts if the controller drops to float too soon. Need at least two hours of absorption each day when in use and maybe more than six hours. Although 14.1 might be Ok for the aged batteries to reduce water usage until they can be replaced.

    I recommend some new new solar closer to 400+ watts considering your usage.
  • KD4UPL's avatar
    KD4UPL
    Explorer II
    Apr 23, 2018
    You need to find the charging voltages your battery's manufacturer recommends; both bulk and float voltages. They may also have recommendations for maximum charge rate, temperature compensation, length of absorption phase, etc. Then you need to properly program your charge controller to the specs. Just guessing can get you close but may leave you with chronically over or under charged batteries.
    Using lots of water normally indicates overcharging or old, worn out batteries.
    If your charge controller doesn't allow you to program it specifically for your batteries you may need to invest in a better one that will.

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