battery question

krismankrisman Solar Expert Posts: 57 ✭✭✭✭
my solar panel is 12v, 50 watt with a 12 volt solar charger, and i have a 12 volt marine battery i guess a small one i have no idea the size. anyway the charger says it cuts in at 13.2 volts and cuts off at 14.2 volts. i have never saw the battery go beyond 12.5volts when charged, sometimes it would get up to 12.8 but then go back down to 12.5 when the sun went down. i was just wondering if it would hurt the battery to keep it hooked up till when i needed to use it or if there was a chance the battery could explode?


  • BB.BB. Super Moderators, Administrators Posts: 32,093 admin
    Re: battery question

    It does sound like like sound like a problem. Perhaps the solar charger/panel has issues--or you are taking too much power during the day (if you are using any power).

    You sort of need to go back to the basics--measure the solar panel voltage, panel current, and battery voltage (solar panel voltage should be higher than the battery voltage by about 1-2 volts during charging, by 3-5 volts if the charger believes the battery is near fully charged).

    And what is the panel's Vmp/Imp rating--and what is the battery charger (any meters, LCD, LED displays, etc.).

    Also, should measure the current (PV current or controller to battery current).

    If you have a load attached--can you disconnect until you are sure the battery is charging/charged?

    lastly, it is possible the battery is no longer any good (shorted/bad cell, not being charged properly, etc.).

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: battery question

    it may be undercharging the battery. i think it could easily go to 14.4v (safe area for most agms) if not 14.5v for a standard lead acid battery with some manufacturers wanting that to go even higher before the bulk stage ends. i don't know what charge controller you may have, but try upping the voltage on it if it is able to. do not drain off the charge until you know the battery has become full as sulphation can occur in undercharged batteries and it may have started on yours as i suspect your charge percentage may be low too based on your pv wattage.
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