batteries and freezing

ws9876
ws9876 Solar Expert Posts: 440 ✭✭✭
can any of the agm s take sub freezing temps repeatedly???
has anyone put there batteries in a compartment 6-10 ft under grade to keep them from this???
got any pics,links..??

Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: batteries and freezing

    As I understand, AGM's are only 90% saturated fiberglass between plates--so any freezing still has room to expand without damaging the plates/case.

    On the other hand, a standard flooded cell battery at 50% state of charge will not freeze until 5F:

    http://www.buchanan1.net/lead_acid.shtml
    [FONT=Fixedsys]           Freezing,
    Percent  Specific     Degrees
     Charge Gravity  Fahrenheit
        100   1.265         -75
         76   1.225         -35
         74   1.200         -17
         50   1.150           5
          0   1.100          18
         <0   1.050          27[/FONT]
    

    Sinking a battery into the ground can be a help for both hot and cold climates (aka basements and other bermmed/earth protected battery installations).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset