batteries and freezing

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