[ausev] Cold weather and lead acid batteries

[Ken Thomas]

I got some resistance wire, 25' of HWR-21168 from 
www.refrigeratorparts.com and a couple pop-switch thermostats, stock 
number 802-STO-60, from www.mouser.com.

All 25' of the resistance wire was snaked around the batteries.  The 
batteries are split into two compartments so a thermostat is installed 
in series with each section of resistance wire.  Each compartment gets 
1/2 of the 25' but it is all wired in series.  So, either thermostat 
will turn the whole thing off.

The heater wire system draws 1.9 amps at 120 volts or 228 Watts.  The 
wire is 2.5 Ohms per foot.  The thermostats will keep the compartments 
at about 50 degrees Fahrenheit.  Still a bit cool but much better than 
30 degrees.  It will never turn on above 50 degrees.

The 1.9 Amps is low enough that it can be paralleled across the charger 
input without undue mains load while charging.  I just leave it plugged 
in all night (which I always do anyway) and it keeps the batteries from 
getting lethargically cold.

Thanks,

Ken