STORAGE BATTERY PERFORMANCE AT LOW TEMPERATURES 430132
PLENTY of heat is the best solution to the problems encountered in using storage batteries at low temperatures, the authors say.
Starting at low temperatures is difficult for two reasons. A cold engine requires higher torque to start it, and the colder the battery the less the amount of current that can be drawn from it.
With a 24-v battery, an engine requires to start it at a certain temperature only one-fourth the amount of current it would require if the battery were only 6 v.
After an engine has been started, it is necessary to put back the energy taken out plus a little more because battery charging is not 100% efficient. This cannot be done at low temperatures. For efficient charging, the battery temperature should be at least 40 F.
For batteries that are used fairly frequently, it is helpful to keep them in well-insulated boxes, or in boxes that have had a piping system rigged up so that warm water can be circulated through the boxes. Another solution, satisfactory for batteries having rubber cases but not for those having composition cases, is to use a suitable heater. If a battery has been parked for days, even a well-insulated box is not enough, so that some sort of heater must be used. One type of heater in successful use is the Coleman No. 520 gasoline burner, which supplies 5000 Btu per hr. About 45 min should be allowed to heat the battery with this burner, before it can be used for starting.