To determine the size of a battery required to run a series of electrical appliances in (say) a 4WD off-road vehicle, with fridge, lighting etc., use the following guidelines:
As you should not discharge a battery below 50% of its capacity on a regular basis, double this total. (105×2=210AH) This is minimum battery capacity required to provide reasonable service, assuming the battery can be recharged to full capacity during the next day, which may take 8 hours at 15-18amps charging. For the above example, if the applications are all 12 volt, two 6 Volt 220 Ampere Hour golf cart batteries connected in series will do the task.
These fast discharges don’t remove all power that is available, however this is all that can be provided by the battery to the voltage cut off point at that discharge rate.
e.g. GC2200 has a 75A rate of 108 minutes.
(Note electric golf carts are not drawing current all the time during 18 holes, they only use current when moving, not when stationary. During a 3-4 hour game, the carts may only be in use for 20-30% of the time).
Temperature affect on capacity
The ideal operating temperature for deep cycle batteries 25 degrees centigrade. Extreme cold or heat affects capacity and charging characteristics. To estimate the affect on cold performance for golf buggies, or other battery use, use the following estimates of reduced capacity at various low temperatures:
e.g. A golf cart battery of 220AH rating, will only provide 165 (220X0.75) amp hours at a temperature of 0 degree Centigrade……….. You may need to walk the last few holes, although the battery will still provide 108minX0.75 = 81mins of drive time. This should be OK, and besides at 0 Centigrade, the walk will keep the ice off your toes.