1993 Ezgo Battery Set

[JohnnieB]

Originally Posted by fencible39

Thanks for that info.

The temp in my garage got in the single digits that year when it froze.

The digital LED gauge I installed shows the actual voltage of the set. I'll keep it above 36.5 and charge it at that point.

Attached a SoC (State of Charge) chart for US Battery brand cart batteries that includes the electrolyte's freezing points at various SoC. Trojan brand batteries use a slightly higher acid concentration and will go a few degrees lower without freezing when fully charged.

If your cart is unused for weeks at a time during the cold months, get a charger that float charges. (Puts out a constant voltage that is above the at-rest voltage for 100% Soc, but below the gassing voltage.)

Or get a battery maintainer and use it to keep batteries fully charged.

The higher the average SoC maintained, the longer the batteries last.

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Batteries have less storage capacity (runtime) and performance when cold, so using some method of keeping batteries warm is beneficial if cart is to be used in cold weather. Other than that, just keeping them at 100% SoC is sufficient down to about -70°F.

[ThreeCW]

As JohnnieB points out in his freezing point chart, the best way to keep a battery from freezing is to keep it charged ... and keeping your battery pack charged in the 90 to 100% range will prevent it from freezing at any temperature that you will experience in North America.

Battery heaters can be used (although infrequently) in cold climates for starting batteries to get the most energy out of your battery in low ambient temperatures ... the primary use of them is NOT to prevent your battery from freezing.

Perhaps a maintenance charger would be a better use of electricity in your case than a battery warmer ... to keep your batteries from freezing and to prolong your battery life. You will want to keep you batteries above 90% state of charge or 37.9 volts ... the 36.5 volts you are referring to is only a 50% state of charge ... a 50% SOC will lead to sulfation of the batteries and a shorter battery life.