Off-Season Battery Maintenance and Charging

Batteries periodically need exercising and maintenance to prevent sulphation from building up on the battery plates. Batteries that sit unused for a long period of time (longer than four weeks) need a maintainer.

Consider a water fountain in the middle of a cold winter. The water freezes because it sits dormant. Running water never freezes because the molecules are always in motion.

The same is true for your batteries. Maintaining the battery keeps the molecules in motion. When maintained, sulphation won’t rear its ugly head (just like the ice in a flowing fountain).

Battery Sulphation

Once the plates become sulphated, the battery sees a reduction of run time or starting capabilities that worsen with time.

Other problems can occur when trying to charge a sulphated battery. While the charger tries to charge the battery, the battery plates do not accept the charge. The charger stays in constant charge mode and can overcharge a battery, which will cause it to swell or burst. Automatic chargers will only shut off once it sees the battery is fully charged. In other cases, the battery voltage is so low the charger cannot read the battery and thus goes straight into its float/trickle mode without doing anything to the battery.

Choosing the Correct Maintainer

The type of battery determines what charger/maintainer to use.

For example, a standard starting battery in most cars, any 1 to 3 amp fully automatic unit will work fine for maintaining throughout the winter.

Choosing the correct charger/maintainer depends on the amp hour or reserve capacity of the battery and whether you want to charge or just maintain the battery. The higher the amp hour of a battery, the higher the charger amps you’ll need to charge the battery. For maintaining only, a lower amp charger will work.

Below is a general size chart for choosing the correct charging amps for many SLA rechargeable batteries:

Battery Amp HourRecommended Amps of Charger
Under 7 AH500 – 750 milliamps
7 – 20 AH1 – 2 Amps
21 – 40 AH2 – 3 Amps
41 – 75 AH3 – 5 Amps
76 – 100 AH6 – 10 Amps
101 – 125 AH10 – 15 Amps
126AH+15 – 20 Amps

You can estimate charging times with the following formula: (Battery Capacity) / (Charger amps) = Charging Time

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