BATTERY STORAGE
Over time, batteries self-discharge, even when disconnected. Some new batteries
may have a self-discharge of 1-2% per month, but depending on the type and age
of the battery, it can rise to 6% per month or more.
If the battery is coated with moist dirt and corrosion by-products, discharge rates
can be even higher. Make sure the battery is clean and free of dirt and corrosion on
and around the terminals.
If the battery is a flooded type, top up the electrolyte, ensuring that it is above the
plates and below the vent cap well.
Fully charge the battery before storage, and store in a cool, dry place. Cooler
batteries will self-discharge at a lower rate than warm batteries.
Check the terminal voltage of the battery periodically. When the terminal voltage
drops below 12.4 volts (75% capacity), charge it until fully charged. More frequent
charging is preferred if convenient. It is recommended to charge the battery every
three months.
Note that as charge capacity decreases, the freezing point of the electrolyte
increases. This is important because the electrolyte must not be allowed to freeze.
At 62% capacity, the freezing point is -26.5°C/-16°F; at 85% capacity, it is -52°C/-
62°F.
CONNECTING 12V BATTERIES IN PARALLEL TO BOOST CCA
You can double the CCA supplied from a single battery by connecting a second
battery in parallel to the first. You may prefer this alternative to buying a larger
single battery with the required CCA rating.
Figure 1: Two batteries in parallel, doubling CCA
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