How to store a car battery

Connect a battery maintainer if you’re going to store a car battery for long periods

Charge your battery before storing it

If you follow the storage conditions shown here, you can count on your battery losing about 3% of its charge per month. Battery sulfation begins when the battery discharges to 60%-70% of its charge. When left to discharge further, the lead sulfate crystals can harden on the plates and permanently reduce the battery’s capacity.

Use a battery maintainer to keep your battery fully charged while being stored

A battery maintainer is similar to a trickle charger

Clore/Solar ProLogix PL2140 battery maintainer

but with a big difference; it stops charging when the charge reaches 100%. It then monitors the battery voltage and starts a charge only when needed.

What’s the difference between a battery maintainer, trickle charger and float charger? See this post for the answer.

Clean the terminals and the battery case

Moisture condensation on the battery case and terminals

Battery terminal protection spray

can cause transient power loss. So it’s best to clean the case and wire brush the battery posts before storage. Then treat the posts with a corrosion reducing spray.

Choose the right location to store your battery

A cool, but not cold location is best for battery storage. Choose a spot that’s between 50°F and 60°F with low humidity.

All batteries self discharge when not used

Depending on storage temperature, a car battery can lose up to 2% of its charge per week of non-use. And that’s with it disconnected from the vehicle. If it’s connected, the constant computer power usage can completely drain your battery in 4-6 weeks.

Car battery storage myths

Myth #1: Never store a battery on a concrete floor

FALSE: Storing a car battery on concrete does NOT damage the battery

Transient power loss occurs any time moisture accumulates on the battery case. It’s not the concrete that causes car battery discharge; it’s condensation/moisture accumulation on the top of the battery case. If you follow the storage recommendations above and keep the battery stored in a cool dry location, it doesn’t make any difference what surface it’s stored on.

Myth #2: A new battery can be stored indefinitely

FALSE: While it’s true that a new battery self discharges at a much lower rate than a used battery, a new battery should never be stored longer than two years. Even if fully charged, a new battery will still lose charge and long term capacity if kept in storage longer than two years.

For best long term performance, new batteries should be put into service within 6-9 months after manufacturing.

Deep discharges cause plate degradation in lead acid batteries. Deep discharges shorten the life of the battery.

©, 2023 Rick Muscoplat