How do I keep a car battery charged in storage?

Use a battery maintainer plugged into an outlet at your space. If there’s no outlet, disconnect the negative terminal so the car’s electronics can’t drain the battery while it sits.

With an outlet

A maintainer is the simplest fix. Clarios, which makes car batteries, recommends a maintainer for stored vehicles because it keeps the battery charged without overcharging it. AAA South Jersey says a battery tender “plugs into a standard 120-volt outlet,” and AAA Central Penn recommends one for cars parked through the winter.

Pick a maintainer, not an old style trickle charger. Battery Tender explains that a trickle charger “delivers a constant low current regardless of what the battery needs,” while a smart maintainer drops back once the battery is full. A maintainer can stay connected for months.

On this site, 251 facilities confirm power for vehicle spaces, and 26 of them mention trickle charging, batteries, or tenders. Ask whether you can leave a charger plugged in while you’re away, and whether power costs extra.

Without an outlet

Clarios says to “disconnect the negative terminal to prevent parasitic drain,” the small, steady draw from clocks, alarms, and computers. It also says to store the battery cool: “Keep it below 80°F.” A covered or indoor space helps in summer.

Before you leave the car:

• Charge the battery fully at home.
• Disconnect the negative terminal, or remove the battery and charge it at home.
• Check the voltage when you visit, and recharge if it’s dropping.

If you’ll store the car more than a few weeks, a space with an outlet is worth asking about. See how long a battery lasts in storage.