How To: AGM Battery Maintenance and Care

Author: Jim McIlvaine, eCare Manager, OPTIMA® Batteries

Most people don’t think about their battery when it’s performing as it should, but rather, when something goes wrong. It always seems that something goes wrong at the worst possible time. Many AGM batteries, including OPTIMA Batteries, are manufactured to last for years. But how do you keep your battery powering through for that long without any issues? The keys include proper storage, correct charging and good maintenance.

Proper AGM Battery Storage

For many professional racers and enthusiasts, storing your car is a seasonal routine. However, all batteries gradually lose their charge when stored over long periods of time, potentially leaving you with a seemingly “dead” battery come spring.

Even when your vehicle is turned off, there still may be a drain on the battery. This is especially true of newer vehicles equipped with computers, alarms and satellite-based accessories that continue to run even when the vehicle is off. Over time, these can discharge a battery to voltage levels that are too low to start the vehicle.

You can considerably extend the life of your battery and avoid permanent damage by following a few easy storage tips.

First, before storing your vehicle, check the voltage to ensure the battery is fully charged (~12.6-12.8V for REDTOPs and ~13.0-13.2V for YELLOWTOPs). It’s important not to rely on your alternator to fully recharge the battery; instead, use a battery charger to top it off before storage. If it’s not fully charged beforehand, give it a boost with an OPTIMA Digital 400 or 1200 Performance Charger. OPTIMA chargers can charge batteries some other chargers cannot and are specifically designed not to overcharge your battery.

While in storage, we recommend using a battery maintainer to keep the battery at full power during the off-season. The OPTIMA Digital 400 and 1200 will safely charge and maintain your battery even during long-term storage with automatic restart in the event of power disruption, temperature-compensated charging and several unique features that prevent overcharging even in the event of battery failure. It’s an easy last step that will ensure a quick start when you’re ready to drive again. After your vehicle is stored, just hook up the battery maintainer—with the battery either in or out of the vehicle—plug it in, and walk away.

If you don’t have access to electricity where you store your vehicle, make sure your battery is fully charged and completely disconnected when the vehicle goes into storage. When you bring it out again, make sure to the top the battery off with a battery charger (not your alternator) before putting your vehicle back into service.

Correctly Charging an AGM Battery

An important key to maintaining a battery is charging it correctly. Newer chargers are equipped to handle the latest battery technology and are the best type to use with AGM batteries. Many newer battery chargers, like the OPTIMA Digital 1200 Performance Charger and Battery Maintainer are microprocessor-controlled, which helps adjust the charging profile and maximize efficiency and effectiveness in charging.

This is particularly important to help minimize sulfation in the battery. Sulfation can begin forming in any lead-acid battery once voltage drops below 12.4 volts, which is very common in vehicles that are stored for extended periods of time.

When charging any battery, it’s always best to charge it completely. Likewise, maintaining a 100 percent state of charge whenever possible is also best for the battery. OPTIMA Digital Chargers have multiple charge algorithms that auto-maintain at a 100 percent state of charge.

After charging is complete, the charger will enter into its auto-maintain mode, keeping your battery fully charged while minimizing sulfation. Periodically, the charger will “exercise” the battery by altering the charge profile, further enhancing the useful life of your battery.

How to Resuscitate a Deeply Discharged AGM Battery

Sometimes people encounter AGM batteries they presume to be “dead,” but are actually just deeply discharged. The best method for recharging a deeply discharged AGM battery is to use a good, modern charger, as previously mentioned, that can recover deeply discharged batteries. Both the OPTIMA Digital 400 and Digital 1200 can recover batteries that have been discharged as low as 1.25 volts.

By following these overall tips and tricks, you will help extend the life of your battery and keep your vehicle starting up year after year.

Want more best practices? Visit the “Tips and Support” section on for information on a variety of AGM Battery-related topics.