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Batteries can last for over five years with minimal care in a car that is driven regularly. However, when a battery is left unused, outside of a vehicle, it can become worthless in less than six months. How can a battery last so long in a car, but when left unused, it dies so quickly?

When your car starts, the engine runs, which powers the alternator keeping your battery charged (assuming you have a fully functioning alternator). But what about your boat battery that sits for three months during the off-season, or any lead-acid (standard), AGM or Gel Cell battery that is not regularly used?

When a battery sits unused and not properly charged it’ll go through a process called sulfation (usually within three months). Sulfation is when the battery’s electrolytic solution becomes so weak that the sulfur molecules from the solution stick to the lead plates in the battery and eventually become crystals. The crystals coat the plates, which minimizes your battery power. Even worse, the electrolytic solution that was converted to crystal lowers the battery electrolyte level making the battery even weaker.

In the off season, an athlete must continue to exercise in order to stay at the athletic level that he / she was at during the regular season. If they sit around on the couch for six months, they’re going to be out of shape and unable to perform at their optimum level the following season. The same concept applies to your battery. To keep your battery in great shape, it must exercise regularly; in other words, charge your battery regularly (at least once a month).

To prevent sulfation, your battery needs to be kept fully charged. There are a few ways to always keep your battery at a full charge:

1. Charge your battery at least once a month using one of Schumacher® Electric’s SpeedCharge® units. (See below for proper charging pointers.)
2. Maintain the battery using a Schumacher® Electric maintainer, which comes in 1.5 ~ 3.0 amps, or any of their SpeedCharge® units.

What’s the difference between charging and maintaining? Charging is used to quickly bring the battery to full capacity, while maintaining is used to keep the battery fully charged for long periods of time.

Maintainers are slow chargers that keep your battery at a full charge, all the time, in one of two ways. They will either float the battery between 13.1-13.5 volts until you disconnect it or they will fully charge the battery up, turn off and stay off until they detect that the battery’s capacity is dropping. Then they will turn back on and repeat the cycle.

After the battery is fully charged, use the Schumacher maintainer to do the work for you. Hook it up to your battery once and forget about it until next season!

1. Check your battery post and battery cables for corrosion. Also check to see that the battery fluid is at the recommended level (if applicable).
2. Determine whether your battery is 6- or 12-volt (most vehicle batteries are 12-volt). Then determine if it is a Standard, AGM, or Gel Cell. If you are using a manual charger you will also need to know the amp-hours (AH) or reserve capacity (RC) to calculate the battery charge time. Automatic chargers, as the name implies, properly charge the battery, shut off and enter maintain mode when finished. Manual chargers must be monitored to prevent over-charging!
3. Choose a charger. Select a charger to match your battery voltage (6V or 12V). NEVER try charging your battery at the incorrect voltage. Next, select a charger with enough power to properly charge your battery. The rule of thumb for charging batteries is to use 10-15% of the AH of the battery.
   For example: If the battery is 100AH, charge it anywhere between 10-15 amps. If you go below these numbers, you will sacrifice getting the battery fully charged. And don’t believe the old myth that charging Deep Cycle batteries at low amperages is better for the battery. It will actually cause the battery to be under-charged, resulting in a loss in Amp-Hour capacity.
4. Connecting the charger. When the battery is in a vehicle, connect to the positive battery post first. Always make the last connection to the vehicle chassis ground away from the battery. Then plug the AC cord into the electrical outlet. Reverse procedure to disconnect. (See the battery charger owner’s manual for more details.)
5. When is the battery fully charged? An “Automatic” charger will turn off and go into maintain mode when the battery is fully charged. A “Manual” charger must be monitored to ensure that the battery does not over-charge. Read the ammeter or charge indicator on the charger to determine if the battery is at full charge. When the amperage lowers to half of the set amperage, the battery is full
   For example: If the charger is set to 10 amps and has charged the battery for the calculated run time, the battery is full when the charger reads less than 5 amps.

^{Written by Jonathan Hardges.}

^{Copyright © Schumacher Electric Corporation 2008. All Rights Reserved.}