Battery Storage: Use a Battery Maintainer
You've emptied the gas, sealed the exhaust and prepared the engine for seasonal storage. But before you throw the tarp over your boat or roadster for the long winter sleep, think about how you're going to care for the battery.
Batteries lose their charge when they sit idle, and when that happens, you could wind up with a worthless battery in the spring. To keep batteries healthy, they should be charged every six weeks. But leaving a standard battery charger connected for the whole season isn't a good idea—that will overcharge the battery and shorten its life. Instead, invest in a “battery maintainer.”
Battery maintainers are designed to be left on for the entire off-season. They monitor battery voltage and automatically adjust the charge to avoid under- and overcharging.
Battery charger/maintainers and quick-release terminals are available at most auto parts stores or online.