Motorcycles use sealed, lead-acid batteries---the same kind cars use, but smaller. While they both may be 12-volt batteries, most motorcycle types put out fewer amps and have lower, cold-cranking amps. In general, motorcycle batteries are more finicky and prone to "die" from sitting---although not from leaving lights or accessories on---and must be replaced more often. It's common to replace a motorcycle battery every 1 to 2 years. So, taking necessary care of the smaller, more vulnerable motorcycle battery can extend battery life and save you money and frustration.
The Three Tools to Recharge a Battery
There are a number of ways to recharge a weak or dead battery. A charger, usually only used by motorcycle shops and dealers, will fully charge a motorcycle battery in about an hour. Portable jump starters have become commercially popular, and can take the place of the dead or weak battery, temporarily. Once the motor is started, the alternator will recharge the battery.
Trickle chargers have their own application. If a battery is left sitting for long periods---weeks or months---it tends to loose its charge. A trickle charger, like the name suggests, provides a trickle of current to the battery, slowly charging it. The intention is to top off the charge.
How Some Trickle Chargers Can Damage Motorcycle Batteries
Using a trickle charger won't cause damage if you use it to top off the battery, then remove the charger. The problem comes after the battery is completely full and continues to receive current. True trickle charges don't have a mechanism to know when the battery is completely full. So, unless you monitor it frequently, it will overcharge the battery, shortening its life, or completely ruining the battery.
Float Chargers: The Smart Trickle Charger
Float chargers are a type of trickle charger, with a microprocessor to monitor and provide feedback from the battery. Sensing proper voltage, the charger discontinues its work until the float level drops, re-engaging the charger and avoiding costly battery damage and replacement. Float chargers are usually referred to as trickle chargers, not float chargers. There are several, including economy models from Chicago Electric Power Systems and the Battery Butler from Optima Batteries. Battery Tender was selected by Rider Magazine as the Product of the Year and rated number one by Motorcycle Consumer News.