Without regular use, a motorcycle battery can lose its charge. While you can charge the battery when it's dead, a better choice is to use a trickle charger. Using a trickle charger, rather than allowing the battery to completely lose its charge, will help prolong the life of the battery.
Attaching Harness or lead to Battery
Access the motorcycle's battery using the procedure outlined in your motorcycle owner's manual or service manual. This may require tools. The battery could be located under the motorcycle seat or behind a cover.
Remove the battery following the instructions specific to your motorcycle, if you don't have access to the battery terminals.
Install the terminal harness to the battery, if desired. This step is highly recommended if you had to remove the battery or if it took you more than five minutes to access the terminals on your battery. If you choose not to install a permanent harness, clip the trickle charger's lead to the terminals. For either the harness or the lead, follow the color code to ensure that the positive clip on the lead is hooked to the positive terminal and the negative lead to the negative terminal.
Plug the harness or lead into the trickle charger.
Charge the battery
Plug the charger into the electrical supply.
Check the charger periodically and unplug the leads when the battery is fully charged, if the charger does not self-regulate and switch to float mode.
Leave charger connected. If the charger does switch to a float mode, it can be left on the battery indefinitely.
It is highly recommended that you use a charger that will self-regulate and switch to float mode when the battery has reached its maximum charge. This enables the rider to keep the battery on the charger for extended periods of time, such as the winter months, without the concern of overcharging the battery.
Some chargers either come with a terminal harness, or the harness is available as an accessory. The harness can be left on the battery permanently, making charging much easier. The connector can also be used to charge other accessories, such as a cell phone, or to provide power to heated clothing while riding the motorcycle.
Know your charger! If you don't have documentation, or the documentation doesn't specifically state that the charger will float, you must disconnect the charger when the battery is fully charged.