The most important tool is a Powersports battery charger/maintainer. Only use a battery charger that is designed for Powersports batteries.Using a Fast-Charge or Automotive-charger can permanently damage your battery. 

An inexpensive voltmeter or multi-meter is a smart investment if you have a number of vehicles with batteries to maintain.

If you own a Conventional battery, you should purchase distilled water to “top off” the cells when the electrolyte levels drop.

Wrenches and a screwdriver are required if you intend to remove the battery from your vehicle or tighten the terminal connections.

Baking soda, an old toothbrush, and wire brush to clean the battery and lead terminals.