Motorcycle batteries are six-volt lead acid batteries, small versions of the12-volt batteries used in automobiles. If you have a dead motorcycle battery that won’t accept a charge, the problem is normally sulfation. This occurs when a lead acid battery is deeply discharged, causing sulfur from the battery acid to adhere to the lead plates inside the battery and block the flow of electric current. The sulfur also corrodes the lead plates, but as long as the corrosion isn’t severe, you can fix a dead motorcycle battery without spending a lot of money.
Take the proper safety precautions. A motorcycle battery contains sulfuric acid, which is extremely toxic. Wear goggles and gloves and work only in a well ventilated area. Keep open flames away from the battery and always allow the battery to cool to room temperature before working on it.