If at any time you witness a battery starting to balloon, swell up, smoke or become hot, discontinue the charging process immediately, disconnect the battery, and observe it in a safe place for approximately 15 minutes. This may cause the battery to leak, and the reaction with air may cause the chemicals to ignite, resulting in a fire.
Since delayed chemical reaction can occur, it is best to observe the battery as a safety precaution. Observation should occur in a safe area outside of any building or vehicle and away from any combustible material.
Wire lead shorts can cause fire! If you accidentally short the wires, the battery must be placed in a safe area for observation for approximately 15 minutes. Additionally, if a short occurs and contact is made with metal (such as rings on your hand), severe injuries may occur due to the conductibility of electric current.
A battery can still ignite even after 10 minutes.
In the event of any damage due to dropping the charger, you must remove the battery for observation and place it in a safe open area away from any combustible material for approximately 15 minutes.