- The battery heats up and smells charred. There seems to be a chemical reaction going on inside the battery. Do not continue to use the battery and store it outside the house. Never try to extinguish with water but use sand or other fire retardant and call the fire brigade.
Replace the battery as necessary.
- The battery case is torn / damaged. Moisture penetration cannot be entirely precluded, and damage to the cells by falling or impact is also possible. Do not continue to use the battery and store it outside the house. Replace the battery as required.
- The battery contacts are no longer shiny and are corroded. The contacts can be cleaned with a soft cloth.