A broken busbar. This type of failure can be caused by excessive corrosion of the busbar due to low electrolyte level in the battery. Batteries with the capacity for higher electrolyte levels will help to ensure a longer battery life. It can also be a result of overcharging, cycling or elevated operating temperatures. Plate to plate short circuits occur when positive and negative plates make contact causing a short circuit, resulting in battery failure.
Vibration can cause the plates to wear or pierce the separator material leading to a short circuit.
Century Yuasa Batteries utilise strong Polyethylene Envelope separators which makes them less susceptible to this problem. Operating temperatures have a definite effect on battery life, and high temperatures will accelerate these 'end of life' conditions.