How do you identify a battery that's not holding a charge?

Identifying a battery that is not holding a charge primarily involves checking its voltage after an attempted charge. When a battery is fully charged, it should exhibit a voltage that is close to its rated specification. If a battery shows significantly low voltage even after being charged, it indicates that it is unable to hold the charge properly. This low voltage is a direct sign of internal failure, such as a dead cell or some other malfunction that prevents the battery from storing energy effectively.

While there are other indicators of battery issues, such as leakage or unusual odors, these are not definitive signs of a battery failing to hold a charge. The weight of the battery can also be misleading, as different battery types and conditions can affect weight without necessarily indicating charge retention. Therefore, checking the voltage after charging is the most reliable method to determine if a battery is holding a charge effectively.