How can I tell if my battery has reached the end of its useful life?

Different types of batteries use test procedures that allow different end of life criteria. For example an electric vehicle or standard deep cycle product would be considered to be at its end of life when it was not able to deliver 50% of its rated capacity while a golf cart battery would not be determined to be at its end of life until it was not able to produce at least 1.75 volts per cell during 40 minutes of discharge at 75 amperes. Most official tests to determine the cycle life of a battery are performed in laboratories, under controlled circumstances and temperatures. For the average user, it is important to make sure that the battery is being charged properly and that the temperature during evaluation was not extreme. (between (18˚ and 28˚C for example)