Different chemistries perform differently - slightly different initial voltages, very often very different curves as they discharge or age, sometime different performance given large or sudden changes in load (e.g. when an alarm sounds). I had a lot of problems with some early rechargeables for instance as their terminal voltage quickly dropped to a level where some equipment would object even though there was plenty of power left in them, and being labelled with the correct "nominal" voltage.
Different chemistries perform differently - slightly different initial voltages, very often very different curves as they discharge or age, sometime different performance given large or sudden changes in load (e.g. when an alarm sounds). I had a lot of problems with some early rechargeables for instance as their terminal voltage quickly dropped to a level where some equipment would object even though there was plenty of power left in them, and being labelled with the correct "nominal" voltage.
