NiCd batteries cool as they arerecharged because reversing the cell reaction absorbs heat energy. ... Early cells suffered from a memory effect in which the cell would “remember” how far it was discharged during the previous cycle and only discharge to this level, reducing the overall charge...
While mercury batteries can be recharged, chargers built to handle more than one type of battery would have to be a bit more elaborate, because of the variety of sizes and voltages. Danger of explosion is greater than with other types of cells. You can blow up a carbon-zinc cell, bu...