Question: are all c batteries the same?
Answer: No, aside from the difference in size a standard C battery is 1.5 volt, the CR123a is 3.0 volt. ... The CR123a (same as CR123) is about 34mm tall and 16.5mm in diameter at 3volts. The original “C” battery measures 50mm in length and 26.2mm in diameter with a nominal voltage of 1.5volts.