PX28A battery
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| PX28A battery, with a AA cell for comparison. image by joanseda (Image rights) |
Many cameras can use a 6-volt PX28 battery; examples include the Canon A-1 and AE-1, Mamiya M645 (and the Super, Pro etc.) and the Bronica SQ and other medium-format SLRs.
The battery has a diameter of 13 mm and is 25 mm tall; roughly half the size of a AA battery. It is also denoted as PX28A or simply 28A[1] by some makers, or 4LR44 if of alkaline magnesium chemistry, or 4SR44 if silver oxide.
The charge capacity of the alkaline battery is stated differently by different makers: Duracell's 28A alkaline cell is said to have a capacity of only 105 mAhr; Camelion claims a capacity of 165 mAhr for their 4LR44, and 145 mAhr for the 4SR44. The silver oxide battery has a slightly higher voltage of 6.2V.[2]
The battery is functionally equivalent to four 1.5-volt LR44 or SR44 cells, though four of these are smaller than the single 6-volt cell, so a battery compartment will need to be padded if they are to be substituted.
