Mercury Cells
From Camerapedia.org
Mercury cells (also referred to as mercury batteries) are batteries with a mercury oxide electrode. The manufacture, transport or sale of these batteries is banned or restricted in many jurisdictions. Before such bans, many cameras and lightmeters were designed to use them. Because mercury batteries produced a constant and reliable voltage, these devices were built without voltage regulation circuitry. Unless remedial measures are taken, use of other kinds of batteries gives inaccurate meter readings and therefore incorrect exposures.
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Devices requiring PX625
Many cameras and lightmeters where designed for and require a 625 mercury cell: list of cameras and list of exposure meters. Some cameras and exposure meters were designed for 625 sized cells but include voltage regulation circuitry and thus do not require a PX625 to function properly (list of devices).
Cell Names and Sizes
Mercury batteries came in number of different sizes including the 32, 400, 625, 640, 675 and the like. Most of the mercury batteries are a single electrolytic cell. However, the 32 is a set of 4 stacked 640 cells. The greatest number of cameras, finders and light meters were designed for the 625.
| Common Number | Alternative Names | Diameter(mm) | Height(mm) | Mass(g) |
|---|---|---|---|---|
| 625 | 1124MP, MR9, PX625, PX13, EPX625, RPX625, KX625, HD625, PN625, RM625, 625, H1560, H-D, MR9 | 15.6 | 6.05 | 4.5 |
| 675 | 1128MP, MR44, PX675, HD675, KX675, RPX675, H-C | 11.6 | 5.35 | 2.6 |
| 400 | 1116M, MR42, E400N, EPX400, KX400, PM400R, PX400, RM400, T400N, V400PX | 11.6 | 3.6 | 1.4 |
| 640 | 1105M, NR52 | 16 | 11.2 | 8 |
| 32 | 1404M, 4NR52, PX32, E164, TR164, 4NR52, 1404M. HM-4N, V164PX, PX32A, PX32B | 17 | 44.5 | 36 |
