Battery for Compur electronic

**Karo from Moscow** · 17-Oct-2003, 14:18

Does anybody know where to buy PX-21 battery(or analog)for Compur electronic shutter?
thanks.

**Michael S. Briggs** · 18-Oct-2003, 00:39

A web search turned up several suppliers listing it, which is no guaratee that they have the battery. http://www.smallbattery.company.org....k/sbc_px21.htm had the most information. I have the same battery that they show in their photo for my Compur Electronic 3: an "Exell A21 / A133 4.5V Alkaline&quot. The battery label also lists alternative designations 523, PX21, EN133A and PC133A. Another useful source of information is the datasheet for the discontinued Eveready Energizer 523: data.energizer.com/datasheets/library/discontinued_batteries/ manganese_dioxide/523.pdf. This also gives standard organzation names ANSI 1306AP and IEC 3LR50. These names are also listed by www.smallbattery.company.org.uk. The most common names seem to be PX21 and 523. These two names and the standard organization names will probably be most useful in searching for the battery.

The websearch turns up that this battery was used in various older cameras including Polaroids and also in some older Macintosh computers. Some suppliers on the web are for Mac computers. Some other suppliers found with google are Adorama and http://www.photobattery.com. In the US you can order it by mail from Radio Shack or special order it at one of their stores: type "960-0357" into the search field on their webpage http://www.radioshack.com. Their webpage also confirms 4.5 V Alkaline, 1306AP, 3LR50, 523 and PX21. (Radioshack may have the best price.)

The battery is a 4.5V Alkaline. The Energizier data for the 523 gives the dimensions as 16.46 to 16.85 mm diameter and 48.44 to 48.84 mm length. The measured dimensions of the Exell A21 / A133 that I have are consistent with these dimensions. The instructions for the Compur Electronic 3 state "The shutter has been adjusted for a battery voltage of 3.8 plus/minus 0.4 V.".
This is a little peculiar since 3.8 + 0.4 = 4.2 V, yet the battery is nominally 4.5 V. The instructions go on to state:
"If the PX21 battery cannot be obtained, however, batteries for a voltage range from 2.6 to 6.0 volts can, if necessary, be used without danger to the electronic system.". With this information I hope to identify a more available battery that can be substituted.