Archived posting to the Leica Users Group, 1999/06/18
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]In a message dated 6/18/99 5:45:44 PM Eastern Daylight Time, peterk@lucent.com writes: << Mercury have a constant 1.35v even as they expend their energy. This constant is why they were the prime choice in many cameras for metering systems. They also have a 10+ year shelf life where as Alkalines are generally 1/2 that at best. Alaklines have a 1.6+ volts even though they indicate 1.5v per battery with the drop off curve being slow and steep. At the end of their life cycle they will generally test about 1.35v where the mercury battery would normally be. Silver Oxide are a bit in the middle at around 1.55 volts. They offer more constant output, a linear drop off (not steep) and will provide a somewhat longer life than alkalines. Silver Oxide batteries offer a longer shelf life than Alkalines. >> Evidently then it is because Silver Oxide batteries are closer in discharge characteristics to the Mercury batteries (and basically just a series resistor is needed to adapt them) this is why the CRIS adadptor uses the MS76 (aside from the lucky fact it's also smaller than a PX13/625 and fits inside an adaptor). The big question is, why do the battery manufacturers only supply Alkalines in the PX13/6225 size, and not Silver Oxides? BTW I had a lot of trouble wiith those Zinc-Air Wein cells "replacements". Not only are they expensive, but they go dead in a big hurry. That is, if they're not already dead when you buy them, which was what happened to me. I finally had my Nikon FTn "converted" to take alkalines (this was before I'd heard about the CRIS adaptor) but dealing with the discharge curve is a royal pain. I rarely use the F any more, and if I do I have to check the meter against a different body at intervals and change the EI. DT