Re: A rechargeable PX625 replacement?

[rlocurto@pccsite.com (Ruth Locurto)]

When I was in the camera business I was told that the PX625A might
damage the fragile circuits in some older cameras, and that the readings
would always be off by an unpredictable amount - I was always worried
about selling them. I have seen allusions to solutions, but haven't had
concrete information, if anyone could dirct me to where this has been
covered I would greatly appreciate it.

PS does anyone know how to reach C.R.I.S. camera services?

Regards, Mark Wilk (rlocurto@pccsite.com)


- -------------------reply sep------------------------------

Doug Richardson wrote:
> 
> For some time, Ive been trying to find a replacement for the PX 625
> mercury battery used by classic cameras such as the M1 - M5, Cl and
> Leicaflexes. As a newcomer to LUG, Im aware that this problem has already
> been discussed, but I thought it might be useful to provide a summary of
> what Ive learned so far, and of a possible solution Ive found.
> 
> As result of restrictions which the US and EC are placing on mercury
> batteries, manufacturers have responded by creating the PX 625A. This
> generates 1.5 - 1.8 volts, rather than the 1.35 volts of the mercury cell.
> For most applications, this higher voltage is no problem, but it is
> incorrect for camera exposure meters.
> 
> For the moment here in the UK, mercury cells are still available, but
> its obvious that US supplies are rapidly dwindling.
> 
> There are only four realistic options:
> 
> 1 the Wein air-zinc battery
> 
> 2 an adaptor able to mount another type of battery into a PX626 holder and
> reducing the voltage of the cell to the level created by the mercury cell
> 
> 3 a rechargeable equivalent to the PX625.
> 
> 4   an adaptor which allows a small rechargeable battery to be fitted into
> a PX625 battery holder
> 
> (Theoretically there is a fifth option - for someone to devise a
> modification to the cameras and meters which would allow them to use a
> more modern battery - but this seems unlikely. It would involve modifying
> the Leicameter, M5, CL, Leicaflex, Leicaflex SL and Leicaflex SL2.)
> 
> What are Leica doing about this problem?   Nothing.  As Leica users, we
> need to find our own solution.
> 
> To date, I havent even seen a Wein cell, but according to discussions
> Ive seen on the internet and CompuServe, these are expensive and have a
> limited lifetime. Option 2 - a combined adaptor and voltage reducer sounds
> promising. One has been marketed since last fall by C.R.I.S. Camera
> Services, but I havent seen one or talked to anyone who has used this
> device, so dont know how well it works. If this had been discussed
> already, could someone copy the relevant postings to me?
> 
> Ive been focussing my attention on options 3 and 4 - rechargeable cells.
> Around 1970, a NiCad cell with the same shape as a PX625 was available
> from DEAC. This was known as the DK-50, but it is no longer manufactured.
> A present-day equivalent of the DEAC DK-50 might be a good solution, if
> one can be found. The number of people who use these classic cameras must
> be many thousands - not enough to justify a manufacturer putting a DK-50
> replacement into production, but Ive been trying to find a manufacturer
> somewhere in the world who still makes a cell of this type.
> 
> The overall dimensions of a PX625 are 15.5 - 16mm in diameter, and 5.5 -
> 6.2mm in height. The rim of the cell is of 15.5 - 16mm diameter, but the
> lower body of the cell was only some 12.5mm in diameter for most of its
> length.
> 
> Several companies in Pacific Rim and southeast Asia offer NiCads
> of 15.5mm diameter and 6.2mm height, but these are straight-sided, so will
> not fit the battery housing on most cameras. They would probably fit the
> Leicameter. Im still waiting to hear from one battery company in Hong
> Kong, but I think the chances of finding a rechargeable with the shape of
> the PX625 are remote. But Ill keep looking.
> 
> What I have located is a small straight-sided rechargeable with a
> diameter of 11.7mm and a height of 5.3mm. It would be a relatively simple
> task to make a small aluminum PX625-shaped adaptor which would allow this
> cell to fit our cameras.
> 
> The main problem I can see is that while the mecury cell produces 1.35
> volts, and the newer PX625A delivers 1.5 volts, the NiCad starts at around
> 1.3 volts when freshly charged, but soon drops to around 1.22 volts.  At
> around 1/3 capacity, its voltage then begins to decline sharply.  A
> nickel-hydride rechargeable of the same size is also available, but I
> havent any details of its discharge characteristics yet. The 1.5 - 1.8
> volt cell causes meters to read incorrectly (by a stop or more, Ive
> read), but what happens with a 1.2 volt cell? Does the meter read low by a
> stop?
> 
> According to my early-1970s edition of "The Leica Way", the DEAC
> DK-50 NiCad cell could be used in the Leicameter and Leicaflex, but the
> battery test deflection of the meter would be a little less than normal.
> No mention was made of any metering inaccuracies.  Does anyone have
> experience of using the DEAC NiCads in the Leicameter, Leicaflex, M5, or
> CL? If so, were they aware of meter errors?  How long did the battery hold
> its charge?
> 
> Regards,
> 
> Doug Richardson