RE: [Leica] SL battery help

[Jem Kime <jem.kime@cwcom.net>]

Jim,
Here's a condensation of previous chats on the SL battery problem.

'MERCURY FALLING'

Mercury PX625 PX13- 1.35 V are no longer allowed to be produced in the US 
or Europe. Those were the only countries with plants outside Asia. The last 
plant producing mercury cells was Varta in Ellwangen Germany. They were 
ceasing production in December 1999. The only place where their might still 
be production is China, but no-one there can find anything out about such 
production.

Alkaline PX625 1.5 V batteries are currently produced and available. The 
increased voltage can cause your meter to read incorrectly, but as long as 
the voltage in consistent, this can be accomplished by changing the ISO, or 
by a repair facility. Regardless, alkaline chemistry has a different 
discharge curve, meaning as the battery ages - its voltage is reduced.
The mercury puts out 1.35 for a long period, but as it begins to die the 
voltage drops suddenly. Alkaline batteries put out 1.5 v then it declines 
through 1.35 and finally dies. There is no indication that your battery is 
putting out, say, 1.2v and thus your meter is giving you a poor reading. So 
a meter on alkaline properly adjusted, will be fine, as long as your 
batteries are fresh. The level to which the batteries voltage drop will 
affect your transparencies exposure is up to your level of tolerance.

Two common alternatives are the CRIS adapter and the Wein cell.

The MR9 'C.R.I.S.' adapter uses AgO2 (Silver Oxide) batteries and their 
discharge is somewhat similar to the mercury. The sleeve accepts a common 
'Silver 76' battery and adjusts the output to the correct level through 
built in circuitry. The size is slightly taller than the old PX625 so your 
battery cover might live a little more proud than it used to. The cost is 
$30 and delivery from the US is not a problem.
http://www.criscam.com/mr9b.htm

The Wein cell is an adapted ZnAir cells, the equivalent for the PX625 is 
designated the MRB625. These cells were developed by Stan Weinberg and Bob 
Shell (editor of 'Shutterbug' magazine in the USA). They're manufactured in 
China for WEIN Products of Los Angeles and marketed by the Saunders Group 
in Rochester, NY., available here in Jessops and other stores, around a 
fiver a drop. They're supposedly the closest match for mercury having a 
voltage of 1.4V and a very similar discharge curve but with rumours of 
short life - up to 2 months. The battery also takes 30 minutes to arrive at 
operating voltage once the tab has been peeled off. If you buy this cell, 
when the battery dies, pop it out of the adapter, and put in a new ZnAir 
"76" cell. They don't last long once you open them, but they are quite 
inexpensive.

LEICA'S RESPONSE AND ANOTHER ALTERNATIVE

A couple of weeks ago I e-mailed Leica info service on the mercury battery 
problem for my SL and CL. Their response was some kind of standard letter, 
recommending the zinc-air button. In addition Leica service has bought some 
stock of mercury batteries which is expected to last for two years from now 
(but they did not quote their price). They did not mention the CRIS adapter 
at all.

Particular in bigger German stores, the mercury buttons are now difficult 
to find and their zinc-air replacements seem to be totally unavailable in 
625 size, now I search small shops for old stock of mercury cells. Last 
week I stepped into a special shop for hearing aids. The owner understood 
my problem well and even said that mercury is better for hearing aids, too. 
But he had no mercury and no zinc-air cells in 625 size. At the end he gave 
me little "six-pack" of PX675HP 1.4V mercury buttons. He did not want 
money. The weird story behind it is that (a) he is not allowed by law to 
sell mercury cells, that (b) a photo dealer next door sold them to me for 
money, and (c) that on the other hand some of his clients (war veterans 
etc.) still get mercury cells for their hearing aids free of charge from 
the German government who seems of have a large stock.

I found that the smaller PX675HP 1.4V works well in both my Leica SL and 
Rollei 35 which both have a metal screw-in cover for the battery 
compartment. Despite the 0.05V difference to the PX625 the light meters are 
spot on. Unfortunately the small 675 cells do make proper contact in my 
Leica CL or my Yashicamat 124G.

STORAGE ADVICE FROM VARTA

In response to your inquiry concerning optimal storage of the mercury cell 
V 625 PX, the electrochemical self discharge in primary batteries is 
considerably low.  For mercury cells the self-discharge is between 2% and 
3% per year at room temperature. Under optimal storage conditions, such as 
a refrigerator, the self-discharge rate will be slightly slower. A range of 
0?C to 10?C is a good temperature for storing batteries. To prevent 
oxidation it is recommended to store the batteries vacuum-packed, but do 
not store them in the freezing compartment, as inner structures of the cell 
would be destroyed upon thawing.
http://www.varta.com/
N.B.	The web site information should be read with caution, as it suggests 
inserting an 'AA' battery into a Leicaflex SL. One would need either a 
large hammer or no brain cells to contemplate this...

HOW ABOUT RECHARGING?

These old 1.35v mercury batteries can generally be recharged, so if you've 
got a stash of the things, it now makes sense to do so for practical, 
environmental and economic reasons. And those (silver?) EXP76 as used in 
the Leica M6 and just about everywhere else - those recharge beautifully 
too.

I had forgotten to turn the M6 shutter speed dial back to "B" and ran the 
batteries down to the point that the meter no longer worked. I recharged 
them in my solar button cell charger and got another 8 months of use from 
the things until I made the same mistake again. And again. I can't say 
exactly how many recharges these batteries will take as I'm still using the 
same set. If anyone wants info on those button cell chargers, it's item 
#BC300 near the bottom of the page at:

http://www.jademountain.com/energyProducts/battery/smallcharger.html

It's very simple and tiny--it hangs in your window and charges one button 
cell at a time. I may get 3-4 hours of direct sunlight at my house, and 
typically charge a depleted EPX76 for around 4 days or until open-circuit 
voltage is near 1.56V, same as a new one. Though great for silver cells, it 
was especially designed for mercury cells. It's made in Colorado, and to 
the best of my knowledge, there are no alternatives on the market.
Shipping overseas will be a bit higher than shown on the web order form, 
but it should still be pretty reasonable since it's so small and 
lightweight.

CONCLUSION

In summary, the two straightforward routes are either buying the MR9 
adapter from CRIS (for PX625 use) or buying the zinc air cells ready made 
from Wein. The recharging idea sounds emminently sensible too. First thing 
though is to ensure that present supply of available mercury batteries is 
used up. For more information useful sites are:
http://acecam.com/magazine/battery2.html
http://www.photobattery.com/index.html


=============================
hope this helps,
Jem


- -----Original Message-----
From:	Jim Hemenway [SMTP:jim@hemenway.com]
Sent:	08 March 2001 14:33
To:	leica-users@mejac.palo-alto.ca.us
Subject:	[Leica] SL battery help

Hello Luggers:

My not too badly abused SL has arrived.  I have no IB yet so I don't
know what type of battery to use.  I'm using the f2/50mm Summicron-R on
it.

I think that I have the meter working properly with a Varta V625PX -
1.35 volt Mercury battery which I've had in my refrigerator for a year
or so. I compared the meter against my Rolleiflex SL with a Varta V 625
U and they read the same.

We can no longer buy these batteries in Massachusetts, (and just about
everywhere else I've been told) so I'm wondering what to do when this
battery dies.  What is the Leica community common wisdom on this
problem?

I think that the Duracell 625A is 1.5 volts... can the SL be
recalibrated?

Thanks in advance,

Jim Hemenway
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