PX625, Best Mercury Battery Substitute Solution For Use In Leica M5

<p>I have recently acquired two Leica M5 bodies which I have sent to Golden Touch for CLA. Sherry Krauter has advised me that the Mercury PX625 battery recommended in the Instruction Manual is no longer available today because of environmental concerns. Sherry ticked off several other options for powering up the Leica M5 meter, all seeming to suffer some disadvantage when compared to the original PX625, Leica recommended battery. Sherry said she could, "re-calabrate", my M5 meters to use some other button cell battery, but I forgot which one she was talking about.</p>

<p>Also available, are <a href="http://www.weincell.com/">WeinCell</a> batteries, which Sherry Krauter does not recommend because of wide fluctuations of battery life due to relative humidity, and a propensity to quickly corrode if left in the M5 after the WeinCell's useful life is over - apparently, sometimes just a few months! To activate the WeinCell, it must be unsealed and exposed to air for at least 30 minutes, but occasionally this activation time can be much longer, depending upon atmospheric conditions.</p>

<p>I'm guessing the original PX625 is still manufactured somewhere in the world, because it is such an efficient battery, and many areas of the globe are more lax, environmentally, than most of us. Still, does anyone know of a web site where this battery may still be purchased? </p>

<p>I see many mercury PX625 battery problem solutions described on the internet, from altering a modern battery to replace the PX625, to re-calabrating the M5 meter to use another battery, to DIY battery adapter kits, to pre-made options. The <a href="http://www.criscam.com/mercury_battery_adapters.php">C.H.R.I.S MR-9</a> is one of those pre-made options. Have any of you Leica M5 users had experience with one of those?</p>

<p>What I would really like to know from those of you who have been faced with this dilemma yourself is, what was your prefered solution, and are you still happy with it? If not, what might you advise me to do today? Thank you all for your advise.</p>

<p> </p>

<p>I encountered the same mercury battery issue with a Leicaflex SL which I sent to Don Goldberg (DAG). We talked and I had him install a modern battery and recalibrate the meter. Everything worked fine, and I was getting about a year on the battery we chose. I no longer have the camera, so can't tell you which one we chose. My experience with the recalibration was obviously a good one. I had a less successful experience with a Wein cell in another camera....it gave up the ghost in short order.</p>

<p>Standard 671 hearing aid batteries and home made adapters for all my Nikon F meter heads and a pair of Nikkormats and some other stuff that uses 625 batteries. Buy em at Costco, a card of 30 lasts a long time and costs around $12.</p>

<p>BTW, mercury cells leak and corrode stuff as well.</p>

 

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<p>Standard 671 hearing aid batteries and home made adapters….</p>

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<p>What kind of an adapter did you make, Bob?</p>

<p>Stephen,</p>

<p>What kind of meter accuracy and consistency, (+ or - exposures fluctuation), did you get throughout the life of the battery? Were exposure readings accurate enough for transparency film?</p>

<p>One like this, (several actually) that holds a 671 hearing aid battery so you can stack two of them in a FTN meter head.</p><div></div>

<p>Hearing aid zinc air cells have more air holes than the Wein cells. Some users have had some success in covering some of the holes and extending the life of the cell. It takes very little air to make the cell work once it is activated. Using typical zinc air cells I can get nearly a year from my Rollei 35 (battery compartment is a chamber inside the camera). My worst battery life is in my Konica Auto Reflex T3N where a zinc air cell lasts about one to two months. If you are planning to keep the M5 for a long time, the conversion to a 1.5 silver cell would make sense. BTW, even if you find mercury cells elsewhere in the world, it might not be legal to import them.</p>

<p>I think you could import them, problem being you would probably have to establish an EPA approved recycling plant for them.</p>

<p>Robert - meter accuracy was right on the button and worked fine for slides - I changed the battery yearly, needing it or not as my insurance.. BTW, if I am shooting slides (pretty infrequent these days), and using a camera's meter, I typically slightly underexpose - about 1/3 stop or so), more often than not I rely on my incident meter or the Sunny 16 rule if it is bright and sunny out.</p>

<p>I've used the CRIS MR-9 adapter for years in M5, CL, Yashica Lynx 14 and a Spotmatic F. LIfe fron the S76 used with the adapter is excellent and they are available everywhere. No meter problems at all, just like using the original PX625 mercury battery .he only downside is that occasionally I'll have a $30 adapter running a $20 camera, but you can move it from camera to camera.</p>

<p>After many of the above mentioned solutions, I have come to the conclusion that known <strong>full</strong> current to the meter circuit recalibrated to match a known exposure level is the best solution. The partial and unstable current provided by most PX13 substitutes is not reliable, stable nor acceptable. I fill the meter in question with <strong>new</strong> PX625 alkaline batteries and adjust the meter (ISO) to match my Minolta Autometer IV. The alkalines deliver a respectable and functional lifespan of dependable full power before they start to roll off their voltage. If in doubt, I use new alkalines. Some meters with low current draw may work well with Wein cells or silver oxides and a diode adapter but I always have doubts. The character of the meter needle never seems as robust and positive with anything other than full current. Without adaquate amperage delivery to satisfy the demands of many mercury designed meters, it's as if they are on chemo therapy. Give me new alkalines and I'll be happy.</p>

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<p>"BTW, even if you find mercury cells elsewhere in the world, it might not be legal to import them."</p>

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<p>Good point Mike.</p>

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<p>One like this, (several actually) that holds a 671 hearing aid battery so you can stack two of them in a FTN meter head.</p>

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<p>Thanks for the pictures, Bob, but your work is way beyond my skill level. :-)</p>

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<p>Robert - meter accuracy was right on the button and worked fine for slides</p>

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<p>Stephen, do you remember if it was a silver battery of some type and did it fit in the chamber without putting an "O" ring or something like that around it?</p>

<p>Not sure about the Leica battery compartment, but the smaller 675 zinc air button cells have worked in several of my cameras without any modification: Canon FTbn, Canonet GIII QL17, Olympus OM-1, others. Spring pressure from the leaf or coil springs in the battery compartments was enough to ensure reliable contact.</p>

<p>If the spring pressure seems inadequate try gently prying up the leaf spring or stretching out the coil - but be careful not to stress them too much or solder joints might break. Or just use a conductive metal shim - a bit of copper would do.</p>

<p>Those 675 zinc air hearing aid batteries lasted around 3-9 months, depending on the camera. They will leaky more readily due to the air vents, so check them often. Even when they leaked it wasn't as corrosive as leaky mercury or alkalines. It was a clear goo with a consistency similar to corn syrup and cleaned up easily. But I never let it go for long, so I don't know about long term potential for damage.</p>

<p>"No meter problems at all, just like using the original PX625 mercury battery…" </p>

<p>Gerry, how was the meter accuracy over time as the battery aged? Did it stay pretty much consistent? How long did the meter last?</p>

<p> </p>

<p>Silver oxide batteries have a flat voltage output, just like a mercury, then the drop off is just as fast. Alkalines drop from day one, even in the package. A very long shallow slope that messes up the accuracy of some meters, notably the circuit design used by Nikon in their older meters in the F and Nikkormats.</p>

<p>I would recommend getting calibrated for a silver oxide battery, since as Bob just noted, they have very stable voltage. It is getting hard to source silver oxide batteries in the "625" shape, but they are out there. Or, you could use a "button" silver oxide battery with a mechanical adapter.<br>

Don't get calibrated for an alkaline 625 battery, as they have wildly unstable voltage, pretty much useless as a meter battery.<br>

The zinc-air batteries, of which the Wein cell is just a variant, do have the devastating downside of causing horrific corrosion if you leave them in the camera and they die. But they have a very stable battery.<br>

The CRIS product is an adapter with a Schottky diode in it to drop the voltage of the silver oxide battery you put in it to about the voltage of a mercury (properly zinc/mercuric oxide) battery. But this isn't really quite as accurate as recalibrating the meter to take a silver oxide battery "straight".</p>

 

<p>Bob - mine was a silver battery but I don't remember it having an "O" ring...maybe DAG put an insert into the chamber. Same topic, different camera...I recently encountered a similar issue when I picked up a near mint Yashica GS. Although I ordered a spacer kit which provides an exact fit for a silver replacement cell, I've been using two batteries (which provided 1/2 total needed voltage each) I had on hand (stacked) in series, surrounded by a homemade paper tube for insulation. So far, exposures have been right on. I agree with others for the Leica though, because the solution is not only simple but also reliable...have Sherry recalibrate your meter for a modern Silver battery, in the meantime you can experiment with an option or two mentioned above.</p>

<p>When DAG cleans and "upgrades" an MR4 meter or equivalent he installs and recommends the PX 625A which is the alkaline equivalent of the PX-625 original. from personal experience it works perfectly, is a direct physical replacement (no adapters required) and is totally succesful. Huge amounts of print and web space have been devoted to a proper replacement. Don's comment is that he's been doing this replacement for 20 years with no issues. give it a try before you go nuts with Wein cells. </p>

<p> I used to shoot the Minolta SRT camera's that originally used the mercury battery. My fix for it was to just use the LR44 battery and to recalibrate the meter. The battery is smaller then the original battery and I found two ways to solve this problem. The first was to go to the hardward store and buy a rubber o-ring and just inserted the battery with o-ring into the compartment. Since there are many o-rings available I took my camera into the store and sorted through the different ones until I found a o-ring of suitable size. It was a rather thin o-ring. However later I lost the o-ring and just put the smaller battery in the compartment and found that it still made a solid contact and when the little cap was on it did not move around. It just was not exactly centered. Made no difference at all as the contact points were still within range. . I gave the camera to my son-in-law and he still used the camera that way without the o-ring adapter.<br>

If I had an M5 I would have the camera person you mentioned re-calibrate the camera for the LR44 or equivalent battery. Then I would try the battery with and without the o-ring and see what makes you happy. Remember the o-ring needs to be thinner then the battery or else the cap will not make proper contact. For my experience the adapter was more trouble then it was worth when I found that the smaller battery in a bigger compartment still worked without a glitch. <br>

The calibration cannot be overlooked however as the LR44 is of a higher voltage then the old mercury battery. As mercury is now considered a hazardous material and illegal I would not consider trying to find one.</p>

<p>To my mind the cleanest option is to have the meter calibrated to accept the 1.55 volts of the SR44 silver oxide cell (and <em>never</em> use the LR44 alkaline one). For my Canon FTb, though, because re-calibration was not available, I chose to buy an adapter from a Dutchman that was similar to the CRIS one but cost a good deal less. Maybe he, Frans de Gruijter, still makes and sells them.</p>

<p>Case in point. I have an old Gossen Lunasix 3 hand held meter. The old gray model I think identical to the LunaPro. It requires 2 PX13 mercury batteries and has a battery check slide switch on the back. With mercury cells the needle should fall within the red "battery check" range indicating proper voltage. <br>

With alkaline cells installed I adjust the trim screw on the back so the needle reads exactly #18 on the meter range. This is slightly beyond the high end of the red battery check range. I have also added instructions near the battery compartment door indicating this. The meeter works perfectly and provides reasonably long and stable life at the the #18 battery check position. And I can recheck it any time I want. No roll-off of voltage from day one. Alkalines have been in this meter over 1 year without the needle moving from the #18 battery check position. Needless to say, I swapped them for new anyway.<br>

I own lots of meters, new and old, and have tried <strong>all</strong> the methods to fix the "mercury issue" mentioned in this thread. Alkalines are cheap, easy to get, the correct dimmensions, and provide the electrical current to have the needle snap into a confident reading instead of meekly crawl to a stopping point that provides little confidence. <br>

Is it the perfect solution? No! But it is the best I've found.<br>

PK</p>

<p>When this first happened, there was a lot of discussion about it on the web, and a Google should reveal quite a few.</p>

<p>There are, however, a number of cameras that use "bridge" circuits for which the 1.5v batteries work: see an discussion at http://www.aohc.it/batte.htm for Pentax, which largely holds for Prakticas as well. Leica? maybe not.</p>

<p>There are links to a number of other solutions at http://www.kyphoto.com/classics/mercurybattery.html -I didn't look to see how many of their links are still good.</p>

<p>Thanks to <em><strong>John Shriver</strong></em> for spending the time to type everything I would have typed...</p>