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

Discussion in 'Leica and Rangefinders' started by robert_hooper|1, Jun 22, 2012.

  1. 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.
    Also available, are WeinCell 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.
    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?
    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 C.H.R.I.S MR-9 is one of those pre-made options. Have any of you Leica M5 users had experience with one of those?
    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.
  2. SCL


    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.
  3. 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.
    BTW, mercury cells leak and corrode stuff as well.
  4. Standard 671 hearing aid batteries and home made adapters….​
    What kind of an adapter did you make, Bob?
  5. Stephen,
    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?
  6. One like this, (several actually) that holds a 671 hearing aid battery so you can stack two of them in a FTN meter head.
  7. 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.
  8. I think you could import them, problem being you would probably have to establish an EPA approved recycling plant for them.
  9. SCL


    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.
  10. 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.
  11. After many of the above mentioned solutions, I have come to the conclusion that known full 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 new 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.
  12. "BTW, even if you find mercury cells elsewhere in the world, it might not be legal to import them."​
    Good point Mike.
  13. One like this, (several actually) that holds a 671 hearing aid battery so you can stack two of them in a FTN meter head.​
    Thanks for the pictures, Bob, but your work is way beyond my skill level. :)
  14. Robert - meter accuracy was right on the button and worked fine for slides​
    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?
  15. 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.
    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.
    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.
  16. "No meter problems at all, just like using the original PX625 mercury battery…"
    Gerry, how was the meter accuracy over time as the battery aged? Did it stay pretty much consistent? How long did the meter last?
  17. 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.
  18. 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.
    Don't get calibrated for an alkaline 625 battery, as they have wildly unstable voltage, pretty much useless as a meter battery.
    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.
    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".
  19. SCL


    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.
  20. 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.
  21. 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.
    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.
    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.
  22. 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 never 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.
  23. 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.
    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.
    I own lots of meters, new and old, and have tried all 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.
    Is it the perfect solution? No! But it is the best I've found.
  24. When this first happened, there was a lot of discussion about it on the web, and a Google should reveal quite a few.
    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.
    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.
  25. Thanks to John Shriver for spending the time to type everything I would have typed...
  26. Here is what I use in place of a mercury battery.
  27. Here is what I use in place of a mercury battery.
  28. One more try.
  29. A touch of irony here: as mercury cells are consumed, the mercury (II) is reduced to elemental mercury (which is the big hazard). A typical mercury cell has about the same mercury content as two CFL lamps. However, the average consumer is more likely to dispose of worn out or defective CFL's improperly (just tossing out in trash) than us well-informed photographers. I think they should have kept mercury cells and banned CFL's. And if you have a darkroom, a CFL can glow faintly for a short time after turning it off- possibly enough to fog faster films.
    If I can step off my soapbox here, it looks like you've got some good suggestions here. I still stand by the recommendation that the meter be recallibrated for silver oxide 1.5 volt batteries.
  30. By far the largest consumers of mercury button cells were hearing aid users, not photographers.
    Until very recently, there has been no recycling centers that will accept 24-96" long florescent bulbs either.
    Here, CFLs can be brought to Home Depot and other big box stores for recycling, long tubes are supposed to be securely wrapped and thrown in the trash where the compactor truck will crush them as it makes it's rounds. :(
  31. Good point, Bob. Around where I live, though, very few people bother to dispose of them properly. No local disposal sites are available and not many of them want to drive 20+ miles to the nearest Home Depot. Yeah, I remember that hearing aids once used mercury cells. Back when flashbulbs were widely used some photoflash batteries were mercury cells. Eventually alkaline batteries became popular (due to lower cost).
  32. Here is someone who was selling PX625 batteries until recently. The first thing to go was his email link.
    People have a point about about those darn CFL Light Bulbs. Most just throw them in the trash and a they contain Mercury plenty of Mercury. I guessing that Murcury CFR light bulbs contribute more contamination to land fills than, batteries ever did. Does anyone remember someone telling us CFL bulbs were supposed to last a lot longer? I think we've been had once again. The ones I get at Home Depot don't.
  33. I don't know how to hack a sight, but at least I thought we could crash it. Seem to be like the energizer bunny, though. It just keeps going and going.
    Have you ever seen victims of Minamata Disease, especially children?
  34. I posted this way back in 2003:
    The CRIS adapters are a little fatter and you may have trouble tightening the cover. There is a gentleman in the Netherlands that makes adapters by hand out of an actual old PX625 cell that accepts S76 or compatible silver oxide cells; the diode reduces the output voltage to 1.35 volts like the CRIS adapter. Because the adapter is actually made out of a standard PX625 cell, it fits perfectly in the M5 or SL--at least they do in my case. The adapters are $21 each (sent registered airmail) or he sells a do-it-yourself kit (for the mechanically inclined who are adept at soldering) for $10 (registered airmail). You can e-mail Mr. Frans De Gruijter at battery.adapter@wanadoo.nl. He accepts PayPal.​
    I don't know if Mr. De Gruijter is still at it, but his adapter is a perfect fit, better than the CRIS.
  35. "Gerry, how was the meter accuracy over time as the battery aged? Did it stay pretty much consistent? How long did the meter last?"
    I used silver S76 rather than alkalines. I would move the whole set up, adapter and battery, from camera to camera. My daily carry around camera was the M5 and IIRC I got well over a year with no perceptible meter fluctuations.
  36. I think it was partly scummy Chinese manufacturers using mercuric-oxide batteries inappropriately that pushed them from "controlled substance" to "banned". They were putting them into the kids shoes with the sparkly lights in the transparent soles, rather than using alkaline or silver oxide batteries. People didn't even know that throwing the shoes out was putting mercury in the waste stream.
    I saw what was happening 10 years ago, hoarded four of the PX625 batteries, have been using one in my Topcon Super D and Pentax 7s, and the other three are in a sealed bottle in my film fridge. I've got many more years before this is an issue to me. (Heck, film availability may nail me before I run out of batteries.)
    I've got a CRIS adapter, but it doesn't work in the Topcon Super D, the shape of the rather large spring in that camera shorts out the battery in the adapter. Haven't tried it in the 7s yet.
  37. Hey Paul, the zero adjust on a Gossen Luna only sets just that, the zero point. The alkalines have a very different voltage then what the Gossen's were made for, and I can guarantee you it is not accurate across the 0-20EV range they are made to work in. I say this because I Schottky diode modify them, then use adapted silver-oxide 357s, and recalibrate them at four points across the EV range. I've checked them with alkalines, they will not work without re-calibrating. And once the voltage drifts, which may take a long time, it won't be accurate anymore. The only way to check a meter (in camera or hand held) is to check it across it's useful range against a known calibrated standard (whether a camera or bench analyzer). I'm sure you are getting an accurate reading at one small range, but no likely across the whole useful range.

    Let your camera shop recalibrate the meter for silver oxides, use a simple rubber/foam adapter, it's hands down the best solution.
  38. Aileen:
    Here are the results of several comparison tests with known accurate meters. The meters used are Gossen LunaPro SBC and Gossen DigiFlash. I Have others but these were handy.
    At 1EV the alkaline filled LunaSix was .5 EV lower than SBC and .33 EV lower than Digiflash
    At 7EV the alkaline filled LunaSix was .3 EV lower than SBC and .25 EV lower than Digiflash
    At 11EV the LunaSix was one sixth EV lowere than SBC and matched the digiflash.
    At 14EV all meters matched.
    These measurments were not cherry picked from many tests. They were all objective and done rapidly. I did not use scientific methodology but I believe them to be reasonably accurate. The meter needle of the SBC allows visual fractions of each stop while the Digiflash indicates when it is at the edge of each 1/3rd stop reading. Some interpretation of the change point was necessary with the digiflash.
    We have all compared meters to each other and understand the frustration and confusion it can bring. To have a maximum varience of .5 stop at 1EV light level I consider to be within acceptable tolerance. Everyone is so concerned about the alkaline voltage roll off and so am I. But it is eliminated by using alkalines before they roll off. Silver Oxides have a much flatter curve, but don't fit. So I use more Alkalines than I would Silver oxides. No big deal. They are cheap and available with no adapters or internal modifications. And the non roll-off lifespan is fairly decent.
    If a better option comes along, I'll use it, but I have yet to find one. I also invite everyone to compare their own meters at 1 EV and see what they get. It's often not pretty.
  39. Hey Paul, the zero adjust on a Gossen Luna only sets just that, the zero point.​
    I did the same adjustment to my Lunasix as Paul did and it seems accurate. Whilst the adjustment does change the zero point, it also shifts the full range of the meter so adjusting it for the battery check position which is also in the same area as normal daylight range should make it accurate in this range. I have yet to check it in low light though.
  40. I don't disagree with what you're seeing. Only that the alkalines will roll off, consistently and gradually, taking your calibration with them. I just don't see the point in using them since a 357 silver oxide costs $2.56 at the corner drug store, and all you need is a small piece of 1/16" foam or a short piece of 1/2" ID vinyl tubing (any hardware store has this) to make them fit into the battery area (ok, and bend the spring tab on the screw cap up a little more). Then, you can do your zero adjust and know it won't change.

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