Possible PX625 battery replacement?

[dave_gesell]

<p>I was recently given a beautiful Konica Auto S2. The foam seals are a little gummy but otherwise it's in astonishing condition, and I've fallen in love with it already. Of course the meter uses the discontinued PX625 Mercury cell, and in trying to find a suitable battery, I figured I'd try The Source (formerly Radio Shack), and found this:</p>

<p>http://www.thesource.ca/estore/product.aspx?language=en-CA&catalog=Online&category=Watch+Calc+Batteries&product=2300465</p>

<p>The description states it's a 1.35v cell, but the packaging, which doesn't say EXP625 anywhere on it, says 1.5v. Hopefully I can get to a store after work tonight and check it out. Anybody tried these batteries?</p>

[glenn_mabbutt]

<p>I have an Auto S2 and it's one of my favourites - awesome lens (rumoured to be a Summacron design made after Leica's original patents expired).</p>

<p>I haven't tried this particular battery. It's my understanding normally "standard" alkaline batteries don't come in 1.35 V, and I'm not sure if the Auto S2 has a circuit to correct for the voltage difference.</p>

<p>It's usually recommended to use a zinc-air hearing aid battery in cameras that were made for the 625 mercury batteries - they're cheaply available at most drug stores because older hearing aid models also need 1.35 V batteries. The downside is they don't last a terribly long time in a camera, but being cheap it's a minor issue.</p>

<p>The other option is to use a "Wein cell" battery, available from better photo stores or online. It is also zinc-air, but lasts somewhat longer, and has a removable metal ring that better emulates the shape of the original 625 (the hearing aid batteries are a bit smaller, but it's not usually an issue - some tin foil can be used around the battery in a pinch if it's a problem).</p>

<p>Actually, I bought a Wein cell first, but it ended up being dead - so I salvaged the removable ring and use it on the hearing aid batteries. Works very well.</p>

[andrewg_ny]

<p>Dave, it might <em>sort of</em> work but in many cameras/meters would not be accurate. The issue is that mercury batteries offered a very flat voltage curve during their lifespan where it would maintain a consistent 1.35V during its life and then very quickly drop off at the end. Vintage lightmeters often took advantage of this characteristic for simplicity/cost and didn't have their own voltage regulation. There are a few exceptions like some Pentax Spotmatics that included a bridge circuit but many meters did not. </p>

<p>Alkaline batteries unfortunately gradually lose voltage over time--usually starting ~1.5-1.6V, so if the meter is voltage-sensitive (like it probably is in that Auto S2) the meter will be inaccurate and change during the battery's lifespan.</p>

<p>Silver Oxide (instead of Alkaline) batteries have a performance curve more like mercury but have a higher voltage rating. Sometimes a camera can be modified or re-calibrated to work with the higher voltage, and there are some rather pricey adapters that can do this in some cases without modifying the camera.</p>

<p>Zinc-Air/Wein cells have performance characteristics and voltage that is appropriate but have the disadvantage of greater cost and once you start using it (once opened and exposed to air) they will only last a few months. Reasonable if you're using it frequently but not ideal if you're powering a fleet of less frequently used cameras/meters.</p>

<p>I imagine if you search in this forum for 'mercury' and/or 'batteries' you'll find many, many threads discussing this further.</p>

[daverhaas]

<p>I haven't tried that brand in particular, but I have tried some other 1.35 volt that claimed to be a replacement for the 625 Mercury and they did not work. (I have two beautiful TC's) -<br>

There was a guy on the web a couple of years ago that would either do the conversion for you or give you detailed instructions on how to do the conversion. </p>

<p>If I remember correctly there was a little bit of wiring and connecting that had to be done to get it to work properly.</p>

<p>Dave</p>

 

[dave_gesell]

<p>Thanks for the responses. I was aware of the alternatives, but I was hoping against hope that this would be a easy solution. Andrew, thanks also for the reminder about Alkalines voltage curve. That had totally slipped my mind. I'm about to order some film from Freestyle, and they have the Weincell at a good price, so I'll add a couple to the order. I'll likely pick up one of the batteries I linked to. Maybe it's voltage will stay consistent long enough to cover me until the Weincell arrives.</p>

[tomscott]

<p>I would have to say that, since the packaging says 1.5V, that it is probably 1.5V. My quess is that whoever did the add made a mistake and put in 1.35V. It is unlikely that the manufacturer made a mistake and misprinted the package.</p>

[dave_gesell]

<p>Tom, I agree that it's unlikely that kind of mistake would be made in the packaging. The error, if any, would be on the website, either the copy or the picture. There's a location in my neighbourhood, and it's on my way home, so no harm to stop in.</p>

[Mike Gammill]

With most cameras the alkaline cell will initially lead to underexposure. For a while the voltage will hover around a value to

give correct exposure. As voltage drops more overexposure will result.

[james_kennedy9]

<p>this works well but is overpriced.</p>

<p>http://www.criscam.com/mercury_battery_adapters.php</p>

[dave_gesell]

<p>I stopped at The Source on the way home and it turns out that the copy on the site is wrong. The battery is in fact 1.5v, so as I mentioned previously, I'll add a couple Weincells to my next Freestyle order, and when the first one dies, I'll try to hack it to use the appropriate ZA hearing aid battery. Thanks.</p>

[tomscott]

<p>I don't know if you've seen this but, there is a pretty good little kit to make your own adapters and it is cheaper than Wein cells and not too complicated to make. If I remember correctly I paid $9.00 for the kit to make two adapters. Email <a href="mailto:battery.adapter@orange.nl">battery.adapter@orange.nl</a></p>

[bob_sunley]

<p>For about the price of two wein cells, you can pick up a card of 30 blue tab #675 hearing aid batteries at Costco.</p>

[dave_gesell]

<p>Upon further investigation, I think I'll try, as Bob suggests, the 675 ZA batteries and try making an adapter as detailed <a href="http://rick_oleson.tripod.com/index-111.html">here</a>. Since the Auto S2 has an edge contact I'll just have to scrounge some single strand 12 gauge wire. I've got a long weekend coming up, so I have time to tinker. </p>

[bob_miller4]

<p>To fit snugly in most cameras, the 675 may only need an O-ring.</p>

[tomscott]

<p>To the best of my recollection, the 675 battery and o-ring trick will not work in the Konica Auto S2 because of the side contact in the battery chamber. This is why you must have some sort of metallic o-ring or adapter for the battery to sit in. I believe the one Jon Goodman sells on ebay will work for this purpose.</p>

[dave_gesell]

<p>Tom, the DIY adapter I linked to mentions that for side contact battery chambers, you should use 12 gauge single strand (solid) wire, and strip the insulation off. For chambers that use the cap as a contact, he recommends you use 18 gauge wire, leaving the insulation intact.</p>

[tomscott]

<p>You are right Dave, I didn't see your last post before I posted. That seems to be about the most economic fix for the Auto S2. If you look here: <a href="http://www.butkus.org/chinon/batt-adapt-us.pdf">http://www.butkus.org/chinon/batt-adapt-us.pdf</a> you will find some more options including the DIY adapters I spoke of earlier. They are on the bottom of Pg. 11.</p>

 

[dave_gesell]

<p>Success! And definitely economic. I stopped into a hardware store and picked up a foot of 12 gauge wire at 29¢, a drugstore for an 8 pack of 675 Z-A batteries at $8.99, and a bit of rooting around at home to find a suitable cylinder to wrap the wire around (a AAA battery), and I now have an Auto S2 with an operating meter that pretty closely agrees with the meter in my DSLR.<br>

Thanks for all the links and suggestions.</p>