Leica M5: Using 1.5v silver oxide batteries

[mhoskin]

You can also use a 1.4 volt zinc/air battery (#675 for hearing aids) with a simple home-made adapter: http://rick_oleson.tripod.com/index-111.html[/QUOTE]

Thanks for the link. I just did this for my new-to-me M5 and it works like a charm. The readings agree with my handheld spot meter. If there's one small detriment to the 12AWG hack it is that the thickness of the wire rim exceeds the thickness of the original battery. This means the battery cap won't screw in quite as far as you'd like. If I had a lot of time on my hands I'd consider using 14AWG wire and after molding it around the battery would flatten it down some with a hammer. You certainly can't beat the price though.

-Mark

 

[raytoei@gmail.com]

the m5 battery cover is slightly different from other PX625 covers. i tried a
china adapter supposedly thinner than the C.R.I.S adpter and still the cover
wouldn't close properly. In the end, i resorted to the alkaline version of the
px625 which is 1.5v. I found it to be accurate and I have tested the metering
several times in the past 2 months against my VC II light meter, it is still
accurate (!). I bought this m5 from a german merchant who left it sleeping in
a case for 25 years, so i am not sure if he made the mod to the m5 or not.


sorry to confuse the issue further.

raytoei

 

[KoNickon]

Not sure what the difficulty is in fitting the smaller battery into the M5 compartment. I happen to have some 675 mercury cells and they fit fine -- the cap just screws in farther (fortunately it has enough threading to do this). A silver oxide cell (44 or 357) has similar dimensions and similar discharge curve, and will work fine -- just set the film speed one stop slower. You can also buy 675 zinc-air hearing aid batteries, which are about the same size as the 44 or 357, and are the correct voltage. Very inexpensive too.

 

[Mark C]

I see this is an older thread that got resurrected, but it is good timing for me. I recently got an M5 outfit, mostly for the lenses, and am deciding whether to sell of the body (it needs service), or have it fixed up for myself.

I'm leaning toward keeping it, but am confused by the battery decision. Is there any reason not to have it calibrated for 1.5 volt batteries? I believe that was what Leitz was doing a few years back.

As to the battery fit just mentioned, unless I missed something, that was in reference to the battery adapter, not the 1.5 volt batteries themselves. If there is an adapter that works, I'd like to know, otherwise I will probably have it adjusted to use 1.5 volt batteries directly.

Thanks for any input.

 

[el fotografo]

I have two M5's and both were recalibrated for 1.5V alkaline batteries; one by DAG and the other by Sherry during a CLA.
I grew tired of replacing air cells every month or so.
I also have a nice Leicaflex that had a CLA and recalibrated meter by DAG when I bought it. (The CLA cost more than the camera..)

I've shot rolls of film with both M5's and have not experienced misreadings or other issues as a result. The only issue I have is the meter is difficult to see in low light.
I also agree with Varta batteries; both came back with them installed. The meter in the M5 is one of its best features.

 

[colyn]

I would never have the meter recalibrated to the alkaline cell. Because of the steep voltage drop once a load is placed on it accuracy is lost. I've used the schottky diode method for years without any accuracy issues. Once installed you place a rubber "O" ring with a 5/8 inch outside diameter and a 7/16 inch inside diameter in the battery chamber and add a 357 silver oxide cell and you end up with 1.35v..

The 386 silver oxide cell used with the CRIS adapter has a poor voltage curve compared with the 357 which is nearly identical to the original mercury cell..

The wein cells or zinc-air cells are good alternatives except for their short life span..

 

[Mark C]

Is there no silver oxide battery that works with the existing battery compartment? How is the diode method different than recalibrating for 1.5V, or isn't the 357 1.5V?

 

[colyn]

Is there no silver oxide battery that works with the existing battery compartment? How is the diode method different than recalibrating for 1.5V, or isn't the 357 1.5V?

There once was a 625 silver oxide cell but I haven't seen one in several years.

The diode method drops the 1.55v through voltage .2v to 1.35v which is the proper voltage. Reclibration to 1.5v simply modifies the meter to give proper voltage at 1.5v but alkaline cells start to lose voltage once a load is placed on it whereas mercury and silver oxide holds its voltage throughout then drops off at the end of its life..

To give you an idea I have copy/pasted the below information from my page for modifiying the Weston Ranger 9 meter which requires 2 diodes but the same except for voltage would apply to other mercury powered cameras/meters. Camera meters usually use 1 cell instead of the 2 for this meter and don't have the same ratings so the load will be different. Most camera meters have a lower load..

The Weston Ranger 9 meter's current rating is approx. 50µA-1875µA or just under 2mA (1,000µA=1mA)

Forward voltage is approx. 3.0v with the 2 schottky diodes installed and drops to 2.7-2.8v when a load (light measurement) is put on the meter. At low to medium light readings, measured voltage is approx. 2.6-2.8v and drops to 2.5v at heavy load. When I subject the meter to light too bright to measure, voltage drops to 2.4v.

I get identical readings with a Ranger 9 with the original mercury px14 2.7v battery installed in a non-modified meter.

Forward load voltage of 2.5-2.8v is correct for the this meter and will give accurate readings, therefore this modification is the best alternative since it gives identical readings to the original battery.

Calibrating your meter to use 2ea. 625 1.5v alkaline cells give approx. 3.3v and drops to 2.9-3.0v under load which is slightly too much voltage for accurate readings. Once you burn off approx. 0.3v, your meter will be accurate till voltage drops another 0.5v. The alkaline cell looses voltage as soon as you put a load on the meter and continues to drop. Alkaline has a very sharp voltage curve and only gives you accuracy through only about 10% of its life span...not very cost worthy..

 

[jmcd]

The alkaline batteries will work fine for many months in the M5. As the battery discharges it will get to the point where the meter calls for extra exposure, up to a stop—still juice left, but not enough to be totally accurate. This is when I change my battery.