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Thread: Zinc-Air cells.

  1. #11

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    Quote Originally Posted by ic-racer View Post
    I use a lot of zinc cells but have never done this. Does that make them last longer?
    "....3 of the four airholes are blocked off by using gold nailpolish (just in case it's conductive) to glue three 1/16"~ squares of Al foil over the airholes of each cell. The needle goes to the far end of the red block on test, I replace the cells when it falls to the near end of the red block. They last 2+ years."

  2. #12
    AgX
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    Altered hole area was one of the Wein cells alterations to standard Zn-Air cells.

  3. #13

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    Quote Originally Posted by AgX View Post
    Altered hole area was one of the Wein cells alterations to standard Zn-Air cells.
    Yes, but: The Wein cells are far more expensive than 675 hearing aid cells - two Wein cells cost more than 8 675s at the local stores. Wein cells have two holes, and last at best a few months. There's no reason why you can't block off one hole, though.

  4. #14

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    Something I forgot to mention is that the 675s are slightly thinner than the original cells. I use a roughly .030" x 5/8" disc of copper between the cells in the Gossen meter to make up for this.

  5. #15

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    E.

    I have never tried blocking the holes, but it sounds like it is working for you. I use the same hearing aid battery in my OM-1's and it works fine for a few months. I change them often since they are very cheap. I use a V shaped piece of paperclip to take up space, and an o-ring to center the cell. The paperclip fits snugly in the battery cover so it stays in there while changing the battery. Thanks for sharing.

    Chris

  6. #16
    Newt_on_Swings's Avatar
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    Wouldn't blocking off the holes on a camera that you use the meter frequently on drain it so that it would be inaccurate until you let it rest and have it recharge through a slow reaction with air? I remember I had tried to use these zinc cells, with all holes uncovered in a camera that was very dependent on batteries, an om-40 and it frequently ran out of juice and had the shutter lock up when it drained only to come back after sitting for a bit. I only used the zinc ones that one time as I got them on sale at Walgreens. I went back to silver oxide batteries after that.

  7. #17
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    Interesting. Just the other day I put two new zinc-air cells in my Nikon FTN meter and it still wouldn't work. I checked the voltage and one was at about 0.3 volts. The other was OK. Guess some of them don't always work right even when new. I had never had this happen before.
    We are off to Japan in less than a week, and I have decided to take a small multi-meter just so I know if the cells are performing properly. Kind of a pain, but better than not knowing if the problem is the cells or the meter.
    Bruce

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  8. #18

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    Zinc-Air Cell Operation

    During discharge, a mass of zinc particles forms a porous anode, which is saturated with an electrolyte. Oxygen from the air reacts at the cathode and forms hydroxyl ions which migrate into the zinc paste and form zincate (Zn(OH)2−4), releasing electrons to travel to the cathode. The zincate decays into zinc oxide and water returns to the electrolyte. The water and hydroxyl from the anode are recycled at the cathode, so the water is not consumed. The reactions produce a theoretical 1.65 volts, but this is reduced to 1.35–1.4 V in available cells.

    Zinc–air batteries have some properties of fuel cells as well as batteries: the zinc is the fuel, the reaction rate can be controlled by varying the air flow, and oxidized zinc/electrolyte paste can be replaced with fresh paste.

    The cell requires OXYGEN to operate, think fuel cell, and in the closed and sometimes sealed space in cameras, there is no available oxygen so the cell can not deliver the current (milliamps) required to operate the meter in bright light conditions, the voltage drops under the load and the meter is unable to get the current needed for proper reading, but the cell may supply enough current under lower light. Sealing the holes starves the cell of oxygen reducing the power available


    Zinc-air batteries can be used to replace now discontinued 1.35 V mercury batteries (although with a significantly shorter operating life), which in the 1970s through 1980s were commonly used in photo cameras.
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  9. #19

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    Quote Originally Posted by Newt_on_Swings View Post
    Wouldn't blocking off the holes on a camera that you use the meter frequently on drain it so that it would be inaccurate until you let it rest and have it recharge through a slow reaction with air? I remember I had tried to use these zinc cells, with all holes uncovered in a camera that was very dependent on batteries, an om-40 and it frequently ran out of juice and had the shutter lock up when it drained only to come back after sitting for a bit. I only used the zinc ones that one time as I got them on sale at Walgreens. I went back to silver oxide batteries after that.
    A OM-40 can use SR44 or LR44, but uses lots of current on long exposures, I use the LR44 and carry a spare set.

    The air cells won't do 100% performance immediately after activation even if all the air holes are open. The modern hearing aids normally have a low duty cycle cept in a DISCO.

    They are not wonderful on battery dependent cameras a silver cell and Shockety diode better.

    The mercury cells were not very high current anyway.

  10. #20
    AgX
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    Quote Originally Posted by Cruzingoose View Post
    The cell requires OXYGEN to operate, think fuel cell, and in the closed and sometimes sealed space in cameras, there is no available oxygen...
    I do not consider the cameras from the era we are talking about as air sealed. Furthermore many caps of battery enclosures intended for Hg-cells have got a venting hole.

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