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Discussion Starter · #1 · (Edited)
Every time I see a nice Accutron on eBay and think....yeah...I'll get that one....I read the description and it says "watch serviced and regulated to run on Accucell". I don't want to pay $35/year for a watch that runs on $17 batteries that only last 6 months. I thought the great voltage debate was settled long ago and we (ie experts/RKIs like Rob B) have determined that you can regulate a 214 movement to run fine on 394/387s batteries with no risk to the movement.

Why can't the battery industry just make a battery the same size as the 394/387s that is 1.35V or a 387 size battery that is 1.35V.

If a watch is regulated to run on an Accucell and you drop in a 394, what would happen? Does the 214 have any tolerance or self regulating ability?

:unsure:
 

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Personally, I don’t believe you will notice much of any difference unless a slight change in accuracy that should be able to be easily regulated.
 

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“Why can't the battery industry just make a battery the same size as the 394/380 that is 1.35V or a 387 size battery that is 1.35V.”

Because there is very little demand. VIntage accutrons are the only thing that use them.

As an example, about a decade or so ago when the renata 333, 751 and 44 were still being produced, Those batteries sell for ~$45 each, due to very low volume.


Sent from my iPhone using Tapatalk
 

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They don't make 1.35V watch power cells anymore because the chemistry required involves mercuric chloride, which is converted to liquid mercury in the course of the chemical reaction. This is literally the reason why those cells ceased to be manufactured. The Accucell is a substitute developed by dropping 0.2V from a 1.55V silver-oxide cell through a diode, precisely to meet the need for a 1.35V cell for those Accutrons which cannot be adequately regulated to work on 1.55V.

Now, it's a perfectly good question why a repairer wouldn't regulate an Accutron to run on 1.55V cells, if at all possible.
 

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Discussion Starter · #5 ·
Okay...I get it...but is the Accutron the ONLY thing ever invented in the history of all things in the universe that was designed to take a 387 size battery AND need 1.35V? It is technically possible to make a 1.35V battery in any size right? Other than the cost to manufacture it, it would be possible. The mercuric chloride was just a chemical they uses at the time. Could you make a silver oxide battery produce 1.35V?
 

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Things are not that simple, for reasons of electrochemistry.

Every set of substances which can be used in a battery has its own characteristic voltage. 1.55 volts is the characteristic voltage you get when you pair zinc metal with silver oxide : because zinc has a higher electrochemical potential than AgO, when you put the two materials in contact, with a suitable electrolyte, the silver will be reduced to its metallic state, while the zinc is oxidized, & a potential of 1.55 V is developed.

Similarly, when you put zinc in contact with mercuric chloride, 1.35 V is developed. That potential difference is something you can't change.

Are there other combinations of materials which will give potentials of about the same value? Sure. But they may not be practical for a watch power cell. In a real electrochemical cell of this kind, the potential developed varies somewhat from beginning to end of the reaction (ie, from a fresh to an exhausted cell). The silver-oxide & mercuric-chloride chemistries were both chosen because those two particular chemistries give an especially small variation. In other words, the cell voltage remains nearly constant until it drops off suddenly at the end of the cell life. To get that effect with another chemistry, which would be easy to manufacture into a button cell, is clearly enough of a problem that no satisfactory replacement has ever been created.
 

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I believe Rob has addressed this previously. Maybe he will chime in again.
Yes indeed he will! Rather than me type a lengthy post here about it, why not have a look at my web page on phasing accutrons, which pretty much tells all you need to know. The link is: http://members.iinet.net.au/~fotoplot/accphs.htm

I agree with Dillworth, when someone says "Serviced and regulated to run on Accucell" , it means they don't understand what they are doing.

Rob
 

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Discussion Starter · #11 ·
Thx Rob. The instructions/secret sauce on how to phase a 214 to run on 1.55V batteries is "open source" and sitting on a server for the whole world to see and yet people still muck around with Accucel...amazing. If you are a competent jeweler with enough smarts and tools to work on a 214 or at least think you know what you are doing, you'd think that by now, everyone would just run with the instructions that Rob has so generously shared with the world on how to do it. An Accucell watch is a real turn-off for me. If you want to cell a watch, get it serviced so it runs on batteries that cost $1.00.
 

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Rob B deserves a ton of praise for his generosity in "open sourcing" his method for phasing tuning forks, as well as the wealth of information available on his site. Thanks Rob B, it's been an invaluable resource!
 

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Discussion Starter · #14 ·
Indeed! Thx for the battery lesson. I did not consider the chemistry behind the reaction. I sure wish more people took the time to read and understand the 214 the way Rob does.
 

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Not to provoke an argument re 1.55 and 1.35 V batteries and their usage, I just want to tell you of my experience with my 1965 214 Accutron. In its life it probably spent more hours in my sock drawer (put there when the mercury cells ran out). About two years ago I sent it off for a CLA. I asked that it be adjusted for the silver cell voltage. It came back and I found it to be not as accurate as I expected, running slow at the ragged edge of the original Bulova specification. I got used to making the occasional adjustment to satisfy myself. I don't know what prompted my next step but I sent away for five Accucells (I did like the price). Now the watch seems to be dead accurate! My reference is the Apple Watch that I have. Don't laugh, the watch uses the iPhone as a source and the Apple's time base eventually goes back to NIST in Boulder, Colorado. I can't explain it but I'll live with that.
 

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The original Bulova recommendation of setting the regulation at -2 sec/day is just right for some wear patterns, but a little slow for others, especially if you don't wear it every day. Next time you have it serviced, you might want to ask that it be set to -1 sec/day, or even near zero if you only wear it occasionally.

Cheers!
 

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Out of curiosity, the cheapest price I have found for a single Accucell battery is US$9.95 each and US$8.50 each if you buy 5 or more - Is this about right or can they be found cheaper elsewhere?
 

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Out of curiosity, the cheapest price I have found for a single Accucell battery is US$9.95 each and US$8.50 each if you buy 5 or more - Is this about right or can they be found cheaper elsewhere?
The $8.50 for five is what I did. It was cheap enough.
 

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Not to provoke an argument re 1.55 and 1.35 V batteries and their usage, I just want to tell you of my experience with my 1965 214 Accutron. In its life it probably spent more hours in my sock drawer (put there when the mercury cells ran out). About two years ago I sent it off for a CLA. I asked that it be adjusted for the silver cell voltage. It came back and I found it to be not as accurate as I expected, running slow at the ragged edge of the original Bulova specification. I got used to making the occasional adjustment to satisfy myself. I don't know what prompted my next step but I sent away for five Accucells (I did like the price). Now the watch seems to be dead accurate! My reference is the Apple Watch that I have. Don't laugh, the watch uses the iPhone as a source and the Apple's time base eventually goes back to NIST in Boulder, Colorado. I can't explain it but I'll live with that.
Back here after having to reset the hands because of DST starting on March 14. Still very accurate but I noticed something about the face and the numerals. There seems to be some 'drift' of the marks between the location of the marks if you eyeball their placement at various locations around the clock. I can only suggest inaccuracy in the 'painting' of the numerals during manufacture. From hereon I won't touch the crown and see what happens over the next 6 months..
 
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