Please excuse me if you are aware of the tech info/history shared below. I want to write to those whom may not have your knowledge.
I started collecting vintage Accutrons about 13 years ago and stopped when I felt my collection was nearly complete. My last vintage Accutron purchase was about 5 years ago. When I was heavily buying, selling and swapping, a standard model 344 battery was recommended, installed by most techs at the time, and have worked perfectly in my 218 movements for years -- without any movement alteration unless basic service was needed.
The 214 movement is a completely different story, of course. Once the US government banned mercury-oxide batteries decades ago, the silver-oxide model 287S became the go-to replacement if your watchmaker couldn't get their hands on imported originals. The 287S is a higher voltage cell (1.55 volts vs the original's 1.33 to 1.35 volts) and if used, a timing adjustment might be needed or more severely, a movement diode mod if you have an extra fast running "over-active" movement. When I was collecting, the 214s I received had past adjustments/mods for the 287S or didn't need it. Some technicians were/are against the diode mod, but what was one supposed to do at the time?
It looks like new and legal silver-oxide 1.33 to 1.35 volt cells are now on the market and are perfect for non-altered 214s. If I had the bucks, I would install these new batteries and de-mod/re-tune my 214 movements, allowing them to run as designed. There is a claim by at least one seller that these new $10.00 to $15.00 cells work with 218s as well. Based on my experience, I would just pop in a $1.00 344 and time the movement.
I am hoping someone else with 218 experience will chime in, too. In the meantime, here are a couple models I pulled out from the watch case shown above.
Falstaff wrote:A superb collection of Accutrons! How have you dealt with the battery issue - have you converted them or are you using the recently introduced semi-original battery with the 6 month run time? Still trying to decide which approach to take with my '76 218.