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329-to-388 converter

Converts from Diameter: 7.9 mm. Height: 3.1 mm.

to Diameter: 8.9 mm. Height: 3.3 mm.

Price: 7.50 each. 7.30 each if you buy two or more. P&P included.

Also known as: SSIH 9910, Varta 503, Bulova 211, Mallory 10R10, Accucell-2.

We supply this 329-to-388 converter, a small plastic spacer that bulks out the 329, SR730SW or SR731SW to be the same size as the withdrawn 388 cell. This reusable converter only changes the dimensions and does not modify the voltage (unlike our voltage reducing 388-Adapter kit).

The 388 was a mercuric oxide cell of nearly the same dimension as a 329, SR730SW or SR731SW. The 388 mercury cells are no longer manufactured because of their toxicity and environmental unfriendliness. Although the electrical properties are slightly different, if your requirement is to replace a 388, you have little option but to try a silver oxide 329, SR730SW or SR731SW in its place. 

388 batteries were used to power 221 / 2210 models of the Accutron tuning fork watches.

To replace a 388 cell, where 1.55 volts is acceptable, we recommend you purchase two items from us, a 329 cell and a 329-to-388 converter. When the battery runs out, you need replace only the 329 cell. The plastic spacer can be reused.

A correctly tuned Accutron will not run fast with a silver oxide battery, but a slightly 'off' Accutron can gain time with the 1.5V battery but be fine with the old 1.35V. This is a process called double indexing whereby the slightly greater amplitude of the tuning fork means it can occasionally take two clicks forward when it should only take one, hence gaining time. If your watch gains time you can consider an expensive service of your watch or simply use our voltage reducing 388-Adapter instead of this 329-to-388 converter.

A voltage reducing 388-Adapter kit is the "Rolls Royce" solution to problem of the discontinued Mercuric Oxide 388. Our 388 Adapter has the outer dimensions of the 388 mercury cell but takes the inexpensive and easily obtained silver oxide 396 cell. Buried within the 388 Adapter are micro electronics that drop the voltage from the 1.55 Volts put out by the silver oxide cell to the 1.35 Volts that your watch was designed for.

For more background information, find out about mercury replacement batteries.

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