WS 25 Battery change on MechaQuartz IWC Caliber 631 R397 (SR726SW)
Watch: IWC DaVinci Chronograph 30 mm Ladies' with snap-on case back


My daughter was pretty upset that Mum was late to pick her up from school this week (May 2006) because Mum did not notice that the IWC MechaQuartz was jumping in 4 seconds intervals indicating a battery that is going to be dead soon. The watch was running virtually at half speed and lost 30 minutes in one hour. Time to replace the battery. I thought, OK, that is an easy one, I have changed this battery a couple of times. After checking my Batteries list (where I also keep instructions on what to observe for each watch). However, no information there. And I could not really remember what I used in the past. I pulled the HOROTEC Case Crab yet it turned out it was not suitable because the case back opening gap  was exactly at 9 o'clock and thus opposite the crown (not a problem for the HOROTEC) and the pushers. But I feared that the pushers might have pressed too hard by the case crab so I looked at the gap again. The gap is quite narrow, thus I figured a watchmaker's case opener blade would be a good option. This time I was very disciplined and photographed all stages patiently, moving the tripod in front of the watch, adjusting the lights, used the self-timer for the "action shots" and I hope it was worth all that effort. These reports are a lot easier to do if you have a photographer at hand that can do the shooting while you concentrate on the watch work.
I hope that this article will be viewed a couple of times and hopefully helps you to change your batteries quickly and safely and last but not least, for a lot less money.

Reto Castellazzi, May 2006

Materials needed (bold required)

All the tools are also available from our online shop PMWC (will open new window to online shop). Have a look at the PMWC Starter Kit that contains most items beginning watchmakers (I call myself watch tinkerer, that is a fair description of my skills) need to start.

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The Start - well, almost

The unblocked View of the Front

"Froggie" was a nice companion during the watch work

Opening the bracelet for easier access to the case back opening groove

The Case Opener knife at work (blunt blade)

The open watch, the case back, the new battery

The IWC MechaQuartz Caliber 631 close up

Battery removed

Using the insulated RUBIS tweezers to press down the battery

Using a Q-tip to remove soft residues on the case

Using a toothpick to remove harder residues (crust that naturally builds up under the edges of the case back)

After the new battery is inserted and before the case back is closed, CHECK whether the watch is running

The End