January 2023

Quartz watches with a 10 year battery life, ronda 762

ronda harley 762 movement, 10 years of battery live on a normal 1.5V button cell battery (v364), the movement itself costs about 10 USD

A quartz movement that ticks every second is a real waste of battery power. Most quartz watches made today have a seconds hand and a low end movement with a small v277 battery. These types of movements are made in china at a very low price and they are put into all kinds of watches no matter the size. Even watches with large dials have such tiny movements with a tiny battery. These watches work, but the battery will last at most two years. Usually you will have to get a new battery every year. A lot of people throw their watches away when the battery is dead and just buy a new watch. It's a real waste but they do it because getting a watch shop to replace the battery costs maybe 10$ while a new fashion watch with battery is not much more expensive.

Technically it would be easy to make watches with a longer battery life:

Use the available space for a larger battery: There are watches that have large 1.5V button cell batteries or even CR2016 lithium batteries. Watches with CR2016 batteries will last about 5 years even with the seconds hand moving every second.
Get rid of the seconds hand and make the movement run the step motor less frequently: The ronda 762 movement does this and you get a 10 year battery life.

Almost nobody looks at the seconds hand and a seconds hand might actually cause some confusion in low light conditions. By mistake you may read the wrong time while mixing up the minute hand and the seconds hand.

The ronda 762 movement moves the step motor every 20 seconds. Your hear a tick every 20 seconds if it's very quiet and you hold the movement to your ear. In theory it should therefore last 20 times longer than a normal quartz watch ticking every second but in practice there is also an ageing effect to the battery itself. Watches with a ronda 762 movement require about every 10 years a new battery. The ronda 762 is a swiss movement assembled in China. It takes a v364 battery. The v364 battery has the same diameter as a v277 but the height is 0.5mm less. You can install a v277 if you bend the bracket that holds the battery but I would recommend to use an original varta v364 or a renata 364.

Stuhrling pocket watch with a ronda 762 movement. This specific watch has already been running for 8 years on the original battery

Stuhrling pocket watch front, this watch moves the minutes hand by 1/3 of a minutes every 20sec

If you buy a watch that has only two hands, then don't assume that it will always have this kind of movement that ticks only every 20 seconds. Most of the cheaper watches just have the exact same movement as watches with a seconds hand. They just don't assemble the seconds hand. You can however clearly see if it is such an energy saving movement. The sudden movement of the minute hand every 20sec is noticable. If the minute hand advances smoothly (in invisibly small amounts every second) then it's the wrong watch.

At online shops, you can check the specifications. You want either a large battery or a ronda 762 movement. If it says just "quartz movement" then it's usually the cheapest standard quartz movement with a tiny battery and the motor moving every second, but you could ask the seller to be sure.

Here are some other watches with this ronda 762 movement. It's fantastic to have a quartz watch that runs for 10 years on the same battery!

Stuhrling writst watch with a ronda 762 movement

Jacques Reboul writst watch with a ronda 762 movement

Update: 2023-02-26:

I had an old Timex Quartz pocket watch. The movement had a mechanical defect. I decided to convert this watch by replacing the movement with a new ronda 762 movement. There are different versions of this ronda 762 movement with different cannon pinion height. The movement that I used was one with a 4.25 mm cannon pinion known as ronda 762 H3. I bought also a longer winding stem. Of course you need a new plastic spacer around the movement. I cut that out of a 4mm thick pvc sheet (for pvc windows) and I made new dial feet by soldering copper wires of the right diameter to a thin cooper foil. The cooper foil can then be glued to the back of the old dial. Below is a picture where the new dial feet are already inserted into the movement. I have protected the movement with an acetate sheet (a thin plastic sheet) in case any excess glue ends up besides the cooper foil. To install the dial I put lepage 100% repair glue on the cooper foil and then I just place the dial on top. I make sure it is aligned and centered. The glue needs to dry for a week to get maximum strength. The second picture shows the "new Timex pocket watch" with the ronda 762 inside. A challenge was also to make the old watch hands fit.

ronda 762 movement: installation of new dial feet

The Timex pocket watch with a ronda 762 movement

References

Datasheet_762_Complete_technical_documentation.pdf, technical documentation for the Ronda Harley 762 movement

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