Sellita · Sellita SW510 chronograph

Oris Aquis Chronograph, TAG Heuer Formula 1 and Raymond Weil Millesime power reserve: inside the Sellita SW510

The Oris Aquis Chronograph, TAG Heuer's Formula 1 automatic chronographs, the Raymond Weil Millesime Chronograph and the Bell & Ross BR-05 Chrono all run on versions of the Sellita SW510. Current versions last about 62 hours from full, roughly two and a half days, though some brands quote less.

Updated September 2026 · Based on manufacturer specs, published reviews and watchmaker/owner reports

Watches that use the Sellita SW510

The SW510 is Sellita's version of the Valjoux 7753 layout: a cam-operated automatic chronograph with the counters at 3, 6 and 9 o'clock. It's the go-to automatic chronograph for brands that can't or won't buy from Swatch Group, and most brands give it their own name. Oris calls it the 771, TAG Heuer the Calibre 16, Raymond Weil the RW5030 and Bell & Ross the BR-CAL.326. The quoted reserve varies with the version and the year, so it's shown for each.

Specs at a glance

History and where it came from

Sellita launched the SW500, its version of the Valjoux 7750, in 2009. It arrived as Swatch Group was cutting outside brands' access to ETA, and it gave them an automatic chronograph they could still buy. The SW500 keeps the 7750's familiar 6-9-12 layout. In 2017 Sellita added the SW510 series, which moves the counters to 3, 6 and 9 like the Valjoux 7753, and a year later came hand-wound "M" versions, monopushers and more. The family now runs to dozens of variants.

The important recent change is the reserve. Older SW500-family movements were in the 42- to 48-hour range, like the 7750. Current automatic SW510s are specified at 62 hours, and brands have been updating their watches to match. Oris's 2024 Aquis Chronograph is the clearest example: Monochrome notes that it went from 48 hours with the old calibre 774 to 62 with the SW510-based 771. Not every brand has moved, and TAG Heuer still quotes 42 hours for the Calibre 16 in the Formula 1.

Accuracy in the real world

Accuracy depends on grade and on how much the brand regulates it. Oris, TAG Heuer, Raymond Weil and Bell & Ross don't publish daily-rate figures for these watches, and there aren't many published timegrapher results. Owners generally describe them as running like any decent 4 Hz Swiss movement, within several seconds a day when regulated.

Two chronograph-specific points apply. Running the chronograph takes energy from the mainspring, so amplitude and rate can shift slightly while it's running. And on a cam-operated chronograph, the central seconds hand may jump a little when you start it. Both are normal for this design, not faults.

Reliability and servicing

The 7750 architecture is one of the most serviced chronographs in the world, and the SW510 benefits from that. Any watchmaker who knows a 7750 can service it, and parts come from Sellita's open supply. A chronograph service costs more than a three-hander because there are more parts to strip, clean and adjust. Most brands suggest a service interval of around five years.

Branded versions are usually serviced by the brand, especially where the rotor, date or finishing is custom. Oris's calibre 771 comes with Oris's own warranty and service network; TAG Heuer and Bell & Ross prefer watches to go back to them.

Quirks worth knowing

• It's thick. The 7750 family isn't slim, and neither are the watches: the Oris Aquis Chronograph is 16.2 mm tall and the TAG Heuer Formula 1 Chronograph 14.1 mm.
• One-way rotor. Like the 7750, the SW500 family winds in one direction only. Some owners notice the rotor spinning freely the other way, which is normal.
• Pushers and water. Don't press the chronograph pushers underwater unless the brand says it's safe, even on a diver like the Aquis Chronograph.
• Date danger zone. Avoid the quickset date late in the evening. Here's why.

How it compares

• Valjoux 7750: the original, with a longer track record and about 42 hours. Mechanically very close; the SW510 now wins on reserve.
• ETA A05.H31: Swatch Group's modernised 7753 with 60 hours, found in the Tissot PRX Automatic Chronograph and Heritage 1973.
• TAG Heuer Calibre Heuer 02: TAG Heuer's in-house column-wheel chronograph with 80 hours; the step up from the Calibre 16.
• Sellita SW200-1: the simple three-hand Sellita; 38 hours.

Living with the 62-hour reserve

A current SW510 gets you across most of a weekend. Take your Oris Aquis Chronograph off at 6pm on Friday and, from a full wind, it's still running at 8am on Monday, so if you pick it up first thing, you won't have to reset it. A TAG Heuer Formula 1 Chronograph rated at 42 hours is a different story: take it off at the same time and it stops around lunchtime on Saturday.

Chronographs are heavy on energy. A lot of timing, or a spring that wasn't full when you took the watch off, will cut into that figure. Watch Winder counts down the reserve for each watch you own and reminds you before it stops. Enter the figure your brand quotes. To check a particular weekend, try the "Will my watch stop?" calculator.

Verdict

The SW510 is a robust, serviceable automatic chronograph that has quietly outgrown the 7750 it copies, at least on reserve. It's the reason the Oris Aquis Chronograph and Raymond Weil Millesime can offer a 62-hour chronograph at their prices. It's thick, it winds one way, and the reserve depends on the brand and the year, so check the spec for your watch. For a brand-built chronograph with a long track record, it's hard to fault.

FAQ

How long does the Oris Aquis Chronograph run off the wrist?

Oris quotes 62 hours for the calibre 771 in the 2024 Aquis Chronograph, about two and a half days from a full wind. The earlier model with the calibre 774 was rated at 48 hours.

What is the power reserve of the TAG Heuer Formula 1 Chronograph?

The mechanical Formula 1 Chronograph uses the Calibre 16, based on the Sellita SW510, and TAG Heuer quotes 42 hours.

What movement is in the Raymond Weil Millesime Chronograph?

The calibre RW5030, based on the Sellita SW510, with 27 jewels and a 62-hour power reserve.

Does the Bell & Ross BR-05 Chrono hack?

Yes. Its BR-CAL.326, based on the Sellita SW510, stops the seconds when you pull the crown to set the time. Bell & Ross quotes 60 hours of reserve.

Is the Sellita SW510 a copy of the Valjoux 7750?

It follows the Valjoux 7750/7753 architecture, with Sellita's own changes such as eccentric-screw regulation and, in current versions, a 62-hour reserve.

Does running the chronograph drain the power reserve?

Yes, a little. The chronograph takes energy from the same mainspring, so a watch that's been timing things for hours will stop sooner than the rated figure.

Sources

• Monochrome: Hands-on with the revamped Oris Aquis Chronograph
• Monochrome: The all-new TAG Heuer Formula 1 mechanical chronographs
• Monochrome: Raymond Weil Millesime Chronograph
• Monochrome: Bell & Ross BR-05 Chrono S.T. Dupont
• Grail Watch Reference: Sellita SW500 family

Keeping it running

• On an average day an automatic gains roughly 4 hours of reserve per hour on the wrist, so about 16 hours of wear fills the Sellita SW510 chronograph. Desk days charge more slowly.
• Most automatics can also be wound by the crown. If yours has stopped, a few dozen turns gets it going before you put it on.
• Off the wrist it stops about 62 hours after it was last full. Stopped sooner?
• On a watch winder, start at about 800 turns per day, clockwise. Winder settings for every movement.
• If it does stop, don't set the date between 9pm and 3am. Check if it's safe.

All Sellita movements

Never let it stop

Watch Winder counts down the reserve of every watch you own and reminds you before one stops. It already knows the Sellita SW510 chronograph: type your watch's name and the reserve fills itself in.

Manufacturer's published figure. Real reserve varies with the watch's age and service; check your manual.