How Does a Luxury Watch Power Reserve Work?

Posted by Chris on Thursday, September 22, 2022
luxury watch power reserve

If you're any sort of connoisseur of luxury watches, then you're certain to have come across some automatic watches that have power reserves. But what exactly does that mean? Do these watches have batteries?

It's actually a lot more complicated than that, as any worthwhile thing is in the world of luxury.

Today, we will demystify the mystery of the luxury watch power reserve. But first, let's take a quick look at how automatic movements work.

How a Watch's Automatic Movement Works

The defining feature of an automatic movement, as opposed to a quartz or manual one, is that it has a rotor. This is a metal weight that's attached to the watch movement and swings freely when your wrist moves.

As the rotor swings, it turns a winding mechanism which is connected to the mainspring. The mainspring is what stores energy in the watch, and releases it gradually to power the movement.

The rotor is connected to the mainspring through a series of gears, and this is where things can start to get a little more complicated. The rotor can wind the mainspring in one direction only, so the gears have to ensure that the mainspring is always wound in the correct direction.

This is why automatic movements will sometimes have a "winding bridge" visible on the back of the watch. This is a gear system that's designed to change the winding direction of the rotor, so that the mainspring is always wound correctly.

Wait, What Exactly Is a Mainspring?

The mainspring is a long, tightly-coiled strip of metal inside the watch movement. It's connected to the winding rotor at one end, and the other end is attached to a gear called the "barrel."

As the rotor turns, it winds the mainspring around the barrel. This stores energy in the mainspring, which is gradually released as it unwinds. The energy from the mainspring powers the watch movement, making all the hands move to tell the time.

The mainspring in an automatic watch is usually much bigger than in a manual or quartz watch. That's because it has to store enough energy to keep the watch running for a long time, even when it's not being worn.

Which brings us to the concept of power reserve.

What Is Power Reserve?

The power reserve of a watch is simply how long it can run before it needs to be wound again. The mainspring in an automatic watch is designed to store enough energy to keep the watch running for a specific amount of time.

For example, a power reserve of 48 hours means that the watch will keep running for two full days without being worn. After that, it will need to be wound again in order to keep working.

Some watches have much longer power reserves, of up to seven days or even more. Of course, the longer the power reserve, the bigger and heavier the mainspring will be.

How Is Power Reserve Measured?

The power reserve is measured in hours, and it's usually listed prominently on the dial or case back of the watch. It's important to note that the power reserve is not a measure of how long the watch will actually run for.

The power reserve is simply how long the watch will run if it's not worn and the mainspring is fully wound. In reality, most people wear their automatic watches every day, so the mainspring is never fully wound.

As a result, the actual running time of an automatic watch can be much shorter than the power reserve. For example, a watch with a 48-hour power reserve will usually only run for about 36 hours in real life.

This is because the mainspring gradually winds down as the watch is worn throughout the day. By the end of the day, the mainspring is usually only partially wound, and it needs to be fully wound again in order to run for 48 hours.

Why Is Power Reserve Important?

The power reserve is important because it's a measure of how long the watch will keep running without being worn. If you don't wear your watch for a few days, you can be sure that it will still be keeping time when you put it back on.

Of course, the power reserve is only relevant to automatic watches. Manual and quartz watches don't have a mainspring, so they don't have a power reserve.

WatchMaxx Has Luxury Watches With Power Reserves

If all this technical talk of automatic movements and power reserves has gotten you thinking about picking up a new luxury watch, then you're in the right place. We have all kinds of luxury watches with automatic movements, across all price ranges, in stock and ready to ship.

Many find that a brand new watch is exactly what they needed to get wound up for their own power reserves, and we couldn't agree more.

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