Reference Guide · Updated September 20, 2026 · Guía de Relojes Team

Sundials: no batteries, no maintenance

How Citizen’s Eco-Drive, Seiko’s Solar and Kinetic work, how much power reserve they have and how long the cell lasts.

Quartz, automatic or manual: which to choose and why

The quartz It is the most accurate and the most practical: it diverts around ±15 seconds per month, it needs nothing more than a new battery every 2–4 years and is more shock-resistant. The automatic It is powered by a wrist movement and deflects between -10 and +30 seconds a day (a COSC-certified calibre has a rate of between -4 and +6), but it is the one with a mechanical soul, a sliding seconds hand and long-term value. The manual It needs to be wound every day and is usually more delicate, which is why it’s used in dress watches. If you’re looking for accuracy, go for quartz; if you’re looking for fine watchmaking, go for an automatic.

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Solar and Eco-Drive: the maintenance-free option

If you don’t want to change the batteries or set the time, solar technology is the most practical solution on the market. The Eco-Drive Citizen charges a cell using any light, including artificial light, and stores energy to 6 months in total darkness; the Seiko equivalent is the Solar, and its Kinetic generates electricity from movement. The Spring Drive The Grand Seiko is a hybrid watch with a perfectly smooth seconds hand and quartz-level accuracy. The solar cell lasts between 10 and 20 years – far longer than the batteries it replaces – and the capacitor is replaceable.

Accuracy: how to tell if your automatic gearbox is working properly

An automatic watch is not a precision timepiece, and you shouldn’t judge it as such. To measure it properly, set it to the same time for seven days in a row treat it as normal and calculate the average daily deviation: within -10 / +30 seconds a day This is within the factory specification for an uncertified calibre. If it falls outside this range, it is almost always corrected by means of a regulation at a watchmaker’s (€30–60), not as part of a repair. A useful tip: the position in which you leave it overnight affects the result, so if it’s running fast, you can leave it face up, and if it’s running slow, with the crown facing upwards.

The gauges that are actually inside

Almost all automatic cars costing less than €500 are fitted with one of these engines: Seiko NH35/4R35 (reliable, hackable, 41-hour power reserve, the standard for affordable watches), Miyota 8215 (cheap, second hand with a slight wobble) or Miyota 9015 (finer and at 28,800 alternations). Moving up, we find the ETA 2824-2 and its equivalent Sellita SW200, and the Powermatic 80 by Tissot, which stands out for its 80-hour power reserve. Knowing the calibre tells you more about the watch than the brand: two watches with very different price tags may share the same movement.

Power reserve – and what happens if you don’t have one

Power reserve is the length of time an automatic watch continues to run after you stop moving it: typically, this is 38–41 hours in traditional calibres, which means that if you take it off on Friday night, it will have stopped by Monday. Modern movements have extended that figure: the Powermatic 80 lasts up to 80 hours and some current calibres at 70. For several automatic watches, a rotary box It keeps them running, although this isn’t essential: leaving it switched off won’t damage the mechanism; it just means you’ll have to set the time again. What is advisable, however, is a service every 5–8 years.

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Bezel: why the diving bezel only rotates in one direction

The rotating bezel on a diving watch is unidirectional For safety reasons: it can only move anti-clockwise, so that if you bump into it by accident, it can only shorten the calculated dive time, never extend it. That of a GMT is bidirectional and features 24 markings for reading a second time zone. The tachometer A chronograph allows you to calculate your average speed over a kilometre. And on a dress watch, a slim, polished bezel is what makes the case appear smaller and more elegant than it actually is.

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Frequently asked questions about Citizen Eco-Drive

What width of strap do I need?

Check the distance between the lugs: 18, 20 and 22 mm will fit most watches. If your watch allows it, look for quick-release pins so you can change the strap without tools.

Can I have a shower whilst wearing a 5 ATM watch?

It’s not advisable. Five atmospheres is measured under static conditions, and the shower jet generates higher pressure peaks; what’s more, the heat causes the seals to expand. For worry-free use with water, you need 10 ATM, and 20 ATM if you’re going diving.

Will an automatic car break down if I leave it standing?

No. Leaving it switched off won’t damage the mechanism; you’ll just need to set the time when you use it again. What it does need over the years is a service, every 5–8 years depending on use.

Is a quartz watch or an automatic watch better?

For accuracy and peace of mind, choose a quartz watch: ±15 seconds a month and a battery change every 2–4 years. For long-term value, choose a mechanical watch with a sliding seconds hand and automatic winding, with a tolerance of between –10 and +30 seconds a day and a service every 5–8 years.

How much do I need to budget for a Citizen Eco-Drive?

It depends on how you plan to use it: there are good options in the entry-level range, as well as advanced models that are only worth the extra cost if you’re going to make the most of their features. Check the criteria in this guide, work out how you’ll actually use it, and compare the current price on Amazon before making a decision.

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