An 80-Hour Power Reserve is No Better Than 60

"We all take off our watches at night and put them on in the morning"

Patently untrue.

I hardly ever take watches off at night …

I wear a watch 24/7 and keep my automatics on winders when not on my wrist so they're available with minimal fuss when I want to wear them.

If I'm away with no winder then the longer the power reserve and I'm swapping watches, the better. If your use case doesn't match mine then it doesn't automatically make yours the correct one.

Thank you for thinking of this. My brain is so lazy I don’t even think about these type of things..until I read a post on watch crunch. Lol so interesting! And I agree with you! except taking my watch off every night. Sometimes I fall asleep with them on 😂 again…lazy…😂

For me the power reserve doesn’t mean much to me. 40 hours to 8 days, Panerai even has a 10 day power reserve it all the same. Doesn’t change my opinion about the watch. I wear my watch for a few days take it off and put on another one. By that time the power reserve is over on the watch I’m putting on. So I set the time, spin the crown and off to the races. No big deal for me.

Actual mileage may vary.

I never take off my watch at night, if the one I use during the day doesn’t have lume, I change it for a diver! It all depends on how many watches you have on rotation. In my case, most of the time when I change my watch the new one is dead and I have to wind it and set it up, is part of the routine. Some of my watches have 70 hours reserve and it’s the same.

I'd be happy with 24 hours tbh, I never am without a watch on wrist & tbh long power reserves are useless to me. I'd swap power reserve for a higher beat or increased accuracy in a heartbeat 😉👌🏻

Assuming for a moment anyone in the universe uses watches as intended — I don’t usually take them off at night or whathaveyou, but that’s a whole tangent of I’m wearing a watch I can’t see in the dark — then you will have a dress watch for evening events, and a daily watch for work, with likely a third for weekend pursuits. It’s possible the weekend pursuits may also be your ‘at home evening’ watch.

None of which matches the ‘x days off’ model proposed here, but that’s ok — the power reserve is a convenience thing, and in an era where people may barely move their wrist in the day, is largely compensating for more sedentary lifestyles. But! The idea of a five day power reserve is a nice ideal, because it is logical that a person may take their weekender (say, a diver) off on Monday morning before work, and not wear it again (unless it’s the ‘at home evenings’) until the Friday evening.

A dress watch ideally has no complications of course, so it’s matter of a few seconds to put it right if your posh events are more than a few days apart — but of course, in the luxury world of watches, that’s only every other night anyway.

Coming back to the real world, I probably should take some of my watches off at night if I am wearing them— the manuals suggest it, and it gains time off wrist dial up, and loses it on wrist. Only two seconds mind you.

Atm, I have to stop wearing my dressy Solar come sundown, because I can’t see the hands in the dark. No lume, though they are much more elegant as a result.

Interesting to see how use cases vary in terms of how people use individual watches, how they manage collections, and how they feel about winding/setting or keeping watches wound/set.

I have 36 watches. About 20 are mechanical. I rotate wearing them daily on a mostly random basis. I take my watch off at night. I don’t mind winding/setting a watch in the morning. I don’t have watches with complications beyond the date (two GMTs, and I don’t use the GMT function).

So I only really need an 18 hour power reserve. Anything more is cool, but really just gravy for me.

Before I leave the house I put watches on my pets and they wind them for me

That isn't entirely accurate. After 36h (a day and a night) watch with a 48h power reserve will have lost a lot of the energy inside the mainspring and about 75% (edit: this isn't exactly accurate but let's just roll with that number, it is too complicated otherwise 😬) of its torque according to Hooke's law for torsion springs. A watch with 80h of power reserve will have lost less than 50% of the torque. In theory (and to some extent in practice) this results in better timekeeping. So all things being equal a higher power reserve is better as the amplitude won't drop as much over night.

However, all things are never equal and so one must ask at what cost does a higher PR come. usually that is down to less inertia in the balance wheel and/or a lower beat rate paired with a possibly thinner mainspring. That in theory (and to some extent in practice) means worse timekeeping at full wind.

As such power reserve is a trade off. If you wear your watch all the time you want good timekeeping at full mainspring capacity and as such a high beat rate. In that case power reserve can be low so that it comfortable gets through the night but a weekend. If on the other hand you leave your watches regularly for a whole day and don't want to set them again, 48 is enough to keep them running but over a longer period of time you will likely see better timekeeping with a higher PR.

I had an Oris with the cal. 400, and I wished I had the sellita ones instead, the 5 day power reserve never mattered and in fact the big twin barrels lost significant torque as they wound down making the watch lose time as the power reserve dwindled. I think the new manual wind one fixes this by giving you a power reserve indicator so you always keep it topped but at that point I rather have a simpler movement, I think 70 hours is the sweet spot.

Power reserve is a good thing and more of a good thing is always good.

Until you meet someone who likes cats. 🤣🤣🤣

op clearly is NOT a watch person. A REAL watch person wears several watches each day = infinity PR :rolleyes:

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QUARTZ!

I don’t see the point between a 60 hour and a 80 hour power reserve but absolutely value the 120 hours of power reserve like on the GS 9RA5 movements cause it means I can put the watch down Monday night and pick it up again on Friday with it running perfectly. Really useful when you have multiple watches in your collection.

I did that, with manual version of your same movement. There is a difference. Over about a month of measurements, after a “full wound I’d” have approx between 2 and 4 seconds of delay per day. After no wound between 0 and 2. I didn’t run the statistical tests but as a trend it’s clear. And surprising: as the main spring loses energy, my watch becomes slightly more precise. Unless I am doing a bad job at eyeballing the data, I am on mobile and can’t really do anything more sophisticated than that.

however that’s just my watch. Could be reversed if for example mine was gaining seconds rather then losing them (just shift the distribution above 2 seconds to the right and I have exactly the opposite effect). However the point is that there is an effect, which supports the argument that PR does matter even if the additional hours do not end up being “on the wrist”.

Data below. All winding and measurement happened in the evening, approx 24 hours since the last update. Below “winded” (sic.) yes indicates that after that measurement, the watch was fully wounded. So effects should be evaluated shifted by one day (ie wounding today has an effect on tomorrow’s reading).

You could get the Panerai with the 8-day movement, ie 192 hours of power reserve. I found that to be quite convenient.

Thanks for sharing. There is an obvious and reproducible change between day 1 and day 3. (I was only going to do it once!) However, it is just a couple of seconds. It’s not so extreme that I’d set my watch. Nor would it sell me on an 80-hour PR over a 60-hour PR. ¯\_(ツ)_/¯

The physics ignores a lot of things but amplitude does drop as the mainspring winds down and that definitely affects the rate of a watch. Very expensive watches use constant force devices to prevent that.

I did that experiment with 4 Rolex 3135 movements, they run with about twice as much error, maybe a bit more, on day two than on day one. Pretty much all of them. Eg a watch that runs at +2 spd would have gained about 7 seconds after two days sitting. Shortly after that they die as they have about 50h of power reserve in my experience. So the difference wasn't all that big but it was noticeably worse. I don't have a 3235 but that would be a great comparison as it has 70hr of power reserve (probably a bit more in practice).

Did you see this comment? Another commenter did the experiment with a Powermatic 80 and screen capped the results. https://www.watchcrunch.com/hatchr/posts/an-80-hour-power-reserve-is-no-better-than-60-41458#comment-563289

Power reserve doesn’t really mean anything to me. I choose my watch depending on mood on a daily basis and I have enough (as I imagine most of the people here do) so that I may or may not wear a particular watch til the following week. Then the power reserve means piss all. On days that I do end up repeating a watch within the week, I don’t actually mind if I set it up again. It’s become a calming morning ritual, right before showering. Any opportunity to play with a watch has become an affirmation exercise to remind me why I love this hobby.

Oh and I don’t wear my watches in bed. I like to sleep nekkid so it’ll just be weird to wear a watch and nothing else.

With 8 watches, I seldom wear the same one two days in a row anyway, so it literally never matters.

Wound right up will probably get it to the max but you would run the risk of causing the mainspring to slip as it is supposed to do for overwinding. Just because it has a limit does not mean you should take it there. The only way you would do it is hand winding because the auto would not be strong enough.

I didn't see that, excellent, thanks. By that it would seem that it does make a difference in the rate also for a powermatic. In theory one would likely regulate the movement to run perfectly at full wind, especially automatics as those keep themselves wound, and so any deviation from that is (again in theory) undesirable.

In practice it can of course average itself out by negating any error due to imperfect regulation at full wind, which is ideal but not a rule.

Buy a credor then lol

My question on all of this is, without a power reserve indicator, how does one know when the mainspring is fully wound?

I have a desk job and spend a lot of my day not actually moving, so by the time I get home from work, has my watch actually been wound up enough to hit the maximum power reserve figure quoted? Often, no.

Im with you on that..I try to keep a active rotation of five watches but it never fails I decide on a whim to just grab one and of course i have to wind and set it but heck that is part of the hobby..JMO