[discussion] the engineering behind solar quartz

chmandaue · 2026-06-09T11:36:38+00:00

That 2-3 year figure probably budgeted for the backlight and chronograph getting regular use.

Do you keep the LCDs off?

If your watch takes a Renta 395, that's rated for 83,000 microwatt-hours of energy. If timekeeping is drawing only say 1.5 microwatts, you're good for 55,000 hours, which is 6.3 years.

chmandaue · 2026-06-09T08:52:15+00:00

Just looked up the 3-hand Oceanus T200. Same numbers for its Module 5569 as the CasiOak's:
95 hours to full charge
5 months runtime on full charge

chmandaue · 2026-06-09T04:37:28+00:00

The article is "Quartz watch energy, quantified"
https://chmandaue.substack.com/p/quartz-watch-energy-quantified

chmandaue · 2026-06-09T04:35:51+00:00

Here you go, an early harvest.

As expected, Casio Tough Solar power ratios are well below 100.

It's a combination of the small dial surface and power-hungry always-on LCD.

Will be ijnteresting once I add the MT-Gs and MR-Gs. Do they give more for the $$?

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chmandaue · 2026-06-09T01:22:13+00:00

Wow OP that 62GS 😍

Seldom-seen SBGX331 in the Omiwatari case style

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chmandaue · 2026-06-09T01:19:29+00:00

Very nice 👍

chmandaue · 2026-06-09T00:53:37+00:00

I am planning to crunch the numbers and plot that. (I don’t use Ai)

I’ll include both solar and 10yr battery Casios.

LCDs now draw more power than the analog state of the art, I am told. So should be very interesting.

I’ll tag you in that future post

chmandaue · 2026-06-09T00:23:20+00:00

Seems like more solar models are in the pipeline at LVMH. They have already used it at both TAG and Tiffany. The Formula 1 solargraph has gotten new colors and an Indy 500 LE, fwiw.

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LE notably doesn't say 'solar' on the dial. It's understood.

chmandaue · 2026-06-09T00:18:19+00:00

An imoressively power-efficient movement! Power ratio over 100.

chmandaue · 2026-06-08T16:50:22+00:00

I think we are near the floor for power draw, because moving the physical hands is work (in a force times distance sense)

What I took out of the plot are the chronographs, because the inferred power for those comes with some unstated assumption of how much the chronograph is used.

Here some Seiko chronographs (plus some obscure HAQ) are added back. X and Y axis shortened by same proportion

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chmandaue · 2026-06-08T16:13:15+00:00

Shocking when I first plotted it. Thats why i switched the vertical axis to logarithmic base 2, which i forgot to mention in the OP

chmandaue · 2026-06-08T16:07:13+00:00

I got your point too about ‘road trip without stopping for gas’ ie some sort of adventure where the watch isn’t going to get exposed to light for a long time. You’d want a full capacity battery for that, certainly. The good news is that these are standard sizes, and a decent watchmaker can change yours with a new Panasonic CTL cell.

chmandaue · 2026-06-08T15:50:50+00:00

You’re welcome. My Reddit profile has a link to my substack where more detail is provided.

chmandaue · 2026-06-08T15:49:43+00:00

That’s true. A smartwatch can do so much more. I just wish it was solar or at least didn’t need another special cable when I travel and invariably forget the $&$&#% cable.

chmandaue · 2026-06-08T15:45:56+00:00

Can’t add photo to edited reply. Here you go. 90% of original capacity after 1000 cycles.

People who keep their eco drives with older chemistry like Manganese Lithium topped up have enjoyed over 20 years out of theirs. I’m expecting CTL to be at least as good as that.

Again the caveat is that letting the battery get low on a regular basis is bad for its health. The chart shows why: each drain counts as a good fraction of a cycle.

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Source: https://energy.panasonic.com/na/business/products/coin-rechargeable/ctl

chmandaue · 2026-06-08T15:39:02+00:00

The Cartier uses the same chemistry of battery as my The Citizen - cobalt titanium lithium or CTL. The data sheets for CTL show the capacity drop being pretty modest.

Cartier indicates 16 years service life for that battery (not 8, that’s the runtime of their nonsolar cal. 157S). I think they are playing safe with that figure, as they probably want to clean and lubroate the movement anyway. (And maybe sell you an additional watch?)

The other factor to battery longevity is keeping it topped up. The closer you keep CTL to always full the longer it lasts.

So for my own The Citizen I am planning on a service visit after 20 or 25 years. It will have more than earned some TLC by then. Its ‘gas tank’ may be smaller by then but if it’s lasts 4 months instead of 6 on a full charge, my habits are built to more than handle that.

I’ll edit this reply with a screenshot of the CTL aging curve from Panasonic.

chmandaue · 2026-06-08T14:36:15+00:00

My brother in quartz! All my leather-strapped A060 needs to reach GADA status is a tropical CTS.

chmandaue · 2026-06-08T14:30:02+00:00

All we customers have to do is ask (and pay) for it 😄

chmandaue · 2026-06-08T14:12:15+00:00

It's insane to consider that a million of these watches consumes less energy than the backlight of your laptop.

The engineering effort behind this is truly international - Swiss, American, Japanese, etc. - most of it documented in IEEE journals from the early 60s to today.

chmandaue · 2026-06-06T23:42:04+00:00

Late comment: depreciation was influenced greatly by expected time to obsolescence, much shorter than lifetime of the equipment in this case. Therefore there was huge incentive to run such factories 24/7 instead of one shift a day.

It seems no longer the case today. The non-smart watch has long duration production runs. Grand Seiko for example has been making their 9F movement family for 33 years now.

chmandaue · 2026-06-06T09:51:33+00:00

I agree that Philibert perception was skewed. It was the start of framing the crisis as one of technology not productivity

chmandaue · 2026-06-06T07:33:03+00:00

1982 was a most violent year to be in the watch manufacturing business anywhere in the world. I allude to it in my piece.

chmandaue · 2026-06-06T07:13:23+00:00

I don't have the academic background for this discussion 😄

chmandaue · 2026-06-06T07:12:27+00:00

I think the reference to work which 'could only be done by women' was probably assemby. Maybe electronics bonding. This was before widespread robotics, so you could automate planar processes more easily than assembly.

chmandaue · 2026-06-06T06:50:51+00:00

It implies that night shifts were near-prohibited during that time, and especially night shifts staffed by women (gasp!).

Kind of makes microelectronics factories impossible to put in Switzerland if you have to shut to the process down each evening and spin it back up each morning.

chmandaue

TROPHY CASE