Both bathroom and kitchens scales are large enough they can run on AA / AAA batteries and casually go a decade (or more) without replacement.

Tangentially: I used to have a 3 button timer, it was a little LCD countdown display and 3 buttons. One button set hours, one minutes, and one starts / stops the countdown timer. I found this timer when I was a kid, used, and the 1 AAA battery it had lasted into adulthood, literally decades. I have since bought almost the exact same device - 3 buttons, one display - a few different times and the newer ones only last a year on the same battery.

What's going on here? Presumably someone designed a new 3 button timer, since they can't just steal an existing schematic, and I guess just nobody cares to make it good? Why don't all 3 button timers last multiple decades on a AAA battery?

I've seen the same thing with other small electronics, like the dozen or so stopwatches I've owned in my life. A few of them go strong for decades, others have their LCD display start fading in a year.

> Both bathroom and kitchens scales are large enough they can run on AA / AAA batteries and casually go a decade (or more) without replacement.

For bathroom scales, sometimes the design doesn't permit batteries larger than button cells, since the entire scale is a piece of tempered glass with four 1/4" tall feet and a lighted LCD display that shines through the glass. I like this particular design because it's thin enough to fit under a door as it swings. Batteries in my scale last over a year with near-daily use, and mine has a very bright display.

My relatives have a similar type of bathroom scale.

When the button cell ran out, I popped in another one we had lying around.

One month later, the button cell was dead, after using the scale a handful of times. Obviously something was draining the button cell battery when the scale wasn't in use.

I could try and debug the scale, but given that even ten minutes of investigation would be more than the amount of time I spent using the scale in one year, I just decided to remove the button cell when the scale wasn't being used.

Two years later, that button cell still works in the scale...

I buy a lot of those little timers for my business. They get pretty heavy use, maybe running timers for about 6 hours per day. They don't last anywhere near decades for us.

Anyway, my insight is simply that some of them turn off the LCD after a while of non-use, and some of them keep it on indefinitely. Maybe that explains the difference between your two experiences.

The timer I had never turned off the LCD. I found it in early elementary school and the same battery was still going strong when I got married in my late 20s. So it lasted 15+ years on a single AAA battery.

I had the same exp. One I bought in the mid 90s. That original battery that came with it lasted nearly 10 years. Then another 5 with the new battery. I retired it when the plastic casing came apart. The LCD never turned off. That thing was a tank.

The newer ones I am lucky to get a year out of the battery. Even using the on/off switch.

I've noticed something similar with remote controls. Receivers, CD players, DVD players, Blu-ray players, TVs, cable boxes...almost every one I've ever bought came with batteries that lasted for many years. Sometimes longer than the device the remote controlled.

Then, when the remote needs new batteries and I put in the batteries sold in US stores they would last a year or two.

The batteries that came with these devices were brands I'd never heard of and never seen at any store in the US. Usually they had lots of Japanese-looking writing on them and little English except for the brand name.

I've noticed this too. A couple things:

1) The OEM battery was probably fresher than the one that wound its way through retail distribution and then sat in a drawer at your house for longer than you realize

2) By the time you have to replace a battery, your remote's PCB has had time to adsorb water and contaminants from the air, get soda spilled on it, etc and is going to have higher leakage. It will then always draw more current in standby.

Batteries are sold with an expiration date on the package, and I don't think that's usually decades out.

In the 80s I remember seeing expiry dates on AA packs of 99, and my child-brain thought they didn't expire so they put a meaningless number there instead - I couldn't process the idea of the year 1999.

I've had the opposite problem. I was reading a lithium battery package many times, frustrated that I could not find the expiration date. I finally realized that "2032" was printed as a year and was not an alternate size code.

CR2032 is a battery size, sometimes the CR is dropped due to the small size of the package.

https://en.wikipedia.org/wiki/List_of_battery_sizes#Lithium_...

But 10 years is also the rated lifetime for CR2032 cells. Those made in 2022 will definetly still be good to use in 2032. I've had some last as PC CMOS ram backup cells since the late 90's and they are not rechargeable, nor being charged in the system they are in.

I know, hence my brain ignoring the marking for the longest time. This was a package of AA sized batteries, not coin cells!

Sounds like nearly decades to me if buying in 80's and have an expiration of 99... Just because a childlike brain of hours can't understand that sort of time doesn't mean it's not literally decades.

That's asking for corrosion damage from the battery.

I've got a bathroom scale that goes several years on it's pair of coins even though it turns on only when stepped on. I suspect there's a physical switch involved, though.

why don't they use gravity as the power source? I've seen scales that require pushing a button several times to power it. Getting rid of the button and using the full scales' surface seems like the next step.

i have read that the build quality of batteries has dropped.

IIRC it's not really the build quality, it's the new limitations around chemical composition inside the battery. I'm not sure about non rechargeable lithium batteries, but I think alkaline leak more and last less due to mercury getting phased out. Some newer Li-ion cells might also suffer from having less and less cobalt inside, due to high cost and supply related issues. Both are good trade offs, especially since alkalines are probably on the way out and manufacturers are getting better at making lithium batteries without cobalt

I have a digital LCD clock, a giveaway by NTT from a trade fair, that still works with the same single Maxell AA battery since 1998. The battery quality must have been amazing at the time, or the clock uses almost no power. I honestly don't know how that's possible. :D

I remember getting a digital watch in a box of cereal in ~1990 or so. That thing lasted 10+ years on just the battery inside it.

Ine the same way designers discussed above try and big dick their designs, clocks when through some EE big dicking on trying to minimize battery usage. Same thing with LCDs.

They got them to really low power usage. Some of the ones today would basically last your whole life on a single button cell.

I have this ultracheap made-in-China big kitchen clock, with a single AA that I've replaced twice in eight years. I don't buy expensive batteries, more like in line with the clock.

It has second hand (the kind that doesn't tick but appears to move uniformly) so there is some extra mechanical work.

I think the quality is hit and miss, even with premium batteries. I had enough devices damaged or entirely ruined by a leaked battery so now I remove them from anything not actively used.

If anyone knows a reliable model for AA/AAA cells that will absolutely not leak when left unused in a device for year+ I would love to hear it.

I’ve had much better experience with energizer not leaking while Duracell is terrible. Searching the net for other experiences, I found some prepper forums discussing this and apparently Duracell tries to extract so much capacity from the cell they sacrifice wall and end thickness causing them to leak.

I don’t think anyone can say they absolutely won’t leak, but search these types of forums/subreddits and you find other recommendations as well.

We switched to buying USB-rechargeable AA/AAA lithium ion batteries. The brand we buy is Pale Blue, but there are many other brands.

These batteries have a regular form factor, with an added micro USB (and USB C on some larger battery sizes) port for recharging. They work really well for us and charge quickly (and conveniently — everything has a USB socket nowadays).

The price may seem expensive, but after 10 or so charge cycles they should have paid for themselves. I expect these batteries will be good for many hundreds of charge cycles.

I wouldn't recommend this personally, having had bad experiences with poor charge circuitry in integrated chargers like these (in my case it was in a 18650 battery). Get a good charger (e.g. eneloop), and then you can get generic rechargeable batteries incredibly inexpensively for it, without risking poor charge management causing overheating or battery failure.

The same little charger circuit built into the batteries also converts the lithium battery chemistry voltage to 1.5v making them a drop in replacement for AA and AA batteries.

Or are you saying you can get 1.5V lithium rechargables that work with an external charger?

Why use those instead of 'normal' rechargeables? Invest in a battery charger once and each battery will be cheaper.

The only USB chargeable ones I use are 9-volt batteries, those are awkward and I dont want to replace my charger

"normal" ones are usual NiMH which put out 1.25v. Standard alkaline batteries put out 1.5v.

Some devices care about the difference.

The tiny electronics that allows the lithium battery chemistry to be charged via microUSB also converts the 3.?v output to 1.5v.

Get IKEA's LADDA rechargeable NiMH, they are a rebrand of Eneloops, the some of the highest quality NiMH batteries available, and are made in Japan; all tests on YouTube and elsewhere consistently put them at the top of the line.

They have very low self-dishcharge rate (and even come precharged in packaging) and with recharge cycles ranging from 500 (for the highest capacity 2450 mAh AA ones) to up to 1000 (for 750 mAh AA/1900 mAh AAA ones). Also, they do not leak.

Big Clive suggests using nimh batteries for expensive electronics since they won’t leak. Also they are much better than they used to be, and there are many slow self-discharge brands that you can actually buy pre charged.

My solution for this sort of thing is the rarely-used devices get lithium cells. More expensive but they're not prone to leaking once they're discharged.

Energizer lithium. It's what I put in nice things I use infrequently.

> Kitchen scales, bit more use, at least once a day but again 2 button cells a year

I had a kitchen scale that would eat through its battery pretty quickly (within a month) even when not being used. I figured it could be an interesting project to open it up and try to figure out where the stray power draw was happening, but the obviously correct solution was just to leave the battery cover off and pop it in and out for regular use.

Anyway my current kitchen scale was given to me as a present and has a mini-usb input to charge an internal battery. I personally found it to be a bit overkill, but at least I wouldn't need to get a new battery all the time. Then I realized that it can't be used when plugged in and charging. As in even if it is fully charged, it will not work when plugged in a charging. I can't believe that design idiocy. The engineers/managers/everyone involved in the production of this product should be ashamed.

I dropped my kitchen scale and it broke, so I had to go shopping for a new one. Which was kind of fine since that scale wasn’t great. But finding a good scale turns out to be pretty hard!

In the end I found some review that compares different scales and as a reference they used an entry-level lab scale. So I figured, hey, why don’t I just buy the benchmark scale? It costs about the same anyway.

So now I have an ugly German lab scale that actually has an off button and runs on a 9v battery. Here’s hoping I never have to buy another.

This is the secret for lots of these things; if you step slightly above “home use” you can often find industrial/commercial products that will work just fine - though do be aware of the limitations in some.

Or you could go with fully mechanical balance scales.

I know what you mean, but I prefer to picture them trying to fit a massive equal arm balance and stack of reference dumbbells in their bathroom.

I have Sony WH-1000X M3 noise cancelling fancy pancy wireless headphones and they can't charge and be used at the same time either! It is lunacy. Is there some cracy cheap charging chip that has this drawback? The headphones were very expansive still ...

I have the same headphones and that is not the only quirk thats driving me nuts. It doesn't remember the last noise canceling setting i used. I almost always use them at home so i don't need NC but every time I turn them on its in NC Mode and I have to press the button twice.

Maybe you have it set to autodetect the current setting. You can set presets for sitting/walking/in transit, and it dynamically switches between them.

Maybe that's a security feature, as you probably don't want the lithium battery to explode near your head.

The electronics industry is sleeping on the job, because they have not defined standard sizes for consumer grade lithium batteries (that means with an inbuilt protection circuit). All headphones, etc. should be using standard batteries.

I have just replaced a battery on my laptop, it completely failed after 2.5 years of use - they are a consumable, not a durable good. All headphones, gaming mice, etc. are headed straight for the landfill when their battery fails, it is impractical to replace that inbuilt lipo cell as it has custom size and shape, etc.

I buy devices with replaceable batteries whereever possible.

While I don't disagree the battery in them lasts forever. Charge them while you sleep.

They should have taken the apple approach and put the charging port on the bottom so you couldn't even lay it flat on its bottom with the charger plugged in.

>” How much extra cost does a hard on/off switch add to the bill of materials?”

BoM cost is not the whole story; a physical switch can greatly complicate an assembly, and may require hand-soldered wires. In addition to those cost-related factors, external switches are usually quite ugly, and getting them right can be very challenging, so it’s much easier to just omit them.

I think this is special pleading. At the volume we're discussing a surface mount flow solder on off device is not going to kill the BoM, and could be designed not to be ugly.

It's no different to any other bad design. It could be better.

All phones and computers can be completely powered down. They're hardly ugly switches.

Ermm, most phones and computers cannot be completely powered down. Either by nit-picking (CMOS clocks) or soft-switches (ACPI, soft button power-on), there's always some voltage in the system unless your PSU comes with an actual hard power switch (and even then, again, CMOS).

They consume a lot less power, but leave an 'off' phone in a drawer for a month starting at 100%, it will not be 100% when you 'turn it on'.

In low-power mode even those microcontrollers are using just nA (yes that's nano-Amps). Vs 100's of mA in operation. So the battery life goes from hours to what should be decades.

I'm thinking the battery goes dead because of leakage currents through the rest of the circuits, which were probably not designed to the nA standard.

A solid-state Off switch would also need a good silicon device to cut current consumption at the battery. Which also costs something.

I understand and agree, but the use-case is a bit skewed since that's not even true for a bare "naked" battery or cell.

They all self-discharge [1], some chemistries more than others of course but phone batteries certainly do.

[1]: https://en.wikipedia.org/wiki/Self-discharge

Self discharge is easily an order of magnitude slower than the power draw of these devices while seemingly off.

> I think this is special pleading.

This is an emotional, low-quality response to what is a measured comment actually providing nuance to the discussion.

The parent poster is very clearly not saying that leaving off the power switch leads to a better experience for the consumer - they're just giving legit reasons that a design/marketing team might use to justify doing so. Please don't try to cheapen the knowledge that they provided like this.

I took it as "I think the reasons given are not legitimate, and are poor excuses for 'maldesign'.".

Where 'maldesign' is my dad's favourite word for every seeming design flaw or 'unreasonable' limitation. (-:

> All phones and computers can be completely powered down. They're hardly ugly switches.

iPhones (and I assume most Androids as well) can't be completely powered off. Neither can Macbooks. In fact, I'd guess that most modern digital things with non-replaceable batteries can't be powered off.

There’s a specific Dell laptop reset procedure that requires you to open the case and disconnect the battery so you can then press and hold the power button to get it to discharge all residual power. It’s a pain.

I had to do this a couple of times with a Lenovo that sometimes locked up completely when it went to suspend - battery was highly inaccessible so it was a 30 minute tense process each time - firmware update eventually solved the problem. Not sure what the solution for this is - something like one of those paper clip reset holes?

The caliper and kitchen scale already have buttons.

(they would both be shitty without a zero/tare button)

My $20 "Pittsburgh" calipers from Harbor Freight (don't judge) are still on their original batteries, after 6 years. They have a power button, and a separate zero button.

They don't actually turn off though. It just turns the display off. They need to continuously sense position since digital calipers measure movement increments rather than absolute position. That's why if you take the battery out and put it back in it will prompt you to re-zero the calipers.

Amusing video explanation: https://www.youtube.com/watch?v=KnDype-j3hk

It's not uncommon for them to be designed to require zeroing at each power on.

Many of these “auto zero” which is why you have to do the scale dance - tap it with your foot to turn it on, wait for it to say zero, then step on.

Yeah, my explicit mention of kitchen scales and calipers was intentional, they both become much more useful if the user can choose to zero the readout at any time.

This is less true for a bathroom scale.

Went not just stand on it while it tares and ignore the negative when you step off?

All the digital bathroom scales that I've encountered refuse to display negative measurements.

Well my kitchen scale does. Though I don't know many people who weigh less than five pounds.

And on off switches can result in a call to support ($) or negative reviews when idiots can’t turn it on.

In contrast to users who look for one but don't find it, who don't call support?

Seriously? Is 2022 and we didn't solve the switch button? I'm sorry but I just don't believe you.

It's weird but true. Adding physical switches to a device can be one of the most complex design elements. It complicates both the layout of the PCB and the design of the case. Finding a suitable switch is also a real pain, as parametric searches for switches don't work particularly well.

We did, but maybe not cheaply enough. If they can save a few cents by passing on the cost to you (in the form of more battery usage) they will do so as long as the market (or regulatory environment) doesn't mind.

Regarding Kitchen Scale:

I recently bought this [1]. It works with friction - you turn the nob once or twice and you're good to go for a couple weigh ins. It feels rather cheap - so let's see if it really lasts. I love the idea though. I wish we had more energy harvesting gadgets like this.

[1]; https://caso-design.de/en/p/caso-kitchen-energy-design-kitch...

When I was a child my parents had a purely mechanical scale, with a dial to adjust the zero.

Yet another case of why fix what isn't broken. Only, I expect that an IC or two and an lcd to run a digital scale are cheaper at volume than some amount of mechanical clockwork, once the cost of batteries is pushed off on to the consumer.

A quick glance at Amazon seems to confirm your intuition. The cheapest mechanical scale I can find is $32 but there are lots of electronic ones for ~$15.

We used to have one like that, too, and I don’t remember it being capable of single-gram accuracy like my cheap IKEA scales are.

Since scales inherently involve putting weight on them it should be possible to use that weight to push down a plunger generating enough electricity to run for the weigh-in.

A spring would then reset it for the next time.

If there's a plunger resisting the scale going down to harvest energy, that would prevent all the force from being on the load cell, giving you incorrect readings.

Not if the plunger rests on the load cell. Then plunger just captures the work done as it is compressed, it doesn't reduce the force that passes through it (once at equilibrium.)

Couldn't you subtract the resistance of the plunger and display the adjusted value?

You can put the switch in between the plate and the force sensor.

Then all the force is on the sensor and is also a switch.

Have had a similar model for like 5 years now. No regrets yet. The small effort it takes to power it up by far outweighs all of the disadvantages of a battery.

Before that I installed a switch in the scale we had to erradicate battery drain.

I love the idea, but the non-flat top, and the display on the flat top kill it (and admittedly, most cheap kitchen scales) for me. If I can't put a big bowl on it and still see the readout it's useless to me.

I haven't used one so not going to pick one to link, but a quick search finds scales that claim to run on ambient light.

Based on a 30 year old calculator I have, I would expect them to work fine.

Between clicking on/off at least once a day, and changing batteries once a year, I'm picking changing the batteries. I'd also guess most people would just leave it on. They may have already tried that.

I wish the Dymo label printer (for those labels printed on tape) had an off switch.

Every time I want to use it, the 6 batteries are flat.

Just remove one battery and it's off?

To be honest, I also have a Dymo label printer (very old model), and it does have a physical on/off switch, but even with the switch off it still consumes batteries like in 6 months.

I have one and didn't even know it could run on batteries. I've always used a power cord.

I gave up, bought the optional power adapter and just plug it in when I need to use it.

>Strangely enough none of our kids toys with batteries seem to suffer from this problem

we have some toys around where the way to turn it off would be to unscrew the battery compartment and take out the battery. The toy cuckoo clock that the kid broke that now goes cuckoo at odd times was fun, but hmm, nobody can seem to find it in the house anymore, wonder what happened to it.

Get Vernier calipers! The scale is easy to learn and use and measurements will be at least as precise as electronic calipers. With no batteries required the tool has much less of an environmental impact and you never need to worry about whether the calipers will work or not.

It's just the cheap no-name calipers that eat batteries. Genuine Mitutoyo (and probably similar brands) treat their batteries very kindly.

I have used vernier calipers but the time savings of not having to scrutinize the vernier scale every time you take a measurement is quite worthwhile. Just buy a good set.

> Get Vernier calipers! The scale is easy to learn

Yep.

> and use

Nope, not once you get old and tiny things are increasingly difficult to read with or without assistance.

Fair enough, usability will obviously be poor if the scale is difficult to read. My eyesight is terrible but at least it is still all myopia so I can compensate by putting the calipers extremely close to my eyes. Looks awkward and people call me Mr. Magoo but it works!

Yep, getting old sucks.

I just bought a digital caliper with a big LCD display. It will work with Imperial or Metric units, which I really like.

My analog calipers are Imperial. I love them, but run into Metric units a lot. Got those in '88 and they are still calibrating in spec and working great. No battery. Did need light oil and cleaning a decade ago.

I have one Vernier caliper and... it is getting hard to read in some conditions. Bummer. I still prefer these in longer forms, say greater than 12"

There are also calipers with a dial.

https://www.otelo.fr/waroot/images/products/600/40130350_A.g...

it doesnt even have to be a mitutoyo to get you down to 0.01mm precision, i got mine for about 40euros. Using equipment i had access to at work i checked that rating and indeed: the tool i got is good for measuring at that scale, and you really dont need any electronics.

Usually you can pay the vendor to calibrate the tool for a couple bucks more.

of course digital ones are much, much easier to read, but you only really feel that convenience when having to measure hundreds of items quickly to sort them into a tray or something...

And in the end, usually a Nonius type caliper is good enough anyways, and skilled users can read those to up to 0.02mm... and thats already pretty good and most of the time: good enough

and in case you do need to know the length of something down to a micron, there are other tools for that with less sources for measuring errors

so yeah: mechanical calipers rock and: you dont have to always get the brand things to get what you need

I keep a bunch of the US $16 stainless dial calipers lying around so I don't feel bad when I drop them or use them as a scribe. the mitutoyos only come out when its important - getting dimensions to make a copy, or the last pass on a part that really cares about it.

I have a very cheap plastic one with a dial, which works amazing well for the cost (<$10). I don't remember where I bought it, but it looks like this one: https://www.summitracing.com/parts/sum-900003

there are also 3D printed mods that add a switch

Could you check the voltage on those cells next time you swap?

I've found that seemingly similar devices have very different notions of what constitutes a discharged battery.

I have a remote controlled humidifier and RGB LED - controllers for which use one and two infrared LEDs respectively. Both are powered by CR2025 button cells, which when new have an open circuit voltage of 3.3V and 2.7V once depleted.

The two-LED device considers a 3V cell "dead", while the one-LED will happily work at this voltage.

Voltage doesn’t tell you much about the state of charge of a battery (especially with no load being applied), and there may not be much energy left at a battery ‘floating’ at 3V. The cutoff may have more to do with saving money on the power circuitry than what the designer thought was a ‘dead battery’.

No-load voltage is not the same as the voltage under load.

The two-LED device drew more current and thus the voltage dropped more.

Our kitchen scales have a single on button and auto power-off after a minute or so. I discovered completely by accident that holding the power button down for 3-4 seconds powers it off. Nowhere in any of the manuals was this mentioned (I went back and checked)

Many devices will turn off when you hold the power button long enough.

Maybe a rouge engineer added it for the benefit of mankind?

> electronic caliper: Same, eats up 1 button cell a year, just sitting in my toolbox

Had the same problem; got a good Vernier caliper, never looked back. Some things just don't need batteries!

I did the same! And now every time I go to use the thing I have to look up how to read it again.

I don't do highly accurate work very often, obviously.

I don't like buying non-rechargeable batteries, though, so cell batteries are out.

I agree. They're not difficult to read but they're definitely more of a pain than replacing a battery once a year.

A dial caliper is better than a vernier caliper anyway. Still more of a pain to read than a digital one.

I bought an RF pet tracker last year that comes with rechargeable CR 2032 batteries and a charger [0]. The rechargeable batteries factored highly in my decision-making process.

[0]: https://www.girafus.com/en/products/charger-batteries/

Also one sold by the Pi-hut: https://thepihut.com/products/lithium-ion-coin-cell-charger

After someone nicked my electronic calipers, I also got mechanical ones - they are perfectly adequate for all home use so far.

I used to use electric ones for 3D prints and designs, and haven't tries that since - might not be able to get the same perfect results with mechanical ones.

> electronic caliper: Same, eats up 1 button cell a year, just sitting in my toolbox

ooo a chance to plug one of my favorite youtubers; I believe it's this video [0] that compares cheap with expensive / brand digital calipers; the TL;DR is that the expensive ones use much less when off, or, the cheap ones use 4x as much. They both keep using power when off though, so that when you move the calipers while off it will still measure the distance.

[0] https://www.youtube.com/watch?v=KnDype-j3hk

This seems to be common in battery powered test equipment. I have a decade old Fluke multimeter and five year old Mitutoyo calipers that both seem to be powered by magic. Neither has needed battery replacement despite regular use.

When started to live in my own appartemen and was the first time sick, I bought a thermometer to measure fever. The second time when I was sick a couple of years later the battery was flat. So I bought an oldschool thermometer without battery to measure fever. I use still the same 20 years later. Of course it does take a bit longer to know your body temperature, but when you are sick, you are not in a hurry anyway.

I bought a Yamaha FX-500 processor in 1989. 29 years later, I did a mod to convert it to a batteryless NVRAM chip. The original button cell battery was still good; settings I last touched in 1990 were still being held.

Garage door openers can last 10-15 years too; those use the battery to transmit a signal, not just to hold a piece of SRAM alive.

The bathroom scale is just a poor electronic design.

Bathroom scales, kitchen scales and calipers all have versions that work without electricity and aren't much less convenient (if not more convenient since no waiting for electronics to boot up slower than they should or clunky menus)

I disagree. Measurements are funny things depending on the level of detail you need; analog versions of measurements are very clunky when you need precision. (now this is a bit much for bathroom scales and kitchen scales, but it was the calipers that interested me). When I need under .01 precision, my analog calipers just do not do the job as well as my electronic calipers. I can read them, but the last couple of thousandths are always sort of a guess. If I'm working on a project with tolerances of .01 or less, that's just not an option.

I guess a fun middle ground - I have a set of mechanical calipers with a readout in actual numbers on the side like electronics would, but all mechanical, like clockwork or whatever it is in there, going to .001. They're infuriating to use, because the numbers are so small on the side, and at that level of detail, stupidly sensitive.

edited the decimals because it's early and my brain shut off.

Is your caliper really that accurate and calibrated? In my experience you need a calibrated micrometer for that level of accuracy, especially to get a consistent measurements between several persons

Yes, reputable digital calipers are fine for thousandths of an inch. A micrometer is good for further precision and when you what more consistent measurements of softer materials. For example, if I measure my set of - gage pins, the caliper agrees exactly with the spec (a .210 pin reads 0.2095), and it's pretty hard to torque down too tightly on hardened steel. But if they were nylon and not steel, you'd probably get better repeatability with a micrometer. (And it's worth noting that the pins generally aren't actually half a thou smaller, a micrometer reads 0.20990. If 4 ten-thousandths of an inch are important to your project, yeah, you need a micrometer.)

ah, thousands of an inch, I'm not American and was thinking thousands of a mm

Yup. These calipers that measure to .0005 of an inch only show hundredths of a mm (10 microns).

As for language, "thou", short for thousandths of an inch, is kind of the base unit in imperial machining. That's why the next one down is "tenth" in the vernacular. It's very confusing because 100 thou is one tenth of an inch, but you'd never call it a "tenth" even if "inch" is implicitly the base unit. Also confusing is that there are SI prefixes for all of these things, but they aren't in use. (Why not "milliinch"?)

Finally, one more advantage of the metric system; to measure 1 micrometer, you need a tool called a micrometer. That's easy to remember!

Yes it is. It and my mics are calibrated to at least the thousandth. The shop has a 6" mic set on the ten-thousandth. But nobody uses that one because that's a level of detail that is just amazingly frustrating to chase.

>between several persons

This is just wrong. Rule one of precision equipment - do not touch my precision equipment.

Hum... Since I've brought a digital caliper that allowed reading sizes with actual 0.01mm precision instead of "guessing it's around X", I've noticed I have no object around that won't compress by something larger than that amount when I apply reasonable amounts of force into the caliper.

I'm also sure it's not calibrated to this level, but that doesn't hurt relative measurements.

That’s why calipers ought to have those tiny “rolls” that you can turn to move them, instead of pushing, this way you can’t “overtension”.

My analog ones do have a push wheel that slips easily.

The nice thing about analog is they don’t confuse you about precision - a digital caliper could be only precise down to .01 and yet show .0001 increments.

For many things like a bathroom scale precision isn’t really needed anyway.

Bathroom scales are one of the few devices where it's worthwhile to invest into a smart device with Bluetooth or Wifi

Regular tracking of your weight over years does provide valuable information about your health and no normal person regularly enter it into Excell

I try to never buy something that uses batteries and has a version that doesn't. My bathroom scale is a spring one. I do notice it isn't as accurate. The ones with weights are best, but those are quite expensive and take up a lot of room. For the kitchen I use electric for the extra precision while saving space.

My digital bathroom scale doesn't have batteries; it has a big capacitor and a foot-operated push-button that charges it. I tap the button maybe three times and that's enough energy to use it. It was also dirt-cheap.

I have a oven thermometer that has two active parts which are linked via some sort of wireless system.

One part is the one you plug the actual thermal probes into, and that then transmits data to a separate display. You can turn that one off.

Then there is the separate display that lights up and beeps and what have you: this one doesn't turn off, presumably so you can admire it say "--" whenever you're not actively measuring the temperature of something...

My caliper eats at least 1 battery per month and it's those awful R44 alkaline ones that start leaking when they're empty :(

I try to avoid coil cells in all my devices - all batteries in my house are rechargeable.

That being said, there are rechargeable button cells and there is a button cell charger!

https://thepihut.com/products/lithium-ion-coin-cell-charger

I had some digital bathroom scales, and I weigh myself pretty much every morning. The battery lasted a month, and those button cells are pretty expensive.

I decided to take it to be recycled and just bought a mechanical one. It was a little annoying at first as it's not as precise, but for my purposes that works fine.

Things that sit for much of the year I tend to remove the batteries when possible because I assume the batteries will leak.

It might not be true, but it feels like battery quality has gone downhill recently (especially AA and AAA). I had very few leaks from the late 90's to about 2015. Since then, a lot more.

This doesn't cover all the unwanted surveillance tools we pay to have spy on us.

Someone at my work has a really nice electronic calipers that is solar powered (think like a calculator… low enough power requirement that ambient light is more than enough) and thus will effectively never need battery change.

That is really clever, should really be used more often.

When it comes to kitchen scales, most Kenwood food processors double as very accurate and premium kitchen scales with backlight, as as they are plug-in they don;t need battery - great option if you have the counter space - you just place a platform where the chopping bowl goes.

After someone nicked my electronic calipers, I got mechanical ones - they are perfectly adequate for all home use so far.

I used to use electric ones for 3D prints and designs, and haven't tries that since - might not be able to get the same perfect results with mechanical ones.

My wife has a calculator that is solar powered--unfortunately, the light requirement to reasonably use the calculator is lower than the light requirement to run it.

Nice! I never thought about a solar powered model.

I may have to try one next time I am shopping.

You are thinking too big. The "power supply" is probably produced by some china factory they order it from

Factory A: Charges 7c per unit with a power switch.

Factory B: Charges 3c per unit with no power switch.

Wanna play the which choice did the C-Suite make game?

Button cells are annoying, as you can't get those as rechargeable.

I highly prefer AAA cells for those cases, you can get high-quality rechargeable cells from Ikea for a few coins.

All of those are ones I would argue the best design is to eat a few batteries a year. Calipers need to hold memory specifically.

But more generally most of those are using alkaleak batteries and you really wanna be changing those out on at least a yearly basis. So it actually makes since to let them have a small always on drain. (Some might be using a 2032 lithium but I can almost guarantee at least the calipers are a 357/lr44 alkaline battery.)

> Calipers need to hold memory specifically.

You don’t need power to retain a tiny bit of settings data.

I believe the real reason is because most of them have the “helpful feature” of turning on when you move it. Without something monitoring the sensor, no way to know to turn on automatically.

No, most calipers can only do relative measurements. It’s constantly counting how many 0.01mm the head has moved so it doesn’t lose track of where 0mm is located. Turning on the LCD when the volatile counter changes value is a free feature since the mcu is always on.

Of course better calipers do absolute measurements, but they’re too expensive to scribe lines with and therefore useless for hobbyists.

It is not just hobby people scribing lines. Just saying.

Memory of what?

Probably which position the zero is at, and maybe which measurement system you're using.

The zero set-point, usually.

The kids toys are probably all manufactured by VTech which has solved this problem once across all of their products

What's wrong with mechanical bathroom and kitchen scales?

I tried to get such a kitchen scale and couldn't find one that wasn't either highly imprecise or ridiculously expensive (like three digit euros)

If you have a vintage one that is reasonably exact, they're great.

You cooking meth there or something? It's a kitchen scale, I doubt you'd need that much of precision from it.

I use the kitchen scales (and a smaller set of digital scales) for measuring out things like resin where you do need a reasonable degree of precision, especially when you're measuring out small amounts e.g. 5g of A and 6g of B.

yep, also been doing that, mixing epoxy requires good accuracy.

that being said, UK police considers kitchen scales as evidence that you were dealing drugs

Ever tried baking with some of your ingredients 20-30% off? Doesn't work well for lots of recipes. What's even worse is when the error isn't a linear x%, but changes with increasing weight.

It comes down to the electronic design: specifically, low current draw when "asleep". Obviously it's possible to make electronics that costume a tiny amount of power (think quartz watch that lasts for years with a very small button cell). It's just poor workmanship by the designers or penny-pinching.