I, like many others, have digital calipers that drain the battery while sitting, and have no on/off switch, so the battery must be removed when not being used. I recall a conversation here some time ago about this and some had found different brands that worked better than others, in this regard.
Anyone recall the names of the brands that don't drain the battery?
Yeah. The expensive ones, like Mitutoyo. But you do need to use the silver oxide batteries, not their alkaline "equivalents".
I do have a Harbor Freight 6" digital caliper with an on/off button that (with silver oxide) doe last a long time when turned off every time.
Joe Gwinn
I don't, but that is the reason I buy dial calipers, I buy cheap, but stainless steel calipers (they make plastic dial calipers) . I misuse them by scribing lines, but that function is so handy, it is worth replacing a set occasionally. Mikek
The ones with an on/off switch! Actually mine just has an on switch and times out after a few minutes.
The good ones last forever. I like the analog display too.
I scribe lines on copperclad FR4 and that doesn't seem top dull the points. They could be sharpened too.
I suppose I was not clear as to my meaning by "on/off" switch. They typically have a push button to turn on. I've never seen one with a mechanical switch to directly disconnect the battery. Turning them off by the push button seems to only mute the display.
For the record, I got so tired of this problem that I bought a non-electronic one. There's a slight learning curve, but they're very easy to read to the nearest 0.1mm, and can do 0.02mm with a bit of effort.
Sylvia.
I have a dial caliper, but they are subject to damage easily and are hard to read if you have vision issues. I'm going to be needing good measurements in the coming six months and thought it would be good to have a digital unit again. I have one, but got tired of the battery running down or having to take it out each time I use it. I suppose I could leave it on the bench and only take the battery out when I clean up, but that might be a different decade. LOL
I just thought by now, there might be lower cost units that don't drain the battery. It's a damn simple circuit to implement that. I don't even think it requires a separate part. It's just a p-channel pass transistor with the switch as a bypass. Can't they put that on the chip and bring out a pin for the push button switch to bypass the pfet?
I guess it's a matter of them selling a bazillion of the ones they are making now. Why would they change?
But once one of the low cost devices starts bragging about not draining the battery, they will all have to switch. It doesn't take much sales pressure when you are only making a few cents per device.
Yes. The actual circuitry required is really simple. I think it's not included because if the thing is powered down, it loses its zero position (there are more advanced designs that have absolute positioning, but they probably cost more to make).
So it may come down to that. People would notice the loss of zero and complain before they realise that the batteries run down quickly.
For me, I'd probably zero it out of habit when I turn it on and not even notice the loss, but perhaps people differ.
Sylvia.
I can no longer see well enough to use vernier calipers. I still have dial calipers, and that works, but I've gone over to digital calipers that don't exhaust themselves between uses. They are just too convenient.
Joe Gwinn
Like you, I always auto zero calipers, including the dial variety if I'm trying to make a good measurement. It's hard to think anyone would expect zero to not drift, but many people don't understand electronics and seem to think digital is supposed to be as accurate as the display can indicate. That is seldom true.
What brand?
It does turn off the display and likely puts the MCU into deeper sleep. I have one of these, needs a new battery every 3-4 years, cost me something like $10 or $20, don't remember. Is quite accurate, I also have a micrometer (I do have a mechanical workshop, lathe etc. and I am quite experienced doing that sort of thing, too) and they match really well, if you know how to use it you can rely on it all the way down to its 0.01mm resolution. Keeping a blister of cr2032-s has you covered for at least a decade.
How long do you expect your battery to work?
Sometimes it's handy to "zero" the calipers on some standard part so a measurement gives the deviation, not the absolute length. If you went to lunch you wouldn't have your zero when you came back :-).
To work? A few weeks at least. When off? Years, or as long as the batteries last sitting on the shelf. I don't know how long they actually last. Every time I put it away without removing the battery it is dead the next time I use it. I don't have a battery at the moment, so it's useless. It uses the smaller battery. I might have a pack of those somewhere, but I don't care. If I can't find a digital caliper that will not run down the battery, I'll just get a pair of head mounted lenses and use the dial caliper.
I do know better than to ever use a Kirkland (Costco) battery again. I had a batch of AAs that ruined a half dozen pieces of equipment. Costco wouldn't even refund the purchase price.
to be as accurate as the display can indicate. That is seldom true.
You mean like
Yes I have been using them on a project lately and one point is dull, I looked it over and decided it can be sharpened without affecting accuracy. I'm in the market for a new one as the one I have has a problem, sometimes it zeros at a zero sometimes at 0.004". Probably something got in the gear track, but I don't see it. I've had them close 10 years, I got my money's worth out of them, $15,99 at Harbor Freight. Now there $29,99 and I never see them on sale.
Mikek
Mitutoyo is a high quality brand. But be aware that there is a very large number of fake copies on the market. If you get the cheapest one form Ebay, you WILL get a fake.
James over at the "Clough 42" Youtube channel has made a video where he looks at some differences between the real and the fake ones:
Take the dull one home. They are great for home shop use too.
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