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Comment by shimonabi | Hacker News Reader

If you leave the battery inside a cheap caliper, the battery will be dead in a couple of hours, even if the caliper is switched "OFF".

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You're right but way off on timing. These common digital calipers have a design error which does in fact drain power while off, but it's nowhere near a couple hours. They reasonably should last several years but in reality it'll be on the order of 6 months or so.

i don't know if i'd call it a design error but it is a cheaper design to manufacture than the more expensive kind that requires calibration. could also be a patent workaround. for something like 10 bucks many years ago i got some nice stainless 12" ones that work fine other than the lower battery life thing. they do lose track if the battery is low though and you move the jaws quickly. just have to have a bunch of batteries on hand and/or take the battery out when not in use.

What's really annoying is that they could have sidestepped the whole problem by simply putting a simple physical on/off switch on them, instead of the soft on/off button they use. No one uses these cheapo calipers for more than a few minutes at a time anyway, so the battery would probably last a lifetime with a normal switch and no one would notice that it's a power hog.

> simply putting a simple physical on/off switch on them, instead of the soft on/off button they use.

that's true but a physical switch needs to be placed and soldered while the soft on/off just needs to be placed atop it on the traces on the pcb. cost just probably was the biggest issue.

There may be different levels of "cheap".

I bought a €20 digital caliper (this one[1]) and the battery is still fine, 2½ years later.

[1] https://www.bauhaus.dk/alpha-tools-digital-skydelaerer

This is obvious BS. Many of them get packaged and shipped with the battery in them.

That said, they absolutely do eat batteries faster than the expensive calipers.

It's not. I take the battery out after each use. Several users have reported this, for example:

"Turns out they pull almost as much current off (15uA) as they do on (17uA)."

https://www.reddit.com/r/harborfreight/comments/z7j8hp/fixed...

An LR44 supplying 15 microamps will last more than 9 months before depleted. This base level of current draw obviously matters to different users differently.

Possibly not if you buy the LR44 from Amazon. I have gotten batteries labeled "LR44" that were practically useless. I've also gotten "SR44"s that were actually LR44s.

I think the worst offenders are the ones that use the measurement circuit to detect if you've started a measurement while the display is off.

my $10 Harbor Freight calipers are still on their original battery after 8 years. So I'm not sure about these claims about being constantly on and draining the battery. I think instead that you have to have them fully closed when you power it on so it can zero out. It also has a button to zero.

It definitely depends on the model. In my experience, my cheap calipers from Harbor Freight run for far longer before needing a new battery than my cheap calipers from Home Depot.

Not all of them. I can recommend this one, it has long battery life, good precision and smooth mechanics: https://www.amazon.de/gp/product/B002JU64F4/

That looks very similar to one I use that typically gets about 2 years of battery life.

A model that looks exactly the same costs 5€ on Aliexpress. I don't like to be ripped off.

Got a link? I mean they all look similar, tried a cheaper one before but it was crap.

https://www.aliexpress.com/item/1005004683435276.html

https://www.aliexpress.com/item/32985627216.html

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