No, the unit is on all the time, it just does not take that much power but if you don't use it much it'll be dead when you need it, remove the cell and put that in the case when done..
You get what you pay for however, if you use it all the time then you'll get full use of the cells.
- I have two digital calipers. One is an inexpensive Chinese-made model, purchased from Harbor Freight for somewhere around $20 (might even have been $15 on sale). The other is a Japanese-made Miyotoyo, purchased (used) via eBay for around $90.
- Both models use a single LR-44 alkaline battery (or, alternatively, an SR-44 silver-oxide battery).
- The two models are of essentially identical physical sizes and have similar capabilities.
- The two models are stored under essentially identical conditions (a foot or two apart, on a shelf in my garage).
- I always turn the displays off with the "on/off" button when putting them into storage.
- After I bought the Chinese model, I found that it would consistently "kill" a fresh LR-44 battery within a couple of months, even if I didn't use it at all. The caliper would power up when I pressed "on" but would almost immediately begin to flash its display with a "low battery" warning. Since I use it infrequently I always had to plan to put a fresh battery in for each use.
- An SR-44 battery lasts significantly longer in the Chinese model (higher capacity and a flatter voltage discharge curve, I believe) but the caliper will still kill the battery within a few months even if the caliper is stored "off" and not used.
- I don't know how long a battery will last in the Miyotoyo. I bought it two years ago, put in a fresh battery when I received it, and that battery is still running it.
My inference: the "standby-when-off" current drawn by the Chinese-built Harbor Freight caliper, is higher (probably a lot higher) than the current drawn by the Miyutoyo caliper.
I have heard the same story told by quite a few other people.
This isn't to say that *all* Chinese-built calipers are "battery killers". It's entirely possible (and I suspect it's very likely) that some models, from some OEMs/factories, are a lot better in this regard.
The hard problem is figuring out which models (of the many types on the market) are good ones.
For some reason the fractional dial calipers are significantly more expensive than the metric and rarely go on sale at HF. I finally gave up on the digital calipers a couple of years ago and bought one. I don't abuse it (much).
I have several tools that use digital caliper mechanisms and they all kill batteries. Taking them apart to take the batteries out after every use isn't going to happen.
I think someone is suggesting that if you don't close the calipers and turn them off and back on, they will read zero if they truly powered off while the ones that remain powered when only the display is off will retain the setting. Or better yet, turn it off, move the calipers and turn it back on. If the displayed value is still correct, the unit never turned off. I think I did this once and found my caliper was running all the time. I haven't used either of mine for some time now, but I think I eventually started removing the batteries when putting them back in the drawer.
The micrometer and dial caliper, on the other hand, both work all the time no matter how I store them.
I didn't know they sold tools and such. I was only in one a couple of times. I didn't seem much of interest and left. I remember the last time I went I tried to get a cart and found I needed to deposit a refundable quarter to get a cart. I didn't have a quarter on me so I went to Giant. lol Haven't been back since.
The crappy plastic ones would be pretty dubious. They're okay for measuring a '2 x 4'.
And correct for insulation. Really, resistance is a pretty good idea, assuming you're sure it's really Cu and not something more exotic.
If it's not copper colored *when stripped* and seems unusually springy, be suspicious.
--sp
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Best regards,
Spehro Pefhany
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Microchip link for 2015 Masters in Phoenix: http://tinyurl.com/l7g2k48
Some telco-style wire is seven strands-four of copper, three of stainless steel; there's also steel-core copper-exterior, but that's usually not tenth-millimeter size. The central wire of RG-59 (CATV cable) is magnetic but copper on the outer surface.
OK I got a chance to look at it again. I think it's just tinned copper. It has extremely thin insulation that made it look like some other metal with a satin finish. Not CCA, CCS or any mystery form of resistance wire.
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