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Digital caliper current draw, offshore vs. Mitutoyo

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  • Digital caliper current draw, offshore vs. Mitutoyo

    I checked the current draw on a couple of calipers. Interesting results; the difference between on and off is about 2 microamps. That's what the LCD is drawing, otherwise the calipers stay "ON". The current draw on the cheapos is insanely high! Here's the vid:


  • #2
    fantastic! very cool. real numbers beats conjecture every time. Now I know for sure what's going on when I was suspecting about my cheap calipers vs my good ones, with the measurements going crazy at some unexplainable point.

    One other thing I seem to have noticed varies but never fully tested with a proper method is temperature compensation. My cheap ones will be a couple thousandths off between a hot and a cold day compared to the Mitutoyo's. That whole effect where resistance and capacitance change with temperature needs to be compensated for in many types of digital measuring tools, like scales. I know of one shady jewler that's used a cheap temperature-vulnerable scale to make a few bucks buying gold.

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    • #3
      Think, BMW, to get to work.
      Think Mitutoyo, once there and get'n down to Bizness.

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      • #4
        I really appreciate the confirmation of why my Mitutoyo calipers use so few batteries.

        If you ever get the chance to check a Starrett, I'd bet they're right up there with the Chinese no-name ones in terms of power consumption, or worse. They use a relatively huge battery and it doesn't last but 1/5th or less of the time a little SR44 does in my Mitutoyo.

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        • #5
          Originally posted by digiex_chris View Post
          One other thing I seem to have noticed varies but never fully tested with a proper method is temperature compensation.
          That is a great question! I'll look into it.

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          • #6
            This was written up some years ago - either here or at PM, or perhaps even both. I learned of it by example since the second time I went to use any digital instrument I was always met with a dead battery. I finally decided I prefer non-electric instruments and I especially like my dial calipers though it would be nice to easily convert between imperial and metric

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            • #7
              My Mitutoyo and B&S calipers and mics last years.. so many I can't remember ever changing batteries. I had a set of "SPI" (import) mics.. maybe 6 months.... sold those.

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              • #8
                That's an awesome review of a common issue with Digital Calipers.
                Thank You Superunknown....

                I would say that both my Mitutoyo and Fowler (both Japanese ) have great battery life !
                My old Starrett 722 is a fantastic Digital but also used lots of power when sleeping.
                Having a 200+ dollar inspection tool that reads in tenths ( yes, .0001) was worth having so I modified it
                and will post the pics here , when Photobucket gets back on line.
                I am not sure if the solution will work with current imports, but it is a simple technique to dramatically reduce battery changes.
                Rich
                Green Bay, WI

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                • #9
                  I did the same test on my older (better) HF calipers some years ago, and I think the current readings about matched those in the video. The LR44 battery has about 150 mAh and the SR44 about 200 mAh. So 20 uA should result in about 10,000 hours or 1.14 years. I have recently found on-line sources for these batteries for about 25 cents each so I don't mind changing them. My older calipers blink the display for a low battery condition, and turning them off just blanks the display and drops current by about 20%, but holds zero. My newer cheapo from HF has auto-shutoff and you must re-zero. I haven't tested my newest HF calipers which also have fractional reading, but they do hold zero when turned off.
                  http://pauleschoen.com/pix/PM08_P76_P54.png
                  Paul , P S Technology, Inc. and MrTibbs
                  USA Maryland 21030

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                  • #10
                    I accept that my batteries in my digital stuff - micrometers and calipers - regardless of whether they are "Starrett" or "Off-shore" - will use up battery power albeit at varying rates.

                    I just accept it as part of the cost of having them and so as changing a battery is only a minute or two of time I replace the battery if/as required and get on with what ever I want to do.

                    Battery cost is of no concern here - probably dearer than in the USA - and provided they don't leak I am OK and up and running again in next to no time at all.

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                    • #11
                      It could be that variation of accuracy with temperature could be due to the effects of temperature co-efficient of expansion (or contraction).

                      It can easily be countered by using the caliper to measure a know-size object (at room temperature) and noting the difference and allowing for it.

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                      • #12
                        I have a Mitutoyo quill readout on my vertical mill. After looking at some photos of some millwork from a while ago, I realized I'd had that readout on the mill for over ten years... And I think I've replaced the battery in it once. Maybe.

                        I also have a set of the usual cheap import calipers- $24 at O'Reillys' auto parts years ago- and those things have a blinking display (low battery) pretty much every time I pick them up, it seems.

                        Just proof again you pay for quality.

                        Doc.
                        Doc's Machine. (Probably not what you expect.)

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                        • #13
                          Well, if it were me and knowing that I'd have to change the battery I'd make it part of my start-up procedure - only a couple of minutes and less that 1$ per time.

                          Its all to easy to be "too aware" of the "time" you save without considering the time and consumables costs without going over-board into "penny wise and pound (UK) foolish" territory.

                          A cost-benefits analysis might render a few surprises - but put a realistic value on your time ($60US per hour = $1US per minute?).

                          For me, batteries are "consumables" and just part of the every day cost of running a shop - same as electricity and welding rods and gasses etc..

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                          • #14
                            I was going to say it's also 'pound foolish' to buy the cheap batteries, but in this case, it's probably one of the highest and best uses for cheap no-name cells. For the Mitutoyos, though, I buy the good stuff- yeah, they may be $4 retail from the grocery store, but I think $4 every ten years on the quill readout, and another $4 over the past 5 years or so I've had the calipers, is a small price to pay.

                            Doc.
                            Doc's Machine. (Probably not what you expect.)

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                            • #15
                              I buy 4 packs of LR44's at the local dollar store for $1
                              So I really don't care anymore how long my caliper batteries last.
                              Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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