HF digital calipers battery usage/life

[LCHIEN]

Yeah so I've been wondering about this for years.

I like the HF digital calipers - they are cheap and very accurate.
For the most part they are smooth running and comparable in accuracy to the $150 Mitutoyos at work.
The bad thing is that battery life - they seem to go through batteries fairly quickly. I have 2 or 3 pairs in the shop for use and another inside the house.

I did have one that was for the most part intermittent - got worse and should have returned it. Another I had bought on sale and had not used had a real rough running slide.
So I spent a couple of hours messing around - the intermittent one had a battery lead that just pulled off when I tugged on it - unsoldered. I resoldered it but it was still quite intermittent.
I finally took the electronics off and tossed it and used the electronics from the rough running one and mated them to get a perfect set.
So I saved $10 with a hour or two work! At least I learned some things.

One thing I did learn was about the limited battery life.
It didn't seem to last that long but I have been using the carded LR44 batteries off eBay, ten for $1.99 or $1.29 or so with free shipping. Bad batteries? excessive drain?

So I put my good electronics meters on it.
Seems it draws 22 uA whether it is on or not. In other words, turning it off saves virtually no power. I tried two different ones, same result.
So An LR44 is rated 150 mAh. That means a good battery should last about 6800 hours at 22 uA.(9 months).

So

• the cheap 20 cent batteries I get are not so bad.
• you are not saving anything by turning it off
• they will theoretically last less than a year continuously ( 9 months) if you don't take it out of the socket.They will last a whole lot longer if you want to go to the trouble of taking it out of the unit.
• I get about 6 months it seems - maybe that's the 20 cent battery penalty; not as good as a name brand battery that costs $3.50 at the retail stores..

So if I leave the battery in it, it costs me about 20-30 cents a year to power it.

But anyway that's why I get short life (less than a year) from the batteries.

[thrytis]

Thanks! These days I don't use my calipers very often. I'll take the battery out so I don't have to replace them every time I do use them!

[capncarl]

I did not have any idea that these devices were powered up the whole time! I suppose all the power button actually does is turn the display on and off then? 1 year is about all the time I get get out of my caliper batteries as well. Do you suppose this battery always on situation also holds true for other digital measuring tools as well? As well as the digital calipers I have a off brand Wixley cube shape angle finder, a Wixley angle finder and my favorite, a craftsman digital miter gauge. All but the craftsman digital miter gauge they all use button batteries, and each a different size, and all seem to die at about 1year! The craftsman digital miter gauge uses 2 AAA and they seem to die quicker. It has an easy to get to battery door so I just pop it open and take them out between each use because ive had bad luck with AA and AAA leaking and ruling the device.
What are your thoughts on better or more expensive button batteries? Any real difference or just in a more expensive blister pack?
capncarl

[LCHIEN]

I did not have any idea that these devices were powered up the whole time! I suppose all the power button actually does is turn the display on and off then? 1 year is about all the time I get get out of my caliper batteries as well. Do you suppose this battery always on situation also holds true for other digital measuring tools as well? As well as the digital calipers I have a off brand Wixley cube shape angle finder, a Wixley angle finder and my favorite, a craftsman digital miter gauge. All but the craftsman digital miter gauge they all use button batteries, and each a different size, and all seem to die at about 1year! The craftsman digital miter gauge uses 2 AAA and they seem to die quicker. It has an easy to get to battery door so I just pop it open and take them out between each use because ive had bad luck with AA and AAA leaking and ruling the device.
What are your thoughts on better or more expensive button batteries? Any real difference or just in a more expensive blister pack?
capncarl

Like I said, I buy the 10- packs for (the one that just shipped was $1.29) since I have so many things that use them. I think they are much more economical that wasy even if they last only 2/3 as long.
You can buy "eveready" and "Maxell" on eBay but I suspect they are counterfeit. But so many toys, laser pointers, keychain LEDs and other blinkies are sold using LR44s that they are really cheap.
You can buy them in the 1000's for 6 cents apiece I found.
Here's the $1.29 ones free shipping: http://www.ebay.com/sch/i.html?_from...=LR44&_sacat=0

About shut off, these type of electronics need to have at least part of the circuit always running to detect the pushbutton on states. Also they remember the zero location and mode when off. So there's some part of the circuit alive always.
It may be that the measuring part is so low power so that there's not much savings when the unit is "off".

[tfischer]

Yeah we get the cheap button cells off of ebay. Most things I have use CR2032's but we buy the 44's in bulk too. Also Northern Tool cells a card of cells in like 8 different sizes for those oddball items.

Can't be without my calipers lol

[cwsmith]

Loring,

Thanks for the analysis. Who would have thought that the 'on/off' switch did not function to cut the power drain; certainly not me. However, I did note that the battery drain problem, just didn't know whay. So, After my first experience with these I just started taking the battery out as I don't need calipers on even a weekly basis.

I have a 7" vernier which I bought back in 1964 when I was a mechanical inspector and thus are my preference for their smoothness (the HF that I have is rather rough). However, the eyes are not nearly as good today, so those HF calipers come in really handy when I have such needs.

I have a digital protractor (angle gauge) that uses a CR2032 and it suffers similar battery drainage problems. Again, the battery needs to be removed between those rare occasions of use.

Thanks again,

CWS

[capncarl]

The HF calipers are not only cheap the are tough. I purchased a couple of the to adapt into on of my finger joint jigs. Online someone used one like this but built a wood attachment for the caliper and another wood attachment on the moving part. it wasn't convenient to mount the blade in wood so I decided to drill a hole in it and attach it to me moving part with a screw. I have about every type drill bit available and fastened the caliper in my mill machine vice so I could control the drilling properly and use coolant. I think I burned up 4-5 bits trying to drill blade, the final bit I used was one used to drill hardened armor plated vehicles. I don't know what they are made of but it is some really really hard stuff.

[Bill in Buena Park]

Good post Loring. I saw a video somewhere on this, they found the same thing - battery draw even though "off". So on my model, there is a little tray the battery sits in that can be partially ejected - and that was my solution; I partially eject the battery when not in use, which eliminate the draw-down.

[LCHIEN]

Loring,

...

I have a 7" vernier which I bought back in 1964 when I was a mechanical inspector and thus are my preference for their smoothness (the HF that I have is rather rough). However, the eyes are not nearly as good today, so those HF calipers come in really handy when I have such needs.
...

CWS

Yeah, always try the calipers before you take them home. Some are very smooth and some are rough like they didn't clean or deburr the cut areas. The smooth running ones are very nice.

I had some vernier analog dial calipers I got and the darn thing broke - the case extended into a point where the thumbwheel mounted and it broke and the thumbwheel fell off. Now its hard to use. Rockler, I think.

[cwsmith]

I bought my old Vernier back in the spring of 1964, soon after high school. I had landed a job at a local manufacturing company as a mechanical inspector because I could read micrometers (a lesson from high school shop class, it got me ten-cents more an hour, $1.35 when the minimum wage was $1.25.) These are hardened stainless with a satin face and the scale reads out to 9 inches, though you can only measure to about 7-1/4. They have an additional slider that you can lock in place and use the thumb-wheel to fine adjust. They came with a leather case and are marked 'MODERNTOOLS MT-13B' I don't remember what I paid for them, but they were expensive at the time, costing me several days pay.... but what didn't way back then. Love them, but without 'close-up' glasses it's impossible to read these days.

I had tried a couple of the HF calipers and they both seemed rough. Just should have investigated further, but these work and, as you mentioned, the accuracy is very good.

Thanks,

CWS

[LCHIEN]

Played with the calipers - latest ones, and while its not important, I was curious after previous comments.
Apparently the measuring circuit is always on - which means primarily the on-off switch controls the display. LCD displays, the 7-segment kind with no backlighting use essentially no power so that's why the power doesn't change.

I tried moving the calipers to a known value (say 100 mm). WHen I turned them off and back on it said 100 mm.
When I turned it off and then moved the head, it immediately turned on the display and went to the correct measurement.

So the conclusions are:

• It always keeps in memory the mode, zero and current positions
• its always measuring and detects any movement to turn on the display and display the updated measurement
• toggling off the power push button essentially turns the display on and off.

So that's why it uses full current all the time, although admittedly its a small current.It's enough to consume the battery in 6-9 months.whereas the battery shelf life by itself should be 5-10 years.

[capncarl]

I just received the fractional calipers I ordered. They came with a battery installed. I wonder how long the battery has been in the tool? This post made me thing about my other calipers, my everyday pair and the spare pair still in the unopened box that I ordered 3 years ago for a project. I opened it to check for a battery installed, yep, it came with a battery installed, and it still works. At least 3 years old battery! I did take it out, maybe it will be ok when I do decide to use it. I also found the batteries in my Wixley dead.
Thanks Lchien for pointing this battery fact out!