Thread: Question about battery life in digital calipers

Originally Posted by familyguy

I have some digital calipers (about 7-8yrs old) that seems to have a short battery life, the LR44 cell lasts about 2-3 months and always seems to go flat just when I want to use it. Is mine just an old design or do newer calipers have similar short battery life, the LR44 cells in my workshop calculator last 5 yrs or more.

I have 2 digital calipers, one is a black plastic one from bunnys in which the battery lasts for about 2 months and a SS one where the battery lasts for 12 months. They were like that from new.

At work we have dozens of the SS variety and it's a lottery, most batteries last for more than 12 months but some only last 3 months. Some get worse over time one even got better! The techo at work reckons they get dirty and leak small currents even when switched off. the ones that get worse he usually takes them apart and cleans them out with compressed air with mixed results. When some of them stopped working, he soaked these in meths, for a couple of hours, moving the mechanism back and forth every few minutes, and then let them dry out for a week, put a new battery in them and they came good. if you decide to try this, remember to remove the battery before soaking! He said this appeared to have improved the battery life as well.

hi
My understanding of it from the American machine shop sites is that the battery in the caliper is continually on.

The on /of function merely switches the display on or off.

The LR44 alkaline battery is the way to go as it last longer than the alternative (I forgot the code no for it).

I guess I get about 12 months of life from a somewhat infrequent use.

Grahame

Same thing happens with most LCD display machines...like Wikey Angle gauges etc

I use digital verniers all the time as well as DRO's on my machines. Best I have found is to buy 50 batteries for about $8.00 to $10.00 Aus delivered that way you never get caught with a flat battery. Look for the alkaline ones and they are as good as the name brands.
http://shop.ebay.com.au/?_from=R40&_...All-Categories
If 50 is too many be generous with your friends.

Originally Posted by Grahame Collins

hi
My understanding of it from the American machine shop sites is that the battery in the caliper is continually on.

The on /of function merely switches the display on or off.

The LR44 alkaline battery is the way to go as it last longer than the alternative (I forgot the code no for it).

I guess I get about 12 months of life from a somewhat infrequent use.

Grahame

Grahame,
My experience has been a longer life from the silver oxide equivalent SR44 battery. They are more expensive than the Alkaline LR44, costing $1.80 each from Jacar, as against $1.40 for the LR44.

Originally Posted by Chas

Grahame,
My experience has been a longer life from the silver oxide equivalent SR44 battery. They are more expensive than the Alkaline LR44, costing $1.80 each from Jacar, as against $1.40 for the LR44.

I use the silver ones but never get more than 12 months out of them.

My Mitoyoto digital vernier has been going for over 3 years so far and still has the original battery. I don't think the thing is on all the time (just switching the display) as EVERY time I switch it on, I have to rezero the thing now.
Cheers
Graeme

If they specify SR44 battery as do the Mitutoyo then do not use LR44. There is a huge difference in battery life. I tried the LR44 and they just do not work properly in the Mitutoyo.

Nev

Hi Guys,
Chas was right ,
I went and had a look inside the battery case of my calipers.It was an SR44
Originally I started on L44's.and read the thingy in the yank engineering forum and changed them.

I looked in the tool box and the empty pak for the L44 was there.

Ooops!!!
my apology and thanks for setting me straight on this.

Ta
Grahame

Wixeys' can be easily converted to run off 2xAA rechargeable batteries - I posted a DIY here over a year ago.

I think with the calipers you probably have to take the battery out if you are leaving it for a while - I also think some of the fitted cases may press all of the buttons, haven't got round to excavating the foam in the case of my good set yet as the cheap, caseless plastic ones seem to work OK.

Maybe I should just set a set of dual measuring dial readout calipers from Lee Valley - no batteries.

Originally Posted by bsrlee

Wixeys' can be easily converted to run off 2xAA rechargeable batteries - I posted a DIY here over a year ago.

Would AAA batteries work with the Wixey?

If I leave the batteries in mine they are always flat. I just take the batteries out when I put it away.

AAA's would also work, but they have about 1/3 the capacity of AA batteries, and usually cost more. Also they are not available in the new 'low self discharge' format. The battery box needed for the conversion is available in AAA & AA versions, same price IIRC.

The 'calipers are on all the time' rumours are true, I actually went and measured them one day.


I measured the steel ones, and when ON they draw 12.5 micro-amps (0.0000125 amps) and OFF is 10.5 micro-amps (0.0000105 amps). Yep, all they do is turn the LCD off. That small power difference is like lasting a year versus a year & two months.

I've got a pair of the composite/plastic ones as well (maybe 5 years old). These ones I have don't have an on/off button, but do have a depth gauge, thumbwheel, lock and data port like the steel ones. The big difference is the display, the composite one is tiny, the number are about 6mm (1/4") while the steel version is almost 12mm (1/2").

The ON current was about the same as the metal ones (12.5), but varied between 12.1 & 12.9 micro-amps. Eventually they shut OFF, and the current stayed about the same. Well, now it flickered from about 11.9 to 12.3 micro-amps. I initially thought they really did turn off, but my test lead had fallen off (doh). Looks like the small LCD draws very little power.

So these (or my version anyway) will chew up the battery a bit faster.

Both versions remembered the last value, which makes sense as they never really turn off.


An LR44 battery has a capacity of 100-150mAh, depending who you ask. The number is a bit rubbery anyway, you need to check the datasheets to see how they tested the battery, and you're not going to get one from your typical eBay seller.


Using the 100mAh rate and the ON current of 12.5 micro-amps, the battery should last around 8000 hours, or about 11 months. With the display off a couple of months longer.



So in theory you should get a year out of a fresh battery. If they really did turn off then the battery would last forever. (1 hour per day @ 8000 hour is 21 years, not quite forever but you'd have lost them by then anyway.)