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I'm finding that the standard AAA battery from most manufacturers (including Duracell and Energizer) have gotten shorter and don't fit as tightly in my alarm clock and HP-48 calculator. The old Duracells (I dated these as 2015 when I inserted them) fits tightly but the new ones drops out.

Has the standard charged or is this a case of shrinkflation?

Null
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D Duck
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    Or is it your spring that's moved? I've not noticed any problems with any of my AAA batteries. – Puffafish Jul 07 '22 at 08:10
  • Nope. As I have two HP-48 both with the same problem. Old batteries are tight, new ones aren't. Put the old ones back and they're still tight. Alarm clock has the same problem but it isn't as well made as the calculators. I'm not looking for a solution to the loose battery but asking about a possible size change. – D Duck Jul 07 '22 at 08:32
  • The AAA standard was delcared in 1959, I can't find any evidence of it changing. Possibly a tollerance of the length measurement (nominal 44.5mm), but I can't find any tollerance bands supplied in the standards I have access to. – Puffafish Jul 07 '22 at 08:54
  • What is "shrink flatiron" exactly? – Finbarr Jul 07 '22 at 10:22
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    @Finbarr I suspect it's an automatic spell checker mangling an attempt at "shrinkflation". – Simon B Jul 07 '22 at 10:29
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    Can you measure old and new batteries with calipers and see if the length really is different (and post the measurements)? – TypeIA Jul 07 '22 at 10:36
  • According to [this diagram](http://www.batteryholders.org/aaa.pdf) the length is 44mm with a tolerance of +/- 0.5mm. So two different batteries could be 1mm different but it's hard to believe the spring contacts wouldn't be able to cope with that. – Finbarr Jul 07 '22 at 10:57
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    [do old batteries enlarge](https://www.google.com/search?q=do+old+batteries+enlarge&rlz=1C1ONGR_en-GBGB999GB999&oq=do+old+batteries+enlarge&aqs=chrome..69i57j0i22i30j0i390l4.6499j0j15&sourceid=chrome&ie=UTF-8). – Andy aka Jul 07 '22 at 11:27
  • Plus 1 for the HP-48, still have mine and the 28s. – Solar Mike Jul 07 '22 at 12:35
  • @SolarMike try some new AAA in your HP-48 and see if the middle battery is loose. The top and bottom are ok as there is enough motion on the contacts – D Duck Jul 07 '22 at 12:38
  • Middle battery not loose, but the foam backing the springs is still spongy and the batteries (Duracell, BBE 2029) bought 2 months ago measure just under 44mm but more than 43.5mm. – Solar Mike Jul 07 '22 at 12:46
  • All my batteries here are almost exactly 44 mm long. The longest I can find is 44.1 mm. Is this an issue of quality control being able to make exactly the same size battery and the equipment was designed to accept the mean sized battery of the time which was slightly longer? – D Duck Jul 07 '22 at 12:56
  • Seems odd to close this question - if batteries are changing in dimensions that would be of importance to someone making electronic devices. – D Duck Jul 07 '22 at 16:29
  • Absolutely the standards have not changed. There's a surprising amount of tolerance in them however. – Kyle B Jul 08 '22 at 04:09

1 Answers1

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I don't think so. Current batteries (Amazon, Panasonic, off-brand that came with something) measure very close to 44mm (don't forget to add some insulator if you use metal calipers or a micrometer, lol, then subtract off the insulator thickness).

Springs on handheld devices, if poorly designed, can have their yield point exceeded if the device is tossed around or dropped, which permanently shortens the spring. Ideally a molded stop would prevent that. Stretching the spring out past the yield point fixes it, until the device is dropped again.

  • 44.07mm off-brand
  • 44.16mm Panasonic Alkaline plus
  • 44.37mm Amazon Basics

Duracell:

enter image description here

Rayovac:

enter image description here

However note that Energizer has a lower interpretation of the IEC standard by as much as 0.2mm.

enter image description here

If we go back and actually reference the 1959 standard, the maximum dimension for AAA cells is given in metric as 44mm, but in Imperial as 1-3/4", which is 44.45mm. The minimum is given as 43mm or 1-11/16" which is 42.86mm.

ANSI C18.1M, Part 1-2001 ($$$ standard) specifies the length of an AA cells as between 43.3 and 44.5mm, same as Energizer.

So they've tightened up the specifications a bit. If you took the metric dimensions in the 1959 standard as primary (nobody would have at the time) the cells have actually grown a bit.

Spehro Pefhany
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