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Tube❄️Time

fun fact! the numbers in coin cell part numbers are dimensions. a CR2025 is 20mm diameter and 2.5mm thick!

a digital caliper measuring the thickness of a coin cell (2.5mm) but the caliper is made of metal, obviously shorting out the coin cell.
36 comments
Eli the Bearded

@tubetime I have known this since forever (well at least the late 80s). And the CR part refers to the particular chemistry.

I learned it from this book or some similar Radio Shack book.

archive.org/details/enercellba

Alex Willmer

@tubetime also true of cylindrical cells. An 18650 cell is nominally 18 mm diameter by 65 mm long. AA cells are sometimes called 14500, nominal 14 mm dia. by 50 mm length.

deBaer

@tubetime That works for most batteries. An 18650 LiIon round cell is 18 mm long and has a diameter of 6.5 mm. A 704044 LiPo pouch cell is 7.0 mm thick, 40 mm wide and 44 mm long.

Darryl Ramm

@tubetime What is all this God damned metric shit? 😉

Tube❄️Time

too thick? it's easy to compress it in a vise, like so.

a coin cell in a metal vise. uhhh please don't do this
DELETED

@tubetime

I hope you didn't create a short circuit there.

Franz Graf

@tubetime @nikcorg
😳 Damn, I always wondered but never checked the origin of the numbers

⁂ Shevek ⁂

@tubetime Be careful not shorting the electrodes!

~n

@tubetime ...and it all goes up to 2477 which is a whopping 24mm x 7.7mm and packs up to 1Ah which is six times the capacity of a CR2025. So... If your project demands 3V, but an e.g. 2032 won't last enough... at the expense of some height there are other single cell options. They are less common but they are almost as widely available as the more common ones.

Peter Schmidt 🦈

@tubetime
this picture makes me pain because of short circuit the poor cell

Cegorach

@tubetime works for Lipo-Cells and similar too…

i.e. 18650 - 18mm * 650mm

or 26650 is thicker

Colin

@tubetime @DosFox yep, same with 18650s etc. diam X length.

Also it’s fun when you don’t have quite the right size button cell but if you do have something that could nominally fit and still make it work!

gafu

@tubetime
For CR type battery coin cells only

The little AG, LR types do have weird numbers related to the manufacturer and chemistry.
4+ different names for same size

UpLateGeek

@tubetime you can also measure the coin cell voltage with your (metal) digital caliper, just press the “zero” button and you’ll get a reading in volts.

Johannes Spielmann

@tubetime Oh, are we doing "things everyone should know but no one ever tells you"?
Here's mine: there are two different kinds of "cross head" screws: Philips and Pozidrive. Pozidrive has the little diagonals, in the screws and in the drivers. The sizes are (of course), ever so slightly different, and the drivers will fit MUCH better if you use the right kind.

There are more kinds, but these are the most common. en.wikipedia.org/wiki/List_of_

@tubetime Oh, are we doing "things everyone should know but no one ever tells you"?
Here's mine: there are two different kinds of "cross head" screws: Philips and Pozidrive. Pozidrive has the little diagonals, in the screws and in the drivers. The sizes are (of course), ever so slightly different, and the drivers will fit MUCH better if you use the right kind.

Tube❄️Time

@shezi don't forget JIS which is also quite common!

Johannes Spielmann

@tubetime I don't think we see those often in Europe.
Or I just never noticed and will have to live with the anguish caused by that. 😄

Token Sane Person

@tubetime Second fun fact. If you measure it like that you are short circuiting it. So only do this demo on a used cell.

Bob McWhirter

@tubetime @vmbrasseur all the vapers know this #18650.

Just like the potheads know 28 grams to the ounce.

Irenes (many)

@tubetime is it not... shorted through the calipers, when held like that?

well, you probably only did it for a moment

stojg

@tubetime I was just wondering about this a couple of days ago!

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