Why aren't AA batteries square?

No they weren't. Rolling what things up? Perhaps you're thinking of capacitors.

They (layer batteries) are perfectly good for the purpose intended, originally pocket transistor radios that draw very little current. Similarly HT batteries for valve radios.

Reply to
Max Demian
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"Legacy" is also why all cylindrical cells have a nipple at the top for the positive connection, originally a brass cap on the top of the carbon electrode, with the zinc case the negative. In alkaline cells the case is actually positive - steel - and there is a brass rod which is negative, but they have to have the same form factor as zinc/carbon cells for compatibility.

Reply to
Max Demian

James Wilkinson Sword posted for all of us...

Because your head is square. Commonly called a blockhead. Next...

Reply to
Tekkie®

It takes less material to create the same volume using circular cross section versus square cross section. Think of a rectangle formed by a piece of string, and observe that you can increase its area by deforming it (alternately, do the math).

Reply to
Bill

Please explain better about creating volume. It takes less material to get say, a 1" cross section. A cylinder will touch at 4 points in a rectangular opening battery pack. A 1" square bottle or can holds more volume than a 1" dia. cylinder. 1 x 1 = 1 sq, inch pi r2 (0.05 x

0.05) = 0.785 sq. inch. A square battery could have more power packed in the space than a round (cylinder) shaped one.
Reply to
Ed Pawlowski

First, when you are measuring the area of a cross-section, notice that you get inches^2, rather than inches. I use "in" below. If we have a string of length L forming a circle (of unknown radius r). Then L =

2*PI*r (circumference formula), so r = L/(2*PI), and consequently the area of the cross section is (from the area formula) A_1 = PI*r^2 = PI *(L/(2*PI))^2 = L^2/(4*PI) in^2.

The area of a rectangle having perimeter L is maximized when the rectangle is a square (that's a separate problem I won't go into now). However, in this case, where we have a square cross section, we we get side length s = L/4, so A_2 = (L/4)^2 = L^2/16 in^2.

We conclude that A_1/A_2 is about L^2/(4*PI) /(L^2/16)= 16/(4*PI) = 4/PI is about 1.27.

So A_1 is about 1.27 times the area of A_2.

Note that the result, does not depend on the value of L. Let me know if you have any questions or if you find an error (they happen!) : )

Bill

Reply to
Bill

WTF does your square have to do with volume?

So in conclusion:   A 1" square bottle or can hold more volume than a 1" dia.

Rectangular packaging is more efficient use of space than cylindrical.

Reply to
Ed Pawlowski

He's showing that you get maximum area with a given length bit of string if you arrange it in a circle rather than a square. This also means that if you battery is constant cross-section, as an AA is, the best shape for it to have to minimise the amount of case-material used to make it, is a cylinder.

Reply to
Tim Streater

That makes some sense. I don't know if batteries need a constant cross section but they may to have the best chemical reaction.

Reply to
Ed Pawlowski

Because batteries and cells are universally prisms - a area extended along a length, such as a cylinder. To refute, please link to a spherical battery.

Reply to
jgh

Well there was the one held by Inspecteur Clue-zo, which had "berm" written on the side. Or was that just a giant sparkler?

Reply to
Tim Streater

From the point of view of minimizing the use of materials for an enclosure, the *sphere* does best. And, I can't think of any reason why this wouldn't be a great design (ha!) ; )

Reply to
Bill
[snip]

Yes.

Spherical batteries would waste a lot of space between them. You'd need larger flashlights.

Reply to
Mark Lloyd

What do you mean, "them". You would only need one appropriately-sized battery (using more than one would be a waste of materials!) : )

Reply to
Bill

Why not say "torches"? they don't flash, most people turn them on, not on and off and on and off.

Reply to
James Wilkinson Sword

On Fri, 22 Sep 2017 20:22:18 +0100, Tekkie=AE wrote= :

re square in crosssection, they wouldn't roll off the desk.

At least I don't roll away. Place an AA on your desk, attempt to touch = the ends with a multimeter. Chase battery around the desk, pick it up o= ff the floor, then try again.

-- =

"Beam me aboard, Scotty!" [-] "Will a 2 X 4 do, Captain?"

Reply to
James Wilkinson Sword

What annoys me is rechargeable AAs. The casing is negative, covered by a very flimsy plastic sheath, which often gets damaged (they are kept for a decade instead of a year like with alkaline), hence you get positive and negative right next to each other at one end, which gets shorted, and all hell breaks loose since rechargeables have a very low internal resistance.

Reply to
James Wilkinson Sword

Try refilling a lemonade bottle. The bloody thing tips.

Reply to
James Wilkinson Sword

I thank you for your useful input to the discussion. Grow up.

Reply to
James Wilkinson Sword

Round is hard enough!

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Reply to
James Wilkinson Sword

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