Replacing D-Cells with Four A-Cells - An Old Issue Revisited

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Dimensional packing problem:

Pack identically-sized smaller cylinders inside the smallest-possible larger cylinder.

That question may be reduced to -

Pack identically-sized smaller circles inside the smallest-possible larger circle



Ratio Solutions:

Two 1.000-diameter inner circles require 2.000-diameter outer circle

Three 1.000-diameter inner circles require 2.154-diameter outer circle

Four 1.000-diameter inner circles require 2.414-diameter outer circle

The four inner circle solution may be solved as 1 + Square Root of 2 = (1 + 1.414) = 2.414



AA Cell Diameter x Height Dimension range stated in millimeters (mm)

AA Cells may be from 13.5 to 14.5 mm diameter x 50.5 mm long

AA Rechargeable: 14.1 ± 0.6 mm. diameter



Representative In-Range Three AA-Cell Packing Solutions:

14.0 mm x 2.154 = 30.16 mm = 1.19 inch

14.5 mm x 2.154 = 31.23 mm = 1.23 inch

14.7 mm x 2.154 = 31.66 mm = 1.24 inch



Representative In-Range Four AA-Cell Packing Solutions:

14.0 mm x 2.414 = 33.80 mm = 1.33 inch

14.5 mm x 2.414 = 35.00 mm = 1.38 inch

14.7 mm x 2.414 = 35.49 mm = 1.40 inch



D-Cell Diameter x Height dimension range limits

D Cells may be from 33.1 to 34.2 mm diameter x 61.5 mm long

33.1 to 34.2 mm = 1.30 to 1.346 inch



Some earlier-reported AA-Cell diameter measurements:

Sanyo-GE ???? NiCd 0.546 (within 4-pack size limits)

Nexcell ??? mAh NiMH 0.548 (within 4-pack size limits)

Nomem 1500 mAh NiMH 0.550 (within 4-pack size limits)

Nomem 1800 mAh NiMH 0.554 (within 4-pack size limits)

Nomem 1600 mAh NiMH 0.554 (within 4-pack size limits)

Creative 1800 mAh NiMH 0.555 (within 4-pack size limits)

Nomem 2300 mAh NiMH 0.557 zero clearance, wont work

Powerex 2200 mAh NiMH 0.560 Too large



I have developed a solution by which AA-Cell size limits may be

tweaked to enable creating well-functioning D-Cell replacement

packs from four AA cells which would not appear possible from

the above analysis. I'll illustrate and describe it in my next post

to this thread. Clearly, some currently-available AA-Cells can

be used to form four-cell packs which can fit within space normally

allocated to accept all D-Cell diameters.



It would be helpful to generate a more contemporary list of popular

rechargeable AA cell diameters.



John
 
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