Kestrel
Flashaholic
An attempt to obtain statistical data regarding the average diameter of commonly-used rechargeable batteries.
After reading the following thread regarding the diameter of 18650's and fitting difficulties:
http://www.candlepowerforums.com/vb/showthread.php?t=221572
I did a little searching, the only thread (old & probably outdated, 2005, and it's a short one) that deals with battery diameters that I could find is this:
http://www.candlepowerforums.com/vb/showthread.php?t=93545
So if folks would like to measure the diameters of their relatively recently-manufactured commonly-used rechargeable cells (inches or mm) with a set of calipers and post them here, I will create a spreadsheet of their average and also their standard deviation if I can get a sufficient number of replies. In the interest of consistency, measuring the O.D. once over the label, and/or over the protection ?strip? that runs lengthwise down the body (for the protected cell types, right?), then averaging the two numbers, will probably result in the most useful measurement.
Once you know the standard deviation of a cell type, nearly the entire cell population should fall within three standard deviations of the mean. For an example:
Mean: 17.0 mm, STD: 0.1 mm
If you then purchase a cell of this type, it should have a ~68% chance of having an OD between 16.9 and 17.1 mm, a ~95% chance of an OD between 16.8 mm and 17.2 mm, and a ~99.7% chance of an OD between 16.7 and 17.3mm, assuming enough data has been collected (and assuming the data is normally distributed - which is a good assumption for a manufactured product). YMMV - your mileage may vary.
I've read a number of posts about people boring out their flashlight bodies and wondering what diameter they will need to shoot for. I am not sure what tolerances are needed for flashlight bodies for a tight or loose battery fit, someone else can worry about that if I can get together a statistically significant set of data on batteries.
I'd like to limit this to rechargeable LiIons, since I've seldom read about a fit issue with Lithium Primaries.
Please mention if each is protected or not, so I can make sure to differentiate between types.
I'll kick this off with my extensive <*cough*> collection:
AW 17500 (protected), 0.665" = 16.89 mm
AW 17500 (protected), 0.6655" = 16.90 mm
After reading the following thread regarding the diameter of 18650's and fitting difficulties:
http://www.candlepowerforums.com/vb/showthread.php?t=221572
I did a little searching, the only thread (old & probably outdated, 2005, and it's a short one) that deals with battery diameters that I could find is this:
http://www.candlepowerforums.com/vb/showthread.php?t=93545
So if folks would like to measure the diameters of their relatively recently-manufactured commonly-used rechargeable cells (inches or mm) with a set of calipers and post them here, I will create a spreadsheet of their average and also their standard deviation if I can get a sufficient number of replies. In the interest of consistency, measuring the O.D. once over the label, and/or over the protection ?strip? that runs lengthwise down the body (for the protected cell types, right?), then averaging the two numbers, will probably result in the most useful measurement.
Once you know the standard deviation of a cell type, nearly the entire cell population should fall within three standard deviations of the mean. For an example:
Mean: 17.0 mm, STD: 0.1 mm
If you then purchase a cell of this type, it should have a ~68% chance of having an OD between 16.9 and 17.1 mm, a ~95% chance of an OD between 16.8 mm and 17.2 mm, and a ~99.7% chance of an OD between 16.7 and 17.3mm, assuming enough data has been collected (and assuming the data is normally distributed - which is a good assumption for a manufactured product). YMMV - your mileage may vary.
I've read a number of posts about people boring out their flashlight bodies and wondering what diameter they will need to shoot for. I am not sure what tolerances are needed for flashlight bodies for a tight or loose battery fit, someone else can worry about that if I can get together a statistically significant set of data on batteries.
I'd like to limit this to rechargeable LiIons, since I've seldom read about a fit issue with Lithium Primaries.
Please mention if each is protected or not, so I can make sure to differentiate between types.
I'll kick this off with my extensive <*cough*> collection:
AW 17500 (protected), 0.665" = 16.89 mm
AW 17500 (protected), 0.6655" = 16.90 mm
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