Batteries

[Cosmic Charlie]

I am just curious how all the different battery types got their numbering? For example, 18650's, or 14500's thanks.

 

[DellSuperman]

First 2 digits are the thickness diameter in mm..
18xxx = 18mm thick

Last 3 digits are the length in mm
Xx650= 650mm long

- JonK

 

[thedoc007]

Last 3 digits are the length in mm
Xx650= 650mm long

The length is specified by only the third and fourth digits. An 18650 is nominally 65 mm, not 650 (that would make it over 2 feet long). Not sure what the fifth digit signifies, but it is definitely NOT an indicator of the cell size.

As another example, an AAA is a 10440. 10 mm wide, 44 mm long. A 14500 is 14 mm wide, 50 mm long.

 

[Knight_Light]

First 2 digits are the thickness diameter in mm..
18xxx = 18mm thick

Last 3 digits are the length in mm
Xx650= 650mm long

- JonK

I am almost sure this is a typo but your claim of 650 mm long would be almost 25.6 inches.

 

[SilverFox]

The 0 at the end of the 18650 description means that it is a round cell.

Tom

 

[HKJ]

The 0 at the end of the 18650 description means that it is a round cell.

According to a book I have the last 3 digits is length in tenths (1/10) of mm and is based on a IEC standard, but I do not have the standard and cannot confirm it.

 

[DellSuperman]

Oh, sorry for the typo..
Thanks for correcting me. :o

- JonK

 

[thedoc007]

The 0 at the end of the 18650 description means that it is a round cell.

According to a book I have the last 3 digits is length in tenths (1/10) of mm and is based on a IEC standard, but I do not have the standard and cannot confirm it.

According to Wikipedia's "list of battery sizes" page, HKJ is correct.

"Commonly-used designation numbers indicate the physical dimensions of the cylindrical cell, in a way similar to the system used for lithium button primary cells. The larger rechargeable cells are typically assigned five-digit numbers, where the first two digits are the (approximate) diameter in millimeters, followed by the last three digits indicating the (approximate) height in tenths of millimeters."

To me that makes no sense, because even bare cells have a range of heights/widths. Specifying the cell to a tenth of a mm seems rather pointless when protection often adds several full millimeters, and for many applications, they still work fine.

The 0 indicating a round cell WOULD make much more sense to me, but apparently that isn't the case.

Interestingly, the same page also has a separate entry for 19670 cells, and the page states that 19670 is actually the correct designation for a protected cell, rather than 18650. Again, I don't really understand the distinction, since they vary from maybe 67 to 70 mm for protected cells. Seems like the standards are being ignored in any case, so claiming one or the other is correct when neither actually represents the real-world dimensions is silly.

Edit: I am going to continue to refer to them as protected 18650. More people understand that, and there is no possibility of confusing the numbers that way. As long as people like HKJ continue to give us real world measurements, and testing for that matter, I think we have the best of both worlds. Well understood designators, and a real-world measurement to ensure the correct fit for your use.

 

[Yamabushi]

To me that makes no sense, because even bare cells have a range of heights/widths. Specifying the cell to a tenth of a mm seems rather pointless when protection often adds several full millimeters, and for many applications, they still work fine.

The nomenclature system was probably created to encompass other types of cells which require 0.1 mm precision, e.g., a CR1216, CR1220 and CR1225 are 1.6, 2.0 and 2.7 mm thick respectively.

 

[SilverFox]

Hello HJK,

You are correct.

I am not sure what cells use 0 as referencing round cells, but I thought it was Li-Ion. The standards call for using R as indicating a Li-Ion round cell.

Tom