BU-301: A look at Old and New Battery Packaging

Discover familiar battery formats, some of which going back to the late 1800s.

Early batteries of the 1700s and 1800s developed in Europe were mostly encased in glass jars. As batteries grew in size, jars shifted to sealed wooden containers and composite materials. In the 1890s, battery manufacturing spread from Europe to the United States and in 1896 the National Carbon Company successfully produced a standard cell for widespread consumer use. It was the zinc-carbon Columbia Dry Cell Battery producing 1.5 volts and measuring 6 inches in length.

With the move to portability, sealed cylindrical cells emerged that led to standards sizes. The International Electrochemical Commission (IEC), a non-governmental standards organization founded in 1906, developed standards for most rechargeable batteries. In around 1917, the National Institute of Standards and Technology formalized the alphabet nomenclature that is still used today. Table 1 summarizes these historic and current battery sizes.





F cell

33 x 91 mm

Introduced in 1896 for lanterns; later used for radios; only available in nickel-cadmium today.

E cell


Introduced ca. 1905 to power box lanterns and hobby applications. Discontinued ca. 1980.

D cell

34.2 x 61.5mm

Introduced in 1898 for flashlights and radios; still current.

C cell
25.5 x 50mm Introduced ca. 1900 to attain smaller form factor.


22.2 x 42.9mm

Cordless tool battery. Other sizes are ½, 4/5 and 5/4 sub-C lengths. Mostly NiCd.

B cell

20.1 x 56.8mm

Introduced in 1900 for portable lighting, including bicycle lights in Europe; discontinued in in North America in 2001.

A cell

17 x 50mm

Only available as a NiCd or NiMH cell; also available in 2/3 and 4/5 size. Popular in old laptops and hobby batteries.

AA cell

14.5 x 50mm

Introduced in 1907 as penlight battery for pocket lights and spy tool in WWI; added to ANSI standard in 1947.

AAA cell

10.5 x 44.5mm

Developed in 1954 to reduce size for Kodak and Polaroid cameras. Added to ANSI standard in 1959.

AAAA cell

8.3 x 42.5mm

Offshoot of 9V, since 1990s; used for laser pointers, LED penlights, computer styli, headphone amplifiers.

4.5V battery

67 x 62
x 22mm

Three cells form a flat pack; short terminal strip is positive, long strip is negative; common in Europe, Russia.

9V battery

48.5 x 26.5
x 17.5mm

Introduced in 1956 for transistor radios; contains six prismatic or AAAA cells. Added to ANSI standard in 1959.


18 x 65mm

Developed in the mid-1990s for lithium-ion; commonly used in laptops, e-bikes, including Tesla EV cars.


26 x 65mm

Larger Li-ion. Some measure 26x70mm sold as 26700. Common chemistry is LiFeO4 for UPS, hobby, automotive.


14x 50mm

Li-ion, similar size to AA. (Observe voltage incompatibility: NiCd/NiMH = 1.2V, alkaline = 1.5V, Li-ion = 3.6V)

21700* 21 x 70mm

New (2016), used for the Tesla Model 3 and other applications, made by Panasonic, Samsung, Molicel, etc.

32650 32 x 65mm Primarily in LiFePO4 (Lithium Iron Phosphate)

Table 1: Common old and new battery norms.
*  The 21700 cell is also known as 2170. IEC norm calls for the second zero at the end to denote cylindrical format.

Standardization included primary cells, mostly in zinc-carbon; alkaline emerged only in the early 1960s. With the growing popularity of the sealed nickel-cadmium in the 1950s and 1960s, new sizes appeared, many of which were derived from the “A” and “C” sizes. Beginning in the 1990s, makers of Li-ion departed from conventional sizes and invented their own standards.

A successful standard is the 18650 cylindrical cell. Developed in the early 1990s for lithium-ion, these cells are used in laptops, electric bicycles and even electric vehicles (Tesla). The first two digits of 18650 designate the diameter in millimeters; the next three digits are the length in tenths of millimeters. The 18650 cell is 18mm in diameter and 65.0mm in length.

Other sizes are identified with a similar numbering scheme. For example, a prismatic cell carries the number 564656P. It is 5.6mm thick, 46mm wide and 56mm long. P stands for prismatic. Because of the large variety of chemistries and their diversity within, battery cells do not show the chemistry.

Few popular new standards have immerged since the 18650 appeared in ca. 1991. Several battery manufacturers started experimenting using slightly larger diameters with sizes of 20x70mm, 21x70mm and 22x70mm. Panasonic and Tesla decided on the 21x70, so has Samsung, and other manufacturers followed.  The “2170” is only slightly larger than the 18650 it but has 35% more energy (by volume). This new cell is used in the Tesla Model 3 while Samsung is looking at new applications in laptops, power tools, e-bikes and more. It is said that the best diameters in terms of manufacturability is between 18mm and 26mm and the 2170 sits in between. (The 2170 is also known as the 21700.) The 26650 introduced earlier never became a best-seller.

The 32650 is primarily available in LiFePO4 (Lithium Iron Phosphate) with a nominal voltage of 3.2V/cell and a typical capacity of 5,000mAh. The dimensions are 32x65mm; true sizes may be slightly larger to allow for insulation and labels.

On the prismatic and pouch cell front, new cells are being developed for the electric vehicle (EV) and energy storage systems (ESS). Some of these formats may one day also become readily available similar to the 18650, made in high energy and high power versions, sourced by several manufacturers and sold at a competitive prices. Prismatic and pouch cells currently carry a higher price tag per Wh than the 18650.

The EV and ESS markets advance with two distinct philosophies: The use of a large number of small cells produced by an automated process as low cost, as done by Tesla, versus larger cells in the prismatic and pouch formats at a higher price per Wh for now, as done by other EV manufacturers. We have not seen clear winners of either format; time will tell.

Looking at the batteries in mobile phones and laptops, one sees a departure from established standards. This is due in part to the manufacturers’ inability to agree on a standard, meaning that most consumer devices come with custom-made cells or battery packs. Compact design and market demand are swaying manufacturers to go their own way. High volume with planned obsolescence allows the production of unique sizes in consumer products. 

In the early days, a battery was perceived “big” by nature, and this is reflected in the sizing convention. While the “F” nomenclature may have been seen as mid-sized in the late 1800s, our forefathers did not anticipate that a battery resembling a credit card could power computers, phones and cameras. Running out of letters towards the smaller sizes led to the awkward numbering of AA, AAA and AAAA.

Since the introduction of the 9V battery in 1956, no new formats have emerged. Meanwhile portable devices lowered the operating voltages to between 3V and 5V. Switching six cells (6S) in series to attain 9V is expensive to manufacture, and a 3.6V alternative would serve better. This imaginary new pack would have a coding system to prevent charging primaries and select the correct charge algorithm for secondary chemistries.

Starter batteries for vehicles also follow battery norms that are based on the North American BCI, the European DIN and the Japanese JIS standards. These batteries are similar in footprint to allow swapping. Deep-cycle and stationary batteries follow no standardized norms and the replacement packs must be sourced from the original maker. The attempt to standardize electric vehicle batteries may not work and might follow the failed attempt to standardize laptop batteries in the 1990s.

Future Cell Formats

Standardization for Li-ion cell formats is diverse, especially for the electric vehicle. Research teams, including Fraunhofer,* examine and evaluate various formats and the most promising cell types until 2025 will be the pouch and the 21700 cylindrical formats. Looking further, experts predict the large-size prismatic Li-ion cell to domineer in the EV battery market. Meanwhile, Samsung and others bet on the prismatic cell, LG gravitates towards the pouch format and Panasonic is most comfortable with the 18650 and 21700 cylindrical cells.

Large battery systems for ESS, UPS, marine vessels and traction use mostly large format pouch cells stacked with light pressure to prolong longevity and prevent delamination. Thermal management is often done by plates drawing the heat between layers to the outside and liquid cooling.
*  Fraunhofer is Europe's largest research organization focusing on health, security, communication, energy and the environment.

Last updated 2018-05-17

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Comments (16)

On March 1, 2011 at 2:37am
Atul Gupta wrote:

i have seen some Li-ion pouch cells packaging with terminals on top. can we mount the same cell in 90 Deg rotation condition i.e. terminals are in side instead of top?

On August 18, 2011 at 11:00am
Steven wrote:

The B cell battery is 20.1 millimeters in diameter and 56.8 millimeters in length. It is still in use in Europe.

On February 17, 2012 at 3:58pm
BWMichael wrote:

Atul Gupta: Of course. You could easily modify the battery yourself to have the contacts on the side. Or just turn the battery 90 degrees? I see mobile phone batteries all the time which go in the phone sideways, the contacts being on the side of the phone.

On December 21, 2012 at 9:42pm
Matty deBarri wrote:

Slight correction to table 1:  26700 slightly longer than 26650 (5mm).  Diameters identical.

On October 25, 2013 at 11:20am
Eric Q wrote:

There are also two even larger sizes of Li-Ion batteries which are used in flashlights, among other things.  They are, the 32600(32mm X 60mm) which is about the size of “D” cell; and the 32650(32mm X 65mm), just slightly longer, the largest cylindrical size that I am aware of.  It’s a continuation of the 18650 and 26650 format, which allows an even higher capacity.  There are also similar numbered sizes, such as 14500, and 10440, which are equivalent to the “AA” and “AAA”, respectively; and many, many other variations.

On November 23, 2013 at 7:17pm
Heiko wrote:

I didn’t know the 18650 were used in almost all laptop batteries and even electric vehicles.

But they are also typical batteries for modern led flashlights, I learned about them looking for a professional head-mounted flashlight - I finally got a Spark headlight and two 3400mAh protected 18650s with Panasonic cells. Perfect combination, that thing is an intense flood light and the batteries last for hours on full power smile

On December 13, 2013 at 8:52am
ian wrote:

There used to be a flashlight size called Double-D.  It was twice the length of a d-cell and put out 3v.  It was popular in the maglite style flashlights of the 60’s and 70’s.  Could use them anywhere you had a 2-d stack.

On August 3, 2014 at 7:48pm
Edward wrote:

i am a battery engineer in a battery company, any battery questions please email to me zzrm316@163.com Edward

On October 16, 2015 at 9:48am
Kevin wrote:

Hello there, love the info on this site, learnt alot.
Can you help with a question Im sure would seem very simple to you. I have 2 batteries (AA, tagged, rechargeable) both the same power (1400), one, however is size AA 4/5 the other normal AA size, are they interchangeable? Is it only the physical dimensions which are different?
Kind regards

On November 7, 2015 at 3:20am
carbatterymp wrote:

im battery seller and i find that this site is extremely informative for me

On December 14, 2015 at 8:28pm
Marvin Milewits wrote:

The title of this article is misleading.  It should be “A look at Old and New Cell Packaging’.  Battery implies many cells unless a 1 cell battery is explicitly stated.

On December 25, 2016 at 2:04am
Joe Gutierrez wrote:

Hello I am a investor and I like the price on lithium corps like cbak ,just wanted to know what you thought on the batteries

On August 27, 2017 at 12:39am
Rudi wrote:

The trend to smaller devices calls for smaller batteries too, so smaller sizes emerge.
They start -and likely stay- for a niche market, but may also become a standard. Examples are 26350, 18350, 16340 and 10180.
The 16340 can be called a real standard and is better known as CR123.

On September 7, 2017 at 11:33am
phil buckley wrote:

I recently rewrapped an Efest 18650 li battery, and with the old wrap off, I found a greek symbol “Beta” stamped in the edge of the bottom. Does anybody know what this means??

On October 24, 2017 at 4:37am

I am an academican in siirt university,turkey who want to study about battery. I want to know what importance is in battery development in area batteries?The most hindrance?İf anyone need to me my email is above, my best wishes…

On January 19, 2019 at 9:30am
Wilmar Alves Cruvinel de Lima wrote:

I remember that on fiveties abd sixties existed a radio battery that was aproximattely two ft long fit on an iron can.  Anyone know this model?