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

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

Early batteries of the s and s 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 s, battery manufacturing spread from Europe to the United States and in 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.

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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 , developed standards for most rechargeable batteries. In around , 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.

Size

Dimensions

History

F cell

33 x 91 mm

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

E cell

N/A

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

D cell

34.2 x 61.5mm

Introduced in for flashlights and radios; still current.C cell

25.5 x 50mm

Introduced ca. to attain smaller form factor.

Sub-C

22.2 x 42.9mm
16.1mL

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

A cell

17 x 50mm

Available in NiCd, NiMH and primary lithium; also in 2/3 and 4/5 sizes. Popular in older laptops and hobby applications.

AA cell

14.5 x 50mm

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

AAA cell

10.5 x 44.5mm

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

AAAA cell

8.3 x 42.5mm

Offshoot of 9V, since s; 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

You will get efficient and thoughtful service from xiaolu.

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18 x 65mm
16.5mL

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

26 x 65mm
34.5mL

Larger Li-ion. Some measure 26x70mm sold as . 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)*21 x 70mmNew (), used for the Tesla Model 3 and other applications, made by Panasonic, Samsung, Molicel, etc.32 x 65mmPrimarily in LiFePO4 (Lithium Iron Phosphate)Table 1: Common old and new battery norms.

* The cell is also known as . 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 s. With the growing popularity of the sealed nickel-cadmium in the s and s, new sizes appeared, many of which were derived from the &#;A&#; and &#;C&#; sizes. Beginning in the s, makers of Li-ion departed from conventional sizes and invented their own standards.

A successful standard is the cylindrical cell. Developed in the early s for lithium-ion, these cells are used in laptops, electric bicycles and even electric vehicles (Tesla). The first two digits of designate the diameter in millimeters; the next three digits are the length in tenths of millimeters. The 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 P. 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 appeared in ca. . 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 &#;&#; is only slightly larger than the 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 sits in between. (The is also known as the .) The introduced earlier never became a best-seller.

The 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 , 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 .

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 s, 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 , 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 s.

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 will be the pouch and the 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 and 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.

Safety Concerns with Rechargeable Cells

Off-the-shelf cells have primarily been non-rechargeable and for public use. Typical applications are spares for flashlights, portable entertainment devices and remote controls. Accidental shorting with keys or coins in a jean pocket only causes an alkaline cell to heat up and not catch fire. The voltage collapses on an electrical short because of high internal resistance; removing the short stops the reaction. (See BU-304c: Battery Safety in Public)

Rechargeable cells are normally encapsulated in a for-purpose pack. The exception is the available as a spare cell for vaping. Looking like a large AA cell, these Li-ion cells can inflict acute injury, even death, if mishandled. If shorted, an unprotected Li-ion cell will vent with flame. Once the jet-like explosion is in progress, removing the short no longer stops the reaction and the cell burns out. Li-ion&#;s ability to deliver high power is a characteristic that must be respected. (See also BU-304c: Battery Safety in Public)

The cell can be made safe with built-in safety circuits described in BU-304b: Making Lithium-ion Safe. With protection, excessive current shuts the cell down, either momentarily by a heat element or permanently by an electric fuse. But the fused has the disadvantage of shutting down when high current is needed on purpose, such as vaping. Spare cells for vaping are normally unprotected.

Another cause of fire is low quality no-brand cells. Li-ion batteries are safe if made by a reputable manufacturer. Many aftermarket cells do not have the same rigorous safety checks as brand name products have. (See BU-810: What Everyone Should Know About Aftermarket Batteries) Cells can also be damaged by stress related to heat, shock, vibration and incorrect charging or loading.

Underwriters Laboratory (UL) may change the safety regulations by mandating that commercially available cells, like the , cannot be removed by the customer.

* Fraunhofer is Europe's largest research organization focusing on health, security, communication, energy and the environment.

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