LR6 AA alkaline batteries - why is the capacity [mAh] [Ah] not or is given very rarely in the case of disposable (non-rechargeable) batteries?

As of 20.07.2021, there is no statutory obligation to provide the capacity of the mAh in the case of primary - disposable batteries.
Although legislative work is underway and the obligation to provide information about the performance of a given power source (including disposable batteries) will certainly appear, we still do not know in what shape it will be.

In the case of disposable batteries, however, this should not be simple information about the maximum capacity reached in mAh. Why not? - we will explain in this article.

The capacity measurement procedures for primary batteries, as well as for secondary cells (rechargeable batteries), are described in the relevant international IEC/PN-EN standards. Currently, however, there is no harmonisation provision that would standardise the method of measuring and stating the capacity of disposable batteries in such a way that they can be easily compared with each other.

The problem is the very large discrepancies in the obtained capacity results, depending on the target application. Batteries are tested according to different procedures as needed, obtaining different capacity results each time - even for the same batch of batteries. As our test of cells in the size of a 9V battery showed (The big test of 9V batteries, comparison of technologies: alkaline vs Ni-MH vs Li-ion, which is the best?), the same alkaline battery can reach a capacity that differs by more than 50%(!) depending on the adopted test procedure and discharge conditions - the final result is particularly influenced by the type of load (target application).

The official position of the European Committee for Electrotechnical Standardization CENELEC is that among the existing test procedures and standards, it is not possible to indicate a single, appropriate method for determining the nominal capacity of primary batteries. The huge number of variables affecting the life and performance of primary batteries (current consumption, battery age, temperature, method of use, etc.) makes marking the primary battery with a specific capacity would be very troublesome and could be misleading.

Technical Committee No. 35 of the International Electrotechnical Commission (IEC) has admitted that there is no single number (dom. capacity) that correctly describes the performance of a given primary (non-rechargeable) battery for the end user.

In accordance with the above, most manufacturers do not clearly provide the capacity values for primary (disposable) batteries. Capacity markings are usually not found directly on such batteries and their packaging.
The values given in some data sheets, etc., are only voluntary and illustrative.

The stated capacity will vary greatly depending on the test procedure used, so there is no comparative value and no real information about the performance of a given battery for the end user in a particular application.

Let's take an example, hypothetical two LR6 AA alkaline batteries. A cheaper battery described as 2700 mAh and a high-end battery (3 times more expensive) described as 2100 mAh. Does this mean that a cheaper battery is clearly better because it has a higher capacity?

First of all, when the manufacturer provides capacitance values, let's determine what their nature is and what load conditions they have been measured. Are these conditions the same for both compared batteries? A fairly common rule of thumb is that an alkaline battery from the high segment will achieve a much better capacity result in an energy-demanding device, while paradoxically, when used in a very simple, undemanding device, it can last less than a clearly cheaper battery. Comparing one capacity value between two disposable batteries does not make sense - even if a given battery has a higher capacity under the same conditions, we are still not really sure how it will work in practice.

In conclusion, one capacity value does not carry enough information to determine whether a given disposable battery will be better than another.
This applies to virtually any disposable battery, including hearing aid batteries (zinc-air), alkaline LR6 AA, LR03 AAA, also button batteries type AG13 LR1154, CR2032 lithium batteries, etc.

The situation is different in the case of secondary cells (rechargeable batteries), which show much greater stability regardless of the adopted test procedure or method of use. In the case of rechargeable batteries, the requirement to provide capacity expressed in milliampere-hours [mAh] or ampere-hours [Ah] is an obligation according to Commission Regulation (EU) No. 1103/2010 of 29 November 2010 establishing, pursuant to Directive 2006/66/EC of the European Parliament and of the Council, rules on the labelling of secondary (rechargeable) and automotive batteries and accumulators with information on their capacity. Remember, however, that even if we compare the capacity between batteries, we can only do so if their rated voltage is identical - a 12V 50 Ah car battery stores three times more energy than a 50 Ah Power Bank with a 3.7V battery - despite the same capacity expressed in Ah.

Author: Michał Seredziński
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