BU-106: Advantages of Primary Batteries

Appreciate the importance of non-rechargeable (primary) batteries.

Primary batteries, also known as non-rechargeable batteries, tend to get overshadowed by the media attention secondary or rechargeable batteries receive. Heavy focus on one product over another may convince folks that primary batteries are old technology on the way out. Not so.

Primaries play an important role, especially when charging is impractical or impossible, such as in military combat, rescue missions and forest-fire services. Regulated under IEC 60086, primary batteries also service pacemakers in heart patients, tire pressure gauges in vehicles, smart meters, intelligent drill bits in mining, animal-tracking, remote light beacons, as well as wristwatches, remote controls, electric keys and children’s toys.

Most implantable pacemaker batteries are lithium-based, draw only 10–20 microamperes (µA) and last 5–10 years. Many hearing aid batteries are also primary with a capacity from 70–600mAh, good for 5–14 days before a replacement is needed. The rechargeable version offers less capacity per size and lasts for about 20 hours. Cost-saving is the major advantage.

High specific energy, long storage times and instant readiness give primary batteries a unique advantage over other power sources. They can be carried to remote locations and used instantly, even after long storage; they are also readily available and environmentally friendly when disposed.

The most popular primary battery is alkaline. It has a high specific energy and is cost effective, environmentally friendly and leak-proof even when fully discharged. Alkaline can
be stored for up to 10 years, has a good safety record and can be carried on an aircraft without being subject to UN Transport and other regulations. The negative is low load currents, limiting its use to light loads such as remote controls, flashlights and portable entertainment devices.

Moving into higher capacities and better loading leads to lithium-metal batteries. These have very strict air shipping guidelines and are subject to Dangerous Good Regulations involving Class 9 hazardous material. (See BU-704a: Shipping Lithium-based Batteries by Air.) Figure 1 compares the specific energy of lead acid, NiMH and Li-ion as secondary, as well as alkaline and lithium-metal as primary batteries.
 

Specific energy comparison of secondary and primary batteries Figure 1: Specific energy comparison of secondary and primary batteries.
Secondary batteries are typically rated at 1C; alkaline uses much lower discharge currents.
Courtesy of Cadex


Specific energy only indicates the capacity a battery can hold and does not include power delivery, a weakness with most primary batteries. Manufacturers of primary batteries publish specify specific energy; specific power is seldom published. While most secondary batteries are rated at a 1C discharge current, the capacity on consumer-grade primary batteries is measured with a very low current of 25mA. In addition, the batteries are allowed to discharge from the nominal 1.5V for alkaline to 0.8V before deemed fully discharged. This provides impressive readings on paper, but the results are less flattering when applying loads that draw higher currents.

Figure 2 compares the performance of primary and secondary batteries as “Rated” and “Actual.” Rated refers to the specific energy when discharging at a very low current; Actual discharges at 1C, the way most secondary batteries are rated. The figure clearly demonstrates that the primary alkaline performs well with light load typical to entertainment devices, while the secondary batteries represented by lead acid, NiMH and Li-ion have a lower rated capacity (Rated) but are better when being loaded with a 1C discharge (Actual).
 

Energy comparison under load Figure 2: Energy comparison underload. 
”Rated” refers to a mild discharge; “Actual” is a load at 1C. High internal resistance limits alkaline battery to light loads.
Courtesy of Cadex


One of the reasons for low performance under load conditions is the high internal resistance of primary batteries, which causes the voltage to collapse. Resistance determines how well electrical current flows through a material or device and is measured in ohms (Ω). As the battery depletes on discharge, the already elevated resistance increases further. Digital cameras with primary batteries are borderline cases — a power tool on alkaline would be impractical. A spent alkaline in a digital camera often leaves enough energy to run the kitchen clock for two years.

Table 3 illustrates the capacity of standard alkaline batteries with loads that run typical personal entertainment devices or small flashlights.
 

Alkaline specifications
Table 3: Alkaline specifications.
The discharge resembles entertainment devices with low loads.
Source: Panasonic
Note: Resistance can also be measured in siemens (s) units, which is equal to reciprocal ohm.
 

AA and AAA are the most common cell formats for primary batteries. Known as penlight batteries for pocket lights, the AA became available to the public in 1915 and was used as a spy tool during World War I; the American National Standards Institute standardized the format in 1947. The AAA was developed in 1954 to reduce the size of the Kodak and Polaroid cameras and shrink other portable devices. In the 1990s, an offshoot of the 9V battery produced the AAAA for laser pointers, LED penlights, computer styli and headphone amplifiers. (The 9V uses six AAAA in series.) Table 4 compares common primary batteries. (See BU-301: A look at Old and New Battery Packaging)
 

Summary of batteries available in AA and AAA format
Table 4: Summary of batteries available in AA and AAA format

The AA cell contains roughly twice the capacity of the smaller AAA at a similar price. This doubles the energy cost of the AAA over the AA. Energy cost often takes second stage in preference to downsizing. This is the case with bicycle lights where the AA format would only increase the size of the light slightly but could deliver twice the runtime for the same cost.

To cut cost, cities often consolidate purchases and this includes bulk acquisitions of alkaline batteries. A city the size of Vancouver, Canada, with about 600,000 citizens would buy roughly 33,000 AA, 16,000 AAA, 4,500 C and 5,600 D-size alkaline cells for general use.

Retail prices of the alkaline AA vary, so does performance. Exponent Inc. a US engineering firm, checked the capacity of eight brand-name alkaline batteries in AA packages and discovered an 800 percent discrepancy between the highest and lowest performers. The test standard was based on counting the shots of a digital camera until the batteries were depleted, a test that considered capacity and loading capability of a battery.

Figure 5 illustrates the number of shots a digital camera can take with discharge pulses of 1.3W using alkaline, NiMH and Lithium Li-FeS2 in an AA format. (With two cells in series at 3V, 1.3W draws 433mA.) The clear winner was Li-FeS2 (Lithium AA) with 690 pulses; the second was NiMH with 520 pulses, and the distant third was standard alkaline, producing only 85 pulses. Internal resistance rather than capacity governs the shot count. (See BU-801a: How to Rate Battery Runtime)
 

Pulse Number Figure 5: Number of shots a digital camera can take with alkaline NiMH and lithium.
Li-FeS2, NiMH and Alkaline have similar capacities; the internal resistance governs the shot count on a digital camera.  Li-FeS2, 3Ah, 690 pulses NiMH, 2.5Ah, 520 pulses Alkaline, 3Ah, 85 pulses. Test: ANSI C18.1
Source: Exponent


The relationship between battery capacity and current delivery is best illustrated with the Ragone Chart. Named after David V. Ragone, the Ragone chart evaluates an energy storage device on energy and power. Energy in Ah presents the available storage capacity of a battery that is responsible for the runtime; power in watts governs the load current.

Figure 6 illustrates the Ragone chart with the 1.3W load of a digital camera (indicated by the red arrow and dotted line) using lithium (Li-FeS2), NiMH and alkaline. The horizontal axis displays energy in Wh and the vertical axis provides power in watts. The scale is logarithmic to allow a wide selection of battery sizes.
 

Ragone Figure 6: Ragone chart illustrates battery performance with various load conditions.
Digital camera loads NiMH, Li-FeS2 and alkaline with 1.3W pulses according to ANSI C18.1 (dotted line). The results are:
- Li- FeS2 690 pluses
- NiMH 520 pulses
- Alkaline 85 pulses
Energy = Capacity x V
Power = Current x V
Source:  Quinn Horn, Exponent Inc.


The performance of the battery chemistries varies according to the position of the Ragone line. NiMH delivers the highest power and works well at high loads but it has the lowest specific energy. Lithium Li-FeS2 has the highest specific energy and satisfies moderate loading conditions, and alkaline offers an economic solution for lower current drains.


Summary

Primary batteries are practical for applications that draw occasional power, but they can get expensive when in continuous use. Price is a further issue when the packs are replaced after each mission, regardless of length of use. Discarding partially used batteries is common, especially in fleet applications and critical missions as it is convenient to simply issue fresh packs with each assignment rather than estimating the usage. At a battery conference a US Army general said that half of the batteries discarded still have 50 percent energy left.

The state-of-charge of primary batteries can be estimated by measuring the internal resistance. Each battery type needs its own look-up table as the resistive characteristics may differ. A more accurate method is coulomb counting that observes out-flowing energy, but this requires a more expensive circuit and is seldom done. (See BU-903: How to Measure State-of-charge – Coulomb Counting). This requires a more expensive circuit and is seldom done.


Reference

Presentation by Dan Durbin, Energizer Applications support, Medical Device & Manufacturing (MD&M) West, Anaheim, CA, 15 February 2012

Presentation by Quinn Horn, Ph.D., P.E. Exponent, Inc. Medical Device & Manufacturing (MD&M) West, Anaheim, CA, 15 February 2012

Last Updated 2016-06-02


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Comments

On April 6, 2011 at 8:20pm
Ramesh wrote:

supperb

On December 14, 2011 at 8:47am
Stephen J. Nichols wrote:

I beg to differ on alkaline batteries not leaking when. I have had a couple of flashlights that were used only a few times for brief periods and six months later would have to have the batteries almost driven out and yes they were turned off. Also televison remotes that worked a few minutes ago, and won’t now. When you go to change the batteries you have to clean the crud and corrosion out before installing the new batteries. From the looks of the amount of leakage and corrosion it had been going on for some time.
Do keep Battery University updated and on the web it does have a world of good information. An extremely handy reference.

On December 18, 2011 at 4:50pm
Mike wrote:

However Secondary cells are very poor to useless for long life low power consumption or device used intermittently with gaps of months (or even a few weeks for higher capacity NiMH) between use.  I recently had application for 80V at 5.5mA. The most economical and long use between replacements was 6 stacks of 26 x CR2032 Lithium coin cell parallel with 6 x 1N4148 diodes. About 6x capacity of Alkaline PP3 and recharging such a number of NiMH or Lithium ion in series is problematic as well as avoiding reverse charging a cell.

On February 14, 2012 at 7:57am
Nick wrote:

How I can measure the capacity of Zinc-carbon 6V battery ? I can discharge the batt by resistor f.e. 100ohm/1W. What are the formulas to calculate the capacity/Ah if I have cut off voltage f.e. 3.6V and know the discharging time in hours to achieve 3.6V.

On December 23, 2012 at 1:21am
Vipin wrote:

Can I use lithium and alkaline batteries together in one device?

On July 17, 2013 at 6:09pm
Kaz wrote:

The article is correct; alkaline batteries should not normally leak, whereas for zinc-carbon batteries, this is practically an expected behavior.

The reason why zinc-carbon batteries leak is that the casing of the battery serves as the negative terminal. The casing is consumed as the battery drains, and can perforate!

This is not true of alkaline batteries, whose casing is not one of the electrodes.

That is not to say that the casing cannot fail, but it’s not expected that mere discharge of the battery will “eat” through the casing.

On July 17, 2013 at 6:15pm
Kaz wrote:

You can use lithium and alkaline batteries in the same device, but not on the same circuit. They have different discharge rates.
 
The device has to have some separate circuits with separate power sources. This happens. For instance, a device that draws the bulk of its power from AAA batteries could have a coin battery on its circuit board (on a dedicated circuit) which maintains the contents of a non-volatile static RAM (NVRAM) chip. So that’s an example of one device with two kinds of batteries. A much more ancient example of multiple batteries are portable vacuum tube devices, which used three separate batteries: a battery for the vacuum tube heaters, another one (high voltage, 30 or more volts) for the plate, and a third battery for the grid bias!

If different types of batteries are connected in parallel, bad things will happen as one type of battery discharges to a lower voltage than the other (or is that way initially) and tries to charge the other.

In series, it is even worse, because a good battery in series with a dead one will reverse-bias the dead one (impose a reverse polarity on it).

Even new and old primary batteries OF THE SAME TYPE should not be put in series; you should change series battery packs at the same time.

 

On October 29, 2013 at 4:24pm
chloe wrote:

can you tell me information on a great value battery, a family dollar battery, duracell battery and a energizer battery. if you can that would be great !! im in the 7th grade and im doing a science project on battery life!!! if you can do this that would be great!!!

On December 14, 2014 at 9:42am
arsalan wrote:

I have fujitsu ah530 laptop i tried to replace the battery cell of my old battery with the same voltage and amphere cells but I failed the battery’s Positive terminal does not have any charge. I arranged another old dead battery from my friend but same results. in both senario the +ve terminal is not having any charge, when placed to laptop it does not
start on battery showing error “0% charge plugged in charging consider replacing your battery”. how to on solid state switch so that their would be a charge on +ve terminal and how can I resolve the issue please help me

On September 14, 2015 at 4:34am
Javier de Vicente wrote:

In possible manufacture 1,25 V primary batteries?

On January 25, 2016 at 6:48pm
Sharon wrote:

What results when an alkaline battery and a re- chargable battery are placed into a remote control (2 - AA batteries are required in the remote control)?

On February 4, 2016 at 5:06am
Kiki wrote:

Hi,
we have at work few power meters which we didn’ t use for almost a year. They have non-rechargeable Li batteries which were brand new but they are not working now. I heard that they can ‘sleep’ and there is some methods to wake them up. Can you give me some advice how to bring them back to system.
Thank you so much in advance!

Kiki

On March 11, 2016 at 7:41pm
Dmitri wrote:

Kiki,

The falling “asleep” is called passivation in primary lithium batteries. To “wake up” the batteries, put a low resistance high power load (say 90 ohm 5W resistor) load to draw some high current, and monitor the voltage - it will drop/start out slow, and within a minute it will raise to standard operating voltage.