Comparison of AA battery chemistries

[size=+3]Comparison of AA battery chemistries[/size]



In this article I will look at the 3 different AA battery chemistries: Alkaline, Lithium and NiMH. Alkaline and Lithium are primary batteries, i.e. not rechargeable, NiMH is rechargeable.
I am not including carbon-zinc batteries, they have worse performance than alkaline and are mostly obsolete.

The standard size of AA batteries is 50.5 mm long (including plus pole) and 14.5 mm in diameter, this was standardized in 1947 by IEC (but the battery was in use long before that).



[size=+2]Naming[/size]

The AA battery has been around a long time and during that time many different names has been used, both from manufacturers and from standard organizations.
IEC uses R6 for the AA battery size and then places a letter before, depending on chemistry, the most common are: LR6=Alkaline AA, FR6=Lithium AA, HR6=NiMH AA
ANSI uses 15A for alkaline AA, 15LF for lithium AA and 1.2H2 for NiMH AA.
Some of the other names used for the AA cell size is: penlight, mingon, MN1500, M



[size=+2]Voltage, capacity and other info[/size]


[size=+1]Alkaline[/size]



These batteries are rated 1.5 volt, their actual capacity is seldom specified, because it varies with load.
Energizer has a datasheet with specifications and their AA has about 2900mAh at 25mA load, but only about 1400mA at 500mA load.
According to Energizer the Alkaline battery will work down to -18°C, but with reduced capacity.
The shelf life can be up to 10 years.
The battery weights about 23 gram.

Alkaline batteries is also known to leak and destroy equipment, even unused cells can leak.



[size=+1]Lithium[/size]



These batteries are rated with 1.5 volt and has around 3000mAh.
According to Energizer the battery will work down to -40°C, but with reduced capacity.
The shelf life can be up to 15 years.
Unloaded voltage will be around 1.8 volt.
The battery weights about 15 gram.

The lithium batteries compared here is lithium-iron (Li-FeS2) batteries, there does also exist lithium batteries with 3 volt, they are usual sold in other sizes (CR123, CR2), but can also be found in AA size, but cannot be used instead of ordinary AA batteries.



[size=+1]NiMH[/size]



These batteries are rated with 1.2 volt, capacity is marked on the cell and is usual in the 2000mAh to 2700mAh range.

According to Sanyo the battery will work down to 0°C, but with reduced capacity.
The shelf life it not rated for rechargeable, but depending on type they can retain charge from a few weeks to a couple of years.

The battery weights 26 to 30 gram.



[size=+2]Comparison[/size]



First curve is at fairly low current. The alkaline battery lasts about 22 hours (2.2Ah at 0.1A), half the time is has higher voltage than the NiMH batteries, the rest of the time lower.
The lithium battery is the only battery that stays close to 1.5 volt and it is also the battery that delivers most energy.



Increasing the current to 1A is very hard on the alkaline battery, the voltage drops below the NiMH after a few minutes and continues down.
Again the lithium battery is the best, with highest voltage and most capacity, the capacity drop from 0.1A to 1A is small.





At 3A the alkaline battery cannot do much. NiMH works fine.
The lithium cell is also having problems, first the voltage drops, then it increase again while the cell heats.



The capacity shows how much current is in the batteries.



With energy it is the product of voltage and current that is summed, a buck or boost can use this energy, i.e. it can use extra voltage for more brightness or runtime.



This table is just the capacity converted to time.



[size=+2]Conclusion[/size]

The voltage printed on the cells, does not have much relation to actual voltage when using the cell. Alkaline marked with 1.5 volt has lower voltage than NiMH marked with 1.2 volt at higher loads (Like a flashlight on high). At very low loads alkaline will be better than NiMH.
Lithium has the highest voltage in most cases and can handle high loads.



[size=+2]Battery reviews[/size]

[size=+1]AA rechargeable[/size]
Eneloop AA HR-3UTGB 1900mAh (White)
Eneloop AA HR-3UWXB 2450mAh (Black)


[size=+1]AA primary[/size]
Panasonic Pro Power AA
Energizer Ultimate Lithium AA

Another great write up. Thank you for the information.

Excellent review. HKJ! You did compare the batteries very well and easily. Thanks a lot for your doing this great review. :thumbsup:
As an aside, I am surprised that NiMh battery will work down to 0°C, but with reduced capacity. Is it mainly due to the chemical components?

candle lamp said:

As an aside, I am surprised that NiMh battery will work down to 0°C, but with reduced capacity. Is it mainly due to the chemical components?

Click to expand...

Batteries uses chemical reactions, they slow down when the temperature drops and it looks like Sanyo has decided that 0°C is the practical low limit for their NiMH.
Even lithium slows down at lower temperature, they work at -40°C, but either you have to draw a very low current or you will only get a small part of the mAh.
At high temperature you can see the chemical reactions are working much better, look at the lithium at 3A load, how it improves when it get hot.

HKJ said:

Batteries uses chemical reactions, they slow down when the temperature drops and it looks like Sanyo has decided that 0°C is the practical low limit for their NiMH.
Even lithium slows down at lower temperature, they work at -40°C, but either you have to draw a very low current or you will only get a small part of the mAh.
At high temperature you can see the chemical reactions are working much better, look at the lithium at 3A load, how it improves when it get hot.

Click to expand...

Thanks for the reply. Are the Litium calls dangerous on their high temperature under load? What is most dangerous of three batteires on high temp.?

candle lamp said:

Thanks for the reply. Are the Litium calls dangerous on their high temperature under load? What is most dangerous of three batteires on high temp.?

Click to expand...

I would expect the lithium, but it does have safety devices, both a PTC that will reduce current at 85°C and a went that will blow at 150°C (This will disable the battery).
Alkaline batteries can also release gas, even at normal temperature, I have a few time had problems opening a flashlight due to that.

Another great article, thanks HKJ!

HKJ said:

The voltage printed on the cells, does not have much relation to actual voltage when using the cell. Alkaline marked with 1.5 volt has lower voltage than NiMH marked with 1.2 volt at higher loads (Like a flashlight on high). At very low loads alkaline will be better than NiMH.
Lithium has the highest voltage in most cases and can handle high loads.

Click to expand...

Hi HKJ,
I'm not sure if this question is appropriate.
Is there any side effects or potential issues with using NiMH on Fluke multimeters?
Fluke seems to be avoiding this question and keeps saying they recommend Alkaline.
Problem with Alkaline is that they leak.
May I ask whether you use Alkaline in your Fluke 289 and if so, are there any issues?
Thanks.

Planz said:

Hi HKJ,
I'm not sure if this question is appropriate.
Is there any side effects or potential issues with using NiMH on Fluke multimeters?
Fluke seems to be avoiding this question and keeps saying they recommend Alkaline.
Problem with Alkaline is that they leak.
May I ask whether you use Alkaline in your Fluke 289 and if so, are there any issues?
Thanks.

Click to expand...

I do use alkaline in my DMM's and luckily I have never seen a leak in them, but then I replace batteries fairly often.

I believe the main difference between using alkaline and NiMH in DMM's is the battery indicator. I know there is a couple of hours left when it turns on with alkaline, this is very important when I do a logging session, there is time enough to finish the logging, before the DMM turns off.

HKJ said:

I do use alkaline in my DMM's and luckily I have never seen a leak in them, but then I replace batteries fairly often.

I believe the main difference between using alkaline and NiMH in DMM's is the battery indicator. I know there is a couple of hours left when it turns on with alkaline, this is very important when I do a logging session, there is time enough to finish the logging, before the DMM turns off.

Click to expand...

Thanks. Other than 9V alkalines, I've pretty much given up on Alkalines as they have literally destroyed lots of my gear due to leakage.
So now, I'm putting NiMH into my Flukes if they are using AA or AAA.
I don't have data logging so if it's only the battery indicator or sudden cutoff, I can live with that.
I'll just swap or charge battery the minute the low battery indicator shows up.