Battery capacity - claimed versus real

Hi
Being rather a gear freak and particularly interested in the lights I acquired a charger that has a pretty good testing ability to determine actually capacity as it discharged the cell in test mode to get the actual capacity. Now capacity is dependent on discharge rate as a slow discharge rate means ultimately more energy can be extracted from a cell. To give you an idea an Alkaline can match it very closely with a Lithium providing that the discharge rate is reasonable and the temperature is within sensible ranges. By discharge rate, around 10 hours and greater would be a good guide and temperature say 15 to 35 degrees. Faster discharge rates and especially colder temperature then the Lithium pulls ahead by increasing amounts. So if you have a high lumen light that can kill a battery in under an hour then Alkalines are going to perform badly compared to Lithium chemistry. But if the device is say a GPS with ten plus hour drain rates then the extra that Lithium costs is not really worth it. But even then a GPS like my Garmin 62S complains bitterly about Alkaline batteries despite the low discharge rate. The much simpler Extrex is rather unfazed and happy with Alkaline batteries.
A NiMH is generally what I use so that is what I will be testing. It has proven to be very useful in explaining why some batteries work well and others do not. Also helps to sort your batteries by similar mAH as a weak cell can bring down it siblings very quickly in some devices. Also what I have noticed is reputable brands like Sanyo have been dropping the claimed capacity as they have been found out over stating capacity. Our Ebay Chinese friends can claim fantastic mAH capacity. Some is straight out lies while others might be supported by a test that draws very little current so get the absolute maximum out of a battery but with such low end voltage that practically it would have stopped working in most devices.
Anyway to start the ball rolling lets have a look at the highest claimed mAH for a AAA battery that I have. It is a NiMH cell chemistry and claims 1100 mAH. As you can see the claimed mAH is not supported by measured capacity but at least all the cells are consistent. The cells are in good condition and new apart from limited break in use.
Battery type Number Date Capacity mAH Pecentage of highest Pecentage of lowest Rank
Ansmann 1100 mAH 1 28/08/2011 911 100% 101% 1
Ansmann 1100 mAH 2 5/10/2011 902 99% 100% 3
Ansmann 1100 mAH 3 5/10/2011 907 100% 101% 2
Ansmann 1100 mAH 4 5/10/2011 901 99% 100% 4
Cheers
PS
And speaking of things that do not work lets start with how this website display tables. I even spaced then out by space characters and it still mucked up what I see on view but looks ok on edit
Being rather a gear freak and particularly interested in the lights I acquired a charger that has a pretty good testing ability to determine actually capacity as it discharged the cell in test mode to get the actual capacity. Now capacity is dependent on discharge rate as a slow discharge rate means ultimately more energy can be extracted from a cell. To give you an idea an Alkaline can match it very closely with a Lithium providing that the discharge rate is reasonable and the temperature is within sensible ranges. By discharge rate, around 10 hours and greater would be a good guide and temperature say 15 to 35 degrees. Faster discharge rates and especially colder temperature then the Lithium pulls ahead by increasing amounts. So if you have a high lumen light that can kill a battery in under an hour then Alkalines are going to perform badly compared to Lithium chemistry. But if the device is say a GPS with ten plus hour drain rates then the extra that Lithium costs is not really worth it. But even then a GPS like my Garmin 62S complains bitterly about Alkaline batteries despite the low discharge rate. The much simpler Extrex is rather unfazed and happy with Alkaline batteries.
A NiMH is generally what I use so that is what I will be testing. It has proven to be very useful in explaining why some batteries work well and others do not. Also helps to sort your batteries by similar mAH as a weak cell can bring down it siblings very quickly in some devices. Also what I have noticed is reputable brands like Sanyo have been dropping the claimed capacity as they have been found out over stating capacity. Our Ebay Chinese friends can claim fantastic mAH capacity. Some is straight out lies while others might be supported by a test that draws very little current so get the absolute maximum out of a battery but with such low end voltage that practically it would have stopped working in most devices.
Anyway to start the ball rolling lets have a look at the highest claimed mAH for a AAA battery that I have. It is a NiMH cell chemistry and claims 1100 mAH. As you can see the claimed mAH is not supported by measured capacity but at least all the cells are consistent. The cells are in good condition and new apart from limited break in use.
Battery type Number Date Capacity mAH Pecentage of highest Pecentage of lowest Rank
Ansmann 1100 mAH 1 28/08/2011 911 100% 101% 1
Ansmann 1100 mAH 2 5/10/2011 902 99% 100% 3
Ansmann 1100 mAH 3 5/10/2011 907 100% 101% 2
Ansmann 1100 mAH 4 5/10/2011 901 99% 100% 4
Cheers
PS
And speaking of things that do not work lets start with how this website display tables. I even spaced then out by space characters and it still mucked up what I see on view but looks ok on edit
