SilverFoxCPF
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Re:Battery testing questions... - 2007/09/03 18:27
Hello Guy,
In my last post we went step by step through a GP data sheet. I pointed out that the data sheets presented data in a very straight forward manner and were pretty easy to understand.
I am afraid that is not always the case...
I just ran across this data sheet.
http://www.batteryspace.com/prod-specs/AA_2600.pdf
There seems to be plenty of room for confusion on this one...
It appears that the chemical mix for these cells does not tolerate low discharge rates very well at all.
If we look at the minimum values on the sheet, this 2600 mAh cell comes in at 2170 mAh during a 2.6 amp discharge, but only 1085 mAh during a slower 1.3 amp discharge.
While this may seem to be counter intuitive, it could be that the chemistry used in this cell requires some heat to work properly. If that is the case, the heat from the higher discharge rate will allow the cell to give a higher capacity.
On the other hand, this could also be a typo...
I love the discharge graph. Discharging at 0.2C (whatever that is, but presumably 520 mA) after charging at 250 mA for 15 hours gives you 100% capacity.
I would say that this is an example of a very poorly written data sheet. If the data is accurate, this cell would have to be used in a specific application that draws in the 2 - 3 amp range to get the full capacity benefit of the cell.
This would be a great cell to study. If I send you some of them would you be interested in running them through your tests?
Tom
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