Power Me Up
Enlightened
This is a followup to my testing of the Accupower Evolution C size Low Self Discharge Cells here:
http://www.candlepowerforums.com/vb/showthread.php?t=187271
I've completed testing on a total of 6 of these D cells purchased from Thomas Distributing:
http://thomasdistributing.com/shop/...batteriesbrprecharged-2-battery-pk-p-997.html
All discharge tests were done on my 0FAB02 firmware Maha C9000 charger/analyzer.
Out of the packet, the cells gave an average of:
8079mAh
(Min 7678, Max 8239, St Dev 206)
Charged on the C808M, they gave an average of:
9886mAh
(Min 9778, Max 9959, St Dev 64)
After charging on the C808M and topped off with the C9000, they gave an average of:
10497mAh
(Min 10290, Max 10710, St Dev 168)
Although not as impressive as the performance given by their C sized equivalents, they still seem to be very good cells, giving almost 5% over their rated capacity when topped off with the C9000. Unlike the C sized cells, they actually came in under their rated capacity when only charged on the C808M, but only by an average of less than 1.2%
Again, there were no markings on the cells to indicate when they were manufactured (and it's impossible to know how fully charged they were when new) so it's not possible at this stage to evaluate their self discharge rate, but at about 80% of rated capacity out of the package, they can still claim that they're pre-charged and ready to use!
Edit: I've created a new thread with a photo of how I've attached the C & D cells in the C9000:
http://www.candlepowerforums.com/vb/showthread.php?t=213363
Update (22nd of September 2012)
I've just finished running another batch of tests on these cells. These cells have been sitting idle since November 2008 - nearly 4 years!
Initial discharge capacities as measured on my iCharger 206B were:
4725
5336
4264
266
2882
4271
Obviously cells 4 & 5 didn't fare so well, but the rest weren't too bad considering the length of time that they've been sitting idle for. Even the better cells aren't up to the same standard that we expect from Eneloops however. Looking back over the historical data, cell 4 has always performed poorly with self discharge - even out of the packet. Cell 5 initially looked OK, but also showed higher self discharge on the 6 month test.
After running a few cycles on them, I performed a final test by initially charging them in my Maha C808M followed by a top off on the 206B and a discharge at 2.5A on the 206B:
9970
9689
9700
9684
10049
10019
Average capacity was 98.5% of their rated capacity, so not too shabby for cells that are now at least 4.5 years old.
Discharge curves:
A larger version of the above chart can be viewed here:
http://www.bogswamp.com/AccuPower D Discharge Chart.png
Even considering the weaker cells, this isn't too bad - the weaker cells would probably still have quite useful capacity at 12 months since the last charge.
Even if I was to totally disregard the poor results from cells 4 & 5, I couldn't recommend that others purchase these cells anymore due to reports that the latest versions aren't performing anywhere near as well as these original versions:
http://www.candlepowerforums.com/vb/showthread.php?309280-AccuEvolution-D-Cells-quality-gone!
http://www.candlepowerforums.com/vb/showthread.php?t=187271
I've completed testing on a total of 6 of these D cells purchased from Thomas Distributing:
http://thomasdistributing.com/shop/...batteriesbrprecharged-2-battery-pk-p-997.html
All discharge tests were done on my 0FAB02 firmware Maha C9000 charger/analyzer.
Out of the packet, the cells gave an average of:
8079mAh
(Min 7678, Max 8239, St Dev 206)
Charged on the C808M, they gave an average of:
9886mAh
(Min 9778, Max 9959, St Dev 64)
After charging on the C808M and topped off with the C9000, they gave an average of:
10497mAh
(Min 10290, Max 10710, St Dev 168)
Although not as impressive as the performance given by their C sized equivalents, they still seem to be very good cells, giving almost 5% over their rated capacity when topped off with the C9000. Unlike the C sized cells, they actually came in under their rated capacity when only charged on the C808M, but only by an average of less than 1.2%
Again, there were no markings on the cells to indicate when they were manufactured (and it's impossible to know how fully charged they were when new) so it's not possible at this stage to evaluate their self discharge rate, but at about 80% of rated capacity out of the package, they can still claim that they're pre-charged and ready to use!
Edit: I've created a new thread with a photo of how I've attached the C & D cells in the C9000:
http://www.candlepowerforums.com/vb/showthread.php?t=213363
Update (22nd of September 2012)
I've just finished running another batch of tests on these cells. These cells have been sitting idle since November 2008 - nearly 4 years!
Initial discharge capacities as measured on my iCharger 206B were:
4725
5336
4264
266
2882
4271
Obviously cells 4 & 5 didn't fare so well, but the rest weren't too bad considering the length of time that they've been sitting idle for. Even the better cells aren't up to the same standard that we expect from Eneloops however. Looking back over the historical data, cell 4 has always performed poorly with self discharge - even out of the packet. Cell 5 initially looked OK, but also showed higher self discharge on the 6 month test.
After running a few cycles on them, I performed a final test by initially charging them in my Maha C808M followed by a top off on the 206B and a discharge at 2.5A on the 206B:
9970
9689
9700
9684
10049
10019
Average capacity was 98.5% of their rated capacity, so not too shabby for cells that are now at least 4.5 years old.
Discharge curves:
A larger version of the above chart can be viewed here:
http://www.bogswamp.com/AccuPower D Discharge Chart.png
Even considering the weaker cells, this isn't too bad - the weaker cells would probably still have quite useful capacity at 12 months since the last charge.
Even if I was to totally disregard the poor results from cells 4 & 5, I couldn't recommend that others purchase these cells anymore due to reports that the latest versions aren't performing anywhere near as well as these original versions:
http://www.candlepowerforums.com/vb/showthread.php?309280-AccuEvolution-D-Cells-quality-gone!
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