DFiorentino
Flashlight Enthusiast
Just some testing of a variety of readily available IMR cells. I gathered two of each sample that I had for testing. Testing was done at 1C to determine the manufacturer's rating then again at calculated maximum rated discharge (see the summary chart for explanation). Some of the cell didn't live up to their max ratings so they were retested to determine their (subjective) practical maximum. You should be able to extrapolate any current in between my test discharge currents.
Summary:
Junsi iCharger 306B w/3.00V cut off + LogView 2.7.4.485 + data tables exported to Excel 2010. I have the full data table available, but figured capacity and voltage were the primary concerns. Note: on the updated graphs where the plot line does not reach the 3.00V x-axis, this is due to the voltage dropping faster than the software's datalog interval of 2 seconds. See the summary chart for the final values as taken off of the iCharger's display.
Out of four of these 18650 only one was able to perform near rated levels and able to withstand a 15C discharge. My three others performed similar to the blue, red and purple plots above.
These 26500 are pretty touchy near their somewhat low discharge limit. While @10A their voltage holding looks good and capacity is adequate, @ 12A+ they were unable to hold any voltage and capacity was @10% or worse.
It looks like I had one bad Shao red wrapped 18350.
...artificial cooling used to prevent iCharger cut off on over-temp (50°C)
And a popular LiCo for comparison…
And a not so common LiCo...
On deck: A123 systems 18650 and 26650 LiFePO4...
If I may generalize, there seems to be better power handling as you go longer vs. wider. I.E. 18650 handled higher current draw better than 26500; the same for 14500 vs. 16340. Additionally, if anyone thinks they will get these types of current draws in lights/devices with the batteries held by spring pressure alone is kidding themselves. I ran my tests multiple times with multiple test rigs and saw HUGE differences between testing with my modded 4Sevens battery cradle (with and without magnets on the cells for contact and 12awg wire connections) and my ratchet clamp setup (w/12awg wire connections).
-DF
EDIT: All charts up to date as of 11/2/11
Summary:
Junsi iCharger 306B w/3.00V cut off + LogView 2.7.4.485 + data tables exported to Excel 2010. I have the full data table available, but figured capacity and voltage were the primary concerns. Note: on the updated graphs where the plot line does not reach the 3.00V x-axis, this is due to the voltage dropping faster than the software's datalog interval of 2 seconds. See the summary chart for the final values as taken off of the iCharger's display.
Out of four of these 18650 only one was able to perform near rated levels and able to withstand a 15C discharge. My three others performed similar to the blue, red and purple plots above.
These 26500 are pretty touchy near their somewhat low discharge limit. While @10A their voltage holding looks good and capacity is adequate, @ 12A+ they were unable to hold any voltage and capacity was @10% or worse.
It looks like I had one bad Shao red wrapped 18350.
...artificial cooling used to prevent iCharger cut off on over-temp (50°C)
And a popular LiCo for comparison…
And a not so common LiCo...
On deck: A123 systems 18650 and 26650 LiFePO4...
If I may generalize, there seems to be better power handling as you go longer vs. wider. I.E. 18650 handled higher current draw better than 26500; the same for 14500 vs. 16340. Additionally, if anyone thinks they will get these types of current draws in lights/devices with the batteries held by spring pressure alone is kidding themselves. I ran my tests multiple times with multiple test rigs and saw HUGE differences between testing with my modded 4Sevens battery cradle (with and without magnets on the cells for contact and 12awg wire connections) and my ratchet clamp setup (w/12awg wire connections).
-DF
EDIT: All charts up to date as of 11/2/11
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