2nd cell shows the same numbers and as I am pretty shure all the other cells will do the same, I will not continue testing.
snakebite did the test @1A. IĀ“m sure my cells would just confirm his numbers.
It would be interesting to see some discharge diagrams in near future.
I got a few of the PKCell ICR18350, IMR18350 and ICR14500 batteries from AliExpress (fortunate to have ordered them last month, when they had free shipping via Turkey Post; just checked right now, and theyāre only offering expedited shipping options US$40+ Fedex ā seems like Turkey Post is not shipping batteries anymore).
What current should I charge them with? Standard charge current? Rapid charge current? There doesnāt seem to be a spec sheet. The sellerās page in AliExpress only indicates max continuous discharge current (2C for the ICR type, and 10C for the IMR type). How about discharge current (when testing discharge capacity), is 1C too high or still OK (for the ICR types).
based on the seller item page description:
PKCell ICR14500 750mAh max continuous discharge current = 2C = 1.5A, cut-off voltage = 3.00v
PKCell ICR18350 900mAh max continuous discharge current = 2C = 1.8A, cut-off voltage = 3.00v
PKCell IMR18350 700mAh max continuous discharge current = 10C = 7A, cut-off voltage = 2.75v
So far I did discharging of the above batteries at 0.25A discharge current and also getting around 800-900mAh (the ICR18350 900mAh and IMR18350 700mAh seem to have similar capacity?)
keep in mind my ir testing was impedance at 1khz.
thats the most common method in most datasheets.
and testing at 3.5v is testing a discharged cell.
ir goes up as cell is discharged.
quote.
Okay, i calculated the internal resistance of one of my PKcells, i think i did it right.
3.5 Volts is not discharged, 3.0 Volts is discharged.
But thanks for the point you make, i will test it again with a fully charged cell and one āhalf fullā at 3.7 Volts.
I didnāt know it depends on the charge.
I wouldnāt know why i should test at 1kHz, and iām not sure of you mean a PWM-ed load with 50% duty cycle at 1 kHz or what.
I was testing with a similar load as the turbo mode of a OTR M3 flashlight, which is a constant load of 2.3 Amperes.
3.5v open circuit is damn close to empty.
and at the steep rise in ir with the low state of charge.this is partly how fuel gauges in devices determine state of charge.
i am using a esr meter for capacitors but it does well for telling me state of health of pulls i am grading.i can test a group of the same cells from many packs in different states of wear from new to totally worn out and tell you which ones are new,useable,or a waste of time to charge.
its also great for spotting fakes once you record the results of a known real cell.
your dc ir test is sound but test again with a charged cell.
and dont expect this to match the ac test.esr meter=ac milliohmeter.