Li Ion Pulse Charging - Proof of Concept Test Part 5

 I wasn't going to bore you further with the results of the "test" runs but today I noticed something. One of the outcomes from testing cells which are now abused is that the low cell capacity gives a fast cycle turn around. I was looking at cell F, which has now been though 300+ pulse charge cycles, and I was trying to understand the cyclical variation in capacity.

It appears that the reported cell capacity for a charge/discharge cycle is highly correlated (r=0.974) with the cell voltage at the first discharge measurement. This measurement is taken 20 seconds after discharge commences. 

 The first handful of observations demonstrate this:

	Cycle	mAh	Voltage at t=20 sec
	1	77.3	3.779
	2	69.7	3.773
	3	68.3	3.766
	4	67.2	3.760
	5	65.8	3.753
	6	63.6	3.747
	7	63.4	3.747
	8	62.2	3.740
	9	62.1	3.740
	10	62.2	3.740
	11	62.3	3.740
	12	68.1	3.760
	13	74.1	3.779

Comparing cycle 11 and 12 a 20mV difference in the cell voltage existed after 20 secs of the discharge test. The ADC step size is 6.5mV per bit. So it's a much larger error than I expected and some experimentation with the charge termination is required.