Li Ion Pulse Charging - Proof of Concept Test Part 7

Not much to report at present because a recent and unexpected diagnosis of Acute Myeloid Leukemia meant a plus 5 week hospital stay undergoing further testing and chemotherapy.

I did however download the log of test results before my stay for one of those chinese 18650 xxxxx mah cells. This was a new, but old stock, battery and had been used in a pulse charger to test the hardware and software. After 322 discharge cycles there did not appear to be any degradation in reported capacity. 

A few hours at home yesterday on day release meant I could download the logs for the abused tablet Li-Ion batteries. They too showed no signs of degradation after large number of cycles.

I don't know if that is the result of terminating the charge cycle at 3.95V, the discharge cycle at 2.96V or the pulse charging regime. When I get back on deck I will be able to finally start a proper trial to see if pulse charging is of a benefit.

Float Charging Li Ion Batteries - Results for New Cell after 12 months

Background and Method

More fully explained in this post but briefly I am using a control battery to confirm if any degradation is due to float charging or simply the passage of time and high ambient temperatures. Apart from the time being tested the test battery remains in a CC/CV charger floating at 3.93V. This charges the cell to approximately 70% of capacity then floats at this voltage. The control cell is charged to about 50% capacity before being removed from the charger and stored on the shelf. When the control battery is tested it is fully charged before the test.

Results after 12 Months

Having established a base line for the cell capacity when fully charged I have now floated one cell at 3.93V for 12 months. During the test period the floating cell has been subject to 22 discharge tests from the float voltage to 3.0V, and a further 5 discharge tests when fully charged.

Looking at the discharge tests of the battery left on float charge at 3.93V there was no meaningful degradation in capacity.

A full charge of the test battery versus the control battery shows no ill-effects after 12 months. While one cell is not a rigorous sample it should make the self-proclaimed experts feel very foolish. But since they confuse trickle charging with float charging, which are two different charging regimes, and never substantiate any of their claims I suspect they are pretty much clueless all of the time.

If you know how to float charge a Li-Ion cell then there is no evidence that a conservative float charge does any damage to the cell.

 

Testing Anko CR2032 cells in a Joule Smasher Led Flasher - Verdict Is Failed

After 178 days the Anko cell was finally exhausted. That fell well short of the 410 days expected suggesting the nominal capacity was much less than 210mAh. While I only tested one cell from the pack of 4 I wouldn't at present recommend theses cells. I'm going to try one of these Panasonic cells next which I have next. These appear to have lasted very well (I use it several times a day it seems) in my implementation of this continuity tester.