BlueSwordM
(BlueSwordM)
19
Just set it to 4,20V.
The voltage level doesn’t really matter when it has completed the CV phase.
The reason the voltage drops, as you probably already know, is that the cell’s internal resistance comes into play once it’s not subjected to a potential difference.
Therefore, even fully charged, the cell voltage will drop it a little. As long as it doesn’t go below 4,17V when you instantly remove it from the charger, and you are good.
For lithium-ion cells, and NiMH cells, internal resistance goes down as the voltage goes down. So it’s not actually bad, since under heavy load, instead of dropping 4,20V to 4,09V, the cell drops from 4,15V-4,09V.
It is a strange phenomenon indeed, but a good one.