Li-Ion battery charging, termination current (ITERM)

Question

How much does termination current (ITERM) affect the level of capacity in a Li-Ion battery?

I mean, in a given capacity (say battery 3.7V 1000mAh) how much charged would a battery be when the ITERM current is a) 20mA, b) 60mA, c) 180mA?

I known that the ITERM does matter when the charger is in the Costant Voltage phase and battery is being charged at its maximum regulation voltage, usually 4.2V. Therefore the charger stops its work when in CV phase the current drops below the ITERM value.

But I can't understand what difference would be in the total charge when this current was bigger or smaller. I do understand that the current level would be smaller in bigger values of ITERM but How can I calculate how much is this level?

Answer 1

I'm not an expert but the following article http://www.powerelectronics.com/mobile/proper-care-extends-li-ion-battery-life suggests:

Selecting a charger that uses minimum charge-current termination (C/10 or C/x) can also extend battery life by not charging to 100% capacity. For example, ending a charge cycle when the current drops to C/5 is similar to reducing the float voltage to 4.1 V. In both instances, the battery is only charged to approximately 85% of capacity, which is an important factor in battery life.

To take one of your examples, you have a 1000mAh battery, you charge 'til you reach 180mA, that's approx C/5, thus approx 85% of capacity. Elsewhere I read that C/10 results in ~92% of capacity. I don't have a formula, though, sorry.