Adaptive charging method for lithium-ion battery cells

A charging method for charging and discharging a battery cell during recharge cycles, the method comprising the steps of

• monitoring the battery cell during a recharge cycle for determining an end of charge voltage (VEOC) during recharging of the battery cell and an end of discharge voltage (VEOD) during the discharging of the battery cell, the recharge cycle serving to charge the battery cell with capacity equal to a recharge fraction (RCF) amount of the amount of discharging capacity,
• determining an undercharge condition of the battery cell when the VEOD went below a low trigger level (VHigh) during the discharging and the VCOE stayed below a high trigger level (VHigh) during the recharging,
• increasing the RCF for a next cycle of the recharge cycle when in an undercharge condition,
• determining an undercharge condition of the battery cell when the VEOC went above VHigh during the recharging and the VCOD stayed above the VLow) during the discharging,
• decreasing the RCF for a next cycle of the recharge cycle when in an overcharge condition,
• determining a degraded condition of the battery cell when the VEOC went above VHigh during the recharging and VEOD went above VLow during the discharging,
• increasing the VHigh and decreasing VLow when in the degraded condition serving to increase a trigger range (DVT) being a difference between VHigh and VLow (DVT=VHigh−VLow),
• determining a normal condition of the battery cell when VEOC stayed below VHigh during recharging and VEOD stayed above VLow during discharging, and
• adjusting the RCF to center a voltage range being a difference between VEOC to VCOD within the trigger range.