Other Parts Discussed in Thread: BQ40Z50EVM-561
Dear TI Support Team,
I am using the charging board (BQ25700AEVM-732) to develop a Battery Test System with a lithium-ion battery (2.5 V to 4.2V, NMC) to cycle between charging, discharging, and rest states like a battery cycler would do. The battery, fuel gauge (BQ40Z50EVM-561), and charger are set up in a system with a power supply and a load. Discharging the battery works well, as the load applies a constant discharge current until the battery reaches the MinSystemVoltage() (Datasheet page 53). However, charging doesn’t work as intended as the charger starts reducing the current before the battery reaches MaxChargeVoltage() (Datasheet page 51).
This post mentions that it could be the resistance in the circuit and resulting I*R drop that causes the current to fall down. How can we guard against that?
One idea we had was to increase the MaxChargeVoltage reg setting to something higher than 4.2V, so that the charger would implement the CC upto 4.2V. Is there a way to determine what this voltage should be? And in this case, how could the charger be instructed to implement the CV step when the battery voltage reaches 4.2V?
The system diagram and system image can be seen below. Any guidance in this matter would be greatly appreciated.
