bq25703A: Setting voltage termination Level

Part Number:bq25703A

Hello, I am Currently temporarily taking over a project for a colleague.

The work I am doing is a complete profile of our battery pack. 2300mAh, 5 cell, 6V nominal.

While charging the batteries using the MSP430 contoller and Bqstudio I notice that there was no charging termination or current change during the charging process. The Battery would keep charging at 1 Amp forever and would not stop once the peak voltage was reached. I am familiar with how other systems detect when the battery is fully charged and stop the charge process.(eg. Delta T, Delta V and termination voltage). In the bqStudio I can see the voltage on the battery reaching peak and then declining, yet the charge is not being stopped. Am I right to think that during the profiling process the host (MSP) is talking to the gas gauge chip and therefore is not controlling the charger chip? If that's true, do I need to terminate the charge by manually, and quite literally, pulling the plug on the battery pack and once the profile is completed, then be able to control the charger IC with the host? I would like to make sure that my profiling of the battery is correct and I am not under/overcharging the battery before the discharge is started.

My question is how do I configure my setup to be able to automatically terminate the charge when the battery is fully charged?

1. How is the termination voltage set for the end of the charge process? (aka. how does the Charger Know when the battery is fully charged and stops pulling current?)

2. Should the current being pulled slowly reduce as the battery approaches max voltage level? Our Setup is currently pulling almost 1 AMP to charge the battery all the way to its peak voltage (7.5V) and does not stop.

3. How do you configure other shutoff methods for the charger such as Delta V or Delta T (aka using voltage dropoff or temperature to decide when the battery is at full capacity)?

Help would be greatly appreciated, please ask if further information is needed.

Additional information

Charger: bq25703A

Gas Guage: bq34110

Battery Management studio v1.3.54 used to read/write from charger IC