Other Parts Discussed in Thread: BQ25750
Tool/software:
I'm implementing bq25798 (5A max lithium battery charger) to charge a 4S battery pack.
The application will also have a BDC motor capable of 6A max which I hope to operate during charging.
My first question is on the maximum input current to the Vbus pin according to datasheet page 8 table 8.3, which says 3.3A maximum. It looks like this will actually be the primary limiting factor for max charging rate compared to the 5A output, especially for a 4S (~16.8V charging voltage) battery pack, correct? If this is true, a device with external FETs may make more sense.
Either way,. I have a few options of how to connect the motor and am unsure how the IC might behave under different circumstances.
1. I connect the motor load to SYS, which I believe is limited to 5A discharge from the battery to the SYS pin. In this situation the total input power is still limited by the 3.3A Vbus input current, and the output power is the sum of the battery and motor load.
2. I connect the motor load directly to the battery itself external from the bq25798. Now the motor current is only limited by the battery discharge current.
My main question is how will the bq25798 behave during combined motor and battery operation? If the IC is providing a fixed 5A output, I'm assuming this will simply be dynamically shared by the battery and motor depending on how the motor load is changing. Wouldn't this configuration interfere with the detection of charge termination or other battery sensing during charging?
