Other Parts Discussed in Thread: BQ76930
Hi all
My company is implementing an E-Bike solution; the battery managment is comprised by:
BMS: BQ78350 and BQ76930
Cell: ICR-18650-22P 3.6V@2.2Ah
Battery pack configuration: 36V@6.6Ah 10s3p
As you can see, we are implementing a top side MOSFET configuration; this circuit is consuming 100uA to keep enabled the DSG and CHG MOSFET. We decide to implement an integrated charger module (always connected to the VBAT-GND net). This charger is always drawing something around 500uA from the battery pack.
I performed some lab validation (using a PSU rather than a battery pack) for the following parameters and everything was working ok.
The Protection\CUV\Threshold is set to 2800mV and the Protection\CUV\Delay is set to 2s.
The Power\Shutdown\Shutdown voltage is set to 2750mV and the Power\Shutdown\Time is set to 5s.
Five systems were tested at customer validation and we detected an issue. When the battery pack State of charge < 40% and stored some months, the discharge related to the charger module keeps discharging the battery pack and reducing the battery voltage. Unfortunately, we observed that CUV protection was not enabled, going directly to the Shutdown mode (the settings file is attached as xlsx file just for demonstration purposes). According to the BQ78350 TRM, the only way to wake up the BQ78350 from the shutdown mode is applying voltage at TS1 pin > VBOOT. This is not allowed to the final user. We are expecting a solution that can be able to use the charger module to wake up the system at any storage time.
1. Is this the right chipset (BQ78350 and BQ76930) for this application?
2. If affirmative, What do you recommend to start the debugging process?
Thanks in advance