Dear colleague,
Our customer has been using bq40z50-R1 for the application scheme of 4S. Recently, they found some strange problems: when the battery pack is charged and discharged, the battery pack will automatically enter the SDM mode after being fully charged, and can't exit (1000 batteries are produced, about 50 of them have this problem);
Note: the battery model has been used since March 2018 (PCB and configuration file have not changed), with a monthly shipment of 1K, the problem began to emerge in December 2018).
Question 1: when charging and discharging, only connect the positive and negative poles of the battery, how can it enter SDM mode?
Question 2: if BQ40Z50-R1 enter SDM mode, why can't it exit after being fully charged?
Question 3: Normally, it is unable to communicate within SDM mode, but now it can communicate with computers via the EV2300
Note: three recovery pathways have been identified:
1. After the battery pack that entered into SDM mode is put aside for a period of time (30-60 minutes later), it will really enter the shutdown mode (at this time communication is unable), and then exit SDM after charging.
2. Re-download the configuration file of bq40z50-r1 can restore normal.
3. The battery pack with the issue can be restored to normal after sending RESET command;
Customer personal speculation: for some special reason, bq40z50-R1 tried to enter SDM mode but did not really enter (only closed MOS, not closed communication).
So could you please reply customer questions and explain this issue?
Best Regards,
Rock Su
