Greetings. We are using a bq24251 (in i2c mode) in a device that is in production. Due to an unrelated issue, a small percentage of these devices are discharging too quickly. The permanently connected 18650s we are using in these devices have over-discharge protection circuitry - the small percentage of our production lot that are discharging too quickly will discharge the battery to the point where the over-discharge protection circuitry has tripped. We have found that a few (not all) of these defected/over-discharged units will not recharge when a USB connection has been made. We confirmed that the issue follows the PCB and not the battery - in other words the bq24251 seems to be at fault, not the over-discharge protection circuitry. I am wondering if the bq24251 is not sensing the presence of the battery since the over-discharge protection circuitry has tripped (bq24251 and i2c connected MCU are powered down), but I can't explain why this appears to be occurring on only a small percentage of boards. Can someone explain the battery detection process if the bq24251 is brought up from dead? Do I need to prompt (over i2c) the "AnyBoot" process upon startup? If so, why do most units work without this prompt? The datasheet appears to be lacking in this department.
Any help will be greatly appreciated.
-Chris