Hi TI Support,
I'm working on developing an automated test system for our batteries. We use the BQ20Z95. We've discovered that the temperature reading returned from the battery is not a good indication of whether the thermistor hardware is good because it will return the highest value of the three temperature sensors (int, ext1, ext2). It seems as though a defect can be present that is either ignored or returns a value much too low so it is not reported.
When I calibrate the defective battery in question using the TI evaluation software I receive an error message (5026) which indicates an overflow occurred with a Temp Sensor. When I manually perform calibration through the TI software by sending each byte individually it seems to work.
The process I use is the following:
Set Calibration Mode: send 0x00 0x0040
Write the actual temperature: send 0x62 0x0B99
Start calibration: send 0x51 0xC038
Read back 0x52
0x52 will return 0xC000 which would seem to indicate calibration completed.
I'm unable to read the Battery Status register while in calibration mode so I can't determine the results which I assume would be reported from bits EC3, EC2, EC1, EC0.
After I send 0x73 to get out of calibration mode (I'm not storing the calibration results - there's no difference if I do though) the battery status register returns 0's for bits 0, 1, 2, and 3.
So how do I detect when a calibration fails??
Thanks!
Matt