Other Parts Discussed in Thread: BQ24074
Hi,
While testing the BQ27441-G1A we are seeing an issue where gauge says State of Health status is Ready, yet the reported State of Health and Remaining Capacity is wrong: It reports approx. half of the design capacity, while we estimate the true value somewhere between 90 - 100 %. We have configured the BQ as recommended in the Quick Start Guide www.ti.com/.../sluuap7.pdf (except the NVM-part, yet we do not power off the BQ during these tests). We also notice in the final charge before going SoH goes to Ready, the State of Charge jumps from about 60% to 100 % midway during taper charging (while charging at about 500 mA of 1 A max, cutoff at 100 mA). It leads us to believe there is something wrong with our configuration, yet double-checks have not revealed anything. We are testing a battery with two cells in parallell and the following parameters: 5200 mAh design capacity, 19240 design energy, 2700 terminate voltage, and 520 taper rate (BQ24074 charger at defaults).
If it possible to point us in a direction of troubleshooting based on this description we would appreciate it. Regardless we have some questions:
1. The quick start guide section 4 states a guard around the taper rate is advisable. However, looking at other doc., implementations and forum posts, this is typically not utilized. Could you confirm if the guard is necessary? Is the 15 % in the example an appropriate value?
2. What accuracy can we expect of the SoC before any significant learning / charging cycles have been conducted?
3. When the SoH state reports Ready, can we use this to infer the SoC and other values are now fairly accurate?
Regards
( I re-posted this as the original post was marked with wrong part number)