Part Number: BQ27421-G1
Other Parts Discussed in Thread: BQSTUDIO
Hello,
We are currently attempting a learning cycle to fit the BQ27421's parameters to our battery model.
We have seemingly followed all instructions given in this document, summed up in another post as :
"1- make sure you fully discharge the cell to empty(TermV) first (use a discharge rate of at least C/5). The range is between C/5 and C/10.
2- Relax for at least 5 hours. This is a recommended time for VOK and RDIS to clear, it can happen sooner.
3- charge battery to full. (typical charging rate C/2) Make sure IT is enabled, you can do this by sending a Gauge_EN() command from bqStudio if using it. VOK should be set now.
4- Relax for 5 hours again. VOK bit -> Same as step 2. At this point, QMax should be updated.
5 - Discharge the battery again to empty. Here your resistance table will update during discharge.
6 - Relax for 5 hours. VOK should be clear, REST flag set."
Our application uses a 4000mAh battery, charged at C/2 and discharged here at C/5.
In our case, the Update Status was set to 03 in order to start the cycle, and IT was allegedly automatically enabled since this is the case on the BQ27421 upon battery insertion.
After several tries, the output seems to be erratic and hints at a problem in our routine :
- we got an Ra table update featuring only 3 values followed by zeros for every following SOC point
- after performing the cycle again in parallel on 3 of our devices, it seems no update has occured at all, with QMAX and Ra values unchanged and QMAX_UP/RES_UP remaining at 0
Do you see any reason as to why this would occur after a learning cycle ?
Best regards,
Martin Monroy
