Part Number: BQ40Z50-R1
Hello Everyone,
Our 4S4P LiFePO4 20Ah/256Wh SBS battery manufacturer from China has switched from bq3050 (NRFND) to bq40z50-R1 for the new lot we just received.
Those batteries were programmed as 128Wh batteries with a 0.5 current scaling factor. So that displayed % RSOC is OK, and the manufacturer can use the same firmware for their 512Wh batteries (40Ah > max 29Ah for bq40z50).
The problem is that we use smart chargers: reading the battery chemistry sets the charging voltage, and reading the design capacity sets the charging current.
Thus the manufacturer sent us a new .srec file along with the Unseal and Full access codes. We've been loading this new .srec file in all our new batteries, but some batteries won't display a Full Charge Capacity of 20Ah, although we discharged them to a few percent RSOC (Vbatt below 11V), let them at rest (Relax) a few hours, then recharged them to 14.6V. Of course we checked the current calibration, it's OK.
We put those under rating batteries on an electronic load after charging them to 14.6V, and indeed they displayed at least 270Wh capacity each.
What did we do wrong?
Can Qa_max be adjusted upwards by the bq40z50R1, or can it only be lowered ?
Will an export of the gg.csv from a "good Full Charge Capacity" battery, and then an upload to the under rating batteries solve the problem?
Please let us know.
Thank you.
Regards.
Matthieu