Dear all,
We are using the bq20z75 V 160 in a 4S4P LiFePo4 application. When I compare the default value of the Ra table and what we get I have noticed a difference.
A typical value will be < 100 (mOhm) increasing slowly to < 200 at gridpoint Ra12. At gridpoint Ra 13 there is always a "jump" in the value with some hundreds of mOhm falling at gridpoint RA14 to around the double of gridpoint Ra12.
Is this caused by the LiFePO4 type of cells we are using which has a much more flat discharge characteristic, - or is this normal ? Comparing the default Ra tables I see no jumps- only smooth transitions. The values I get is lower that the defaults and this I have expected because of a lower internal resistance compared to Li-Ion.
I would really appreciate any comments on this relative complex matter. I am interesting to learn if a glance at the Ra table would be a good input to diagnose the "health condition" of the indicidual cells.
Best regards
Kjell Ramberg