I am trying to build a 10S3P Li-Ion charger based on the LTC4020IC. I am using the DC2044A demo board, which I modified to adapt it to my charge current (4.2A) and my input (55V max) / output (Li-Ion 10S3P) voltages.
Everything works great, I am abble to completely charge my battery, and the transition from CC to CV is done around 41.5V (I set up 42V as float voltage).
But I have a problem with the preconditioning mode, which should stop when the battery is above 29.4V (1.75V on FB pin), unfortunately it only stops when the voltage is above 34V (2.0V measured approx on the FB pin).
I don't have the possibility to set by myself the preconditioning threshold, do you have a clue on what is happening here?
Here are the relevant components modified on the demo board:
R8 = R9 = 680k, 0.1%
R10 = R11 = 43k 0.1%
Other components modified:
M2, M3, M4, M7: BSC098N10NS5
RCBR1, RCBR2: 10mOhms
L1: 22µH (WURTH 74435572200)
C14,C18,C27,C28: operating voltage at 63V minimum
C17,C15: operating voltage at 63V minimum
C19,C20: 1uF 50V
D7: 6V 0.1A Zener
And the header JP1 is of course set to CC/CV
Thank you for your help.
I look forward to hearing from you,