Hi everyone!
I'm trying to use the charge controller BQ24450 for 12V/7.0A lead-acid batteries. My schematics is the same as described in figure 10 (page 15 of the datasheet), as shown below. In my case, after calculations, the corresponding values for the components are: RISNS = 0.22R, RT = 806R, RP = 412R, RA = 215k, RB = 16.7k, RC = 46.3k, RD = 586k, Ccomp = 100nF, Dext is DB2431200L and Qext is BD244.
Since RISNS = 0.22R, the Ichg-max = 0,25/0,22 = 1,13 A. The external supply is a 18,5V/2.0A power supply. During charging, the battery is not connected to any load.
According to the figure 7 of the datasheet (shown above as well), if Vbat < Vth, then Ichg = Ipre. Otherwise, if Vbat > Vth, then Ichg = Ichg-max (while Vbat < Vboost).
However, I'm noting that when I plug the battery for charging, the current rises up to Ichg-max (even when Vbat < Vth) and after some minutes the current starts to fall quickly. The voltage seems to be okay, i.e., Vbat < Vboost at least.
In conclusion, my battery is never fully charged, even the Vbat is okay.
Does anyone have any idea?
Thanks in advance!
Best regards!
