I have this custom PCB witha CN3722 module. I charge two 18650 batteries. Resistors XVR7 and XVR6 are calculated for 8.3 volts. The charger charges the batteries and the "done" LED turns on when the voltage of the batteries gets to 8.3v.
The problem is that it doesn't stop injecting current after the stop charging condition.
If the input voltage increases, more current goes to the batteries.
The solar panel has a maximum operation voltage of 18.5 volts.
The problem is don't stop of inject current after the stop charging condition.
This is how the P channel MOSFET should be connected (from the CN3722 data sheet): -
Your circuit has the P channel MOSFET reversed - note the bulk diode direction in your schematic. Its always going to conduct current to your battery i.e. there is no control: -
change the MOSFET to one like the AOD4185?
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The problem is don't stop of inject current after the stop charging condition. - if you want further help with this, raise a new question where you will attract many others into helping you find a way around this. Are we finished here?
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But Andy saw it first. The FET must be a PFET and your circuit is charging thru the body diode with DS reversed so Source is on the higher voltage side
If the CSP voltage drop does not reduce to 5% of CC current, such as when an external load is on battery at the same time, it will not shut off.
5% of CC is the typical shutoff trigger threshold (+/-50%).
Sense R= 0.04 Ohms thus (for example without looking up datasheet) if V(BAT-CSP)= 50 mV which is a typical sense voltage at max current (CC) then I max is 50mV/0.04ohms=1.25 Amps and 5% of this is 62.5mA and 2.5mV. Make sure your noise is low by a careful short twisted pair of wires.
Now looking at the datasheet, I see the current sense varies with low voltage to charge slowly at first then switch to 200 mV sense voltage thus my assumption was close and the max current is 4x what I said or 1.25A*4=5A which agrees with spec.
Also make sure your PCB traces are like this
