BQ24650充电一直是1A，请教是什么原因

换了两颗Rdson较小的MOS管，电流能起来，请教是不是和MOS管有关系？

您好，跟Rdson有关系的。
The max charge voltage of your battery, and not the nominal voltage, as the output voltage of the BQ24650 IC should correspond to max charge regulation voltage of the battery. Depending on charge current, external components should be chosen accordingly to minimize voltage drop at the input (RDSon, fwd voltage drop of diode, trace impedance et). This is because you have small delta between input and output voltage, and you want to avoid the SLEEP threshold being hit, as this is the minimum delta between input and output voltage, for which charger can operate.