Lithium-ion battery charging circuit is shown as above. When it starts to charge. The battery voltage is below 8.4V, IC1`s output has no output. Q2 off, LM317 work in the constant current output. When the battery voltage is increased to 8.4V, Q2 turns on, Q2 controls ADJ-side, so that the output voltage of IC2 significant declines and make the charge curre..