Can not do this, it seems that it can be charged, because the USB interface voltage is 5V, the battery voltage normally changes between 3.6 and 4.2 (lithium battery voltage 3.6V shows that it needs to be charged, 4.2V battery is fully charged), the direct connection between the two is a voltage difference, so it can be charged, but this charging, There is no lithium battery constant current charging dedicated voltage detection and charging circuit, if directly connected, short time is fine, there will be no damage, long time combined charging, battery voltage to 4.2V will not stop charging, it will make the lithium battery final voltage overvoltage, lithium battery damage, or heat explosion-proof ring broken scrap, or explosion-proof ring blocked directly exploded.