i am from india. I have a question. can i power up a 5 volt 4 channel relay module with a 5 volt 0.7-0.8 mAh wall type charger, which is basically use for charge the simple mobiles. If yes, then how i connect, i mean what will be the circuit diagram. which wire will be connect with the vcc and which wire connect with the ground and which wire is connect with the ESP8286. i am try to built a home automation project. Thank you very much. Please help me.
Short answer: No, probably not.
A Battery charger for a 5V battery probably generates more than 5V, and has control circuitry that measures the charge level of the battery. You don't want any of that. You want a regulated 5V power supply with enough current to drive all 4 channels of your relay unit.
Look up the current requirements of your relays and make sure you use a regulated 5V supply that is rated for at least that much (or more) current. Ideally you want like 20% more for some "wiggle room".