LiPo 2s (7.4v) rechargeable batteries provide the best performance. Something similar to the one from the EZ-B store will do, just keep in mind the higher the mAh, the better it will perform under load, more play time also .

Also the V4 no longer have built in voltage regulator. If you want higher voltage like 12v, an external regulator will be needed. Or can play it safe and use a 7.4v that can easily support servo and sensors. But certain sensors like the HC-SR04 only play nice with 5v, that's where you datasheet come info play .

Ok and So would you recommend using 1100, 2800 or 3000 maH batteries for safe use?

If 3000mAh is in your budget by all mean go for it. Higher amperage equal higher play time. A battery’s capacity determines roughly how long a battery will last at a specific voltage given a specific discharge rate. 3000mA = 3000/1000 = 3Ah... It mean your battery would provide 3amp per hour. Yes it is safe.

Kool thank you for all Your assistance, you have been very helpful =)