The energy bar can maintain a constant heal for 16.67 seconds before needing to sit and recharge.
Mana bar at lvl 1 can maintain for roughly 43 seconds.
At lvl 20 it can maintain for roughly 110 seconds.

Please Help.
Thanks !

I didn't find the right solution from the internet.
References:
-https://us.battle.net/forums/en/heroes/topic/20758688868
-B2b Advertising Examples