A robot's current power amount is displayed by two blue bars at the sides of crosshair, all weapons and the Ghost Module draw a certain amount of power upon use. If power is used up or not enough power is available to use the currently activated weapons, it will blink red and sound a warning until enough power is restored. If you press the load out key of Ghost Module, the power displaying bar will do so too, but for Ghost Module, if you just keep cloak until power runs out completely , its de-active sound will replace all these(blink red and sound a warning). Power constantly regenerates, unless you're firing any weapons or your Ghost Module is actived.
After that, with the From Passive Power to Active Energy change on 30/06/2016, usage of the Weapon Energy Module had been altered from boosting the power regeneration speed passively to restoring a fixed amount of power instantly when activated, which also means it occupies a loadout slot currently.
When the Aeroflak Sentinel & Power Update was launched, the power of a robot depended on the CPU. "1750 CPU robots will see an increase of 25% power and power regeneration and 500 CPU robots will see a decrease of 25% power and power regeneration ...... The Power bar will always take 10 seconds to recharge from empty to full, but since the maximum Power depends on CPU, this effectively means Power regenerates 25% faster at 1750 CPU and 25% slower at 500 CPU." -- Robocraft official website. Then this is altered in the DAMAGE BOOST & CRF 2.0 update on 10/08/2017 to prevent the conflict with Damage Boost system. "The amount of weapon energy available to players will be 12,550 (the same amount for a 1,600 CPU Robot)" -- Robocraft official website.
Power consumption is a method for limiting burst damage of some bots while allowing for weapon variation and redundancy. Each weapon consumes power at different rates. For example, Lasers seem to consume minimal power at the cost of having less DPS, while plasmas will consume a full energy reserve in several seconds for high DPS in firing continuously.
Strategy-wise, it is important to manage your energy well. A common strategy is a laser/plasma combo, dishing out area damage with plasma cannons in quick succession (maxing out fire rate), depleting your energy, and then deal less but steadier damage with lasers. This is a good technique for continuously dealing damage with lasers and slowly regenerating energy at the same time (this is only true for the less power consuming lasers, wasps and hornets) or until you find cover.
Power consumption comparison
|Weapons Type||Power consumption per shot||Max Fire rate count||Fire rate||Power consumption per second|
|Single gun||Max||Single gun||Max|
|Chain Shredder||N/A(for the reason, check Chainguns)||1||20||20||1883||1883|