I don't remember encountering such a mechanic.
But I also don't quite remember how the power mechanics work; Does it only alter the recharge/reload rate of weapons or also the max charge?
If it is the latter, it would be enough to set the normal maxcharge for e.g., a pulse weapon 25% (or 20% or whatever) below the discharge rate (or what it is called).
If it is the former, a little script would need to check the power distribution and set e.g., the maxcharge depending on that.