Locked store content from the 1.07 EBX dump

Power refresh does have diminishing returns, and as such, you can never have instant recharge of powers. Take, for example, Charge, which is very easy to get more than 100% recharge speed from the Rank 3 and 6b evolutions. This gives 110%. The formula for the modified recharge is base recharge*(1/1+(sum of recharge bonuses)). For the Charge example, that would be 1/(1+(.35+.75))= .476. Multiplying this by the base recharge of 8s leaves you with a new recharge of 3.8s. 

A good rule of thumb for recharge is 50% gives you 2/3 of the normal recharge, 100% gives half and 150% gives 40%.