Of course, what I'm proposing only makes sense if you tell the players when a power recharges.
If you wonder how would they know that, I think is a matter of choice of you, as DM.
If you want them to know, you can come up with several explanations.
For magical powers, you can associate it's available status to a glow in the creature eyes, hands, rod, etc.
For supernatural powers, as it was said before: glowing belly, dripping poison, etc.
For martial powers, a certain stance on the enemy, how he holds the weapon, exhaustion, etc.
If you wonder how would they know that, I think is a matter of choice of you, as DM.
If you want them to know, you can come up with several explanations.
For magical powers, you can associate it's available status to a glow in the creature eyes, hands, rod, etc.
For supernatural powers, as it was said before: glowing belly, dripping poison, etc.
For martial powers, a certain stance on the enemy, how he holds the weapon, exhaustion, etc.
