[Steve Plambeck]

I'm planning to simplify the recharge to 1:1. If a 12 mana Staff was empty, the wizard could put 12 ST into it at the rate of 1 per 15 minutes, the same rate as she'd be recovering her fatigue. So 3 hours later the Staff would be recharged, and the wizard would still be at the ST she had when she started recharging (no net gain or loss over whatever fatigue she had at the start).

You'd never want to recharge it during combat, nor when you were in a hurry to get your own ST back up, and you wouldn't always get the opportunity to do so depending on the campaign game.

One might allow that the wizard could sleep with the Staff in hand, recharging it as she dreamed, but again she wouldn't be recovering any of her own fatigue until the Staff finished drawing on her. I really like this latter idea.