I know this is a completely different class of device, but even though my FitBit can last a few days without recharge, the more important thing is that it can g

I know this is a completely different class of device, but even though my FitBit can last a few days without recharge, the more important thing is that it can get a full day's charge while I'm in the shower. A 24 or 36 hr battery that recharges during a 15m shower I imagine would work for most people.