Hey I recently took apart one of those manually crank LED flashlights, and noticed that the battery was 3.7V lithium ion, does anyone know a way to adapt the crank flash light to charge a bigger battery like maybe a 9V.?

Thanks

 

Wouldn't this depend on how much raw voltage the little generator in there is capable of ?

 

How about 3 AA NiMH batteries, they would store much more power and the voltage is about right. You could use a boost converter with this if you need higher voltage out.