Originally Posted by
CudaMan
- Solar. Many can store solar energy for weeks, maybe months. But leave it in the dark too long and it'll eventually stop. Indoor light is enough to keep it charged for a while. Citizen calls their solar watches EcoDrive and Seiko calls their line Solar.
- Kinetic movement. A weight (sometimes visible through a clear case backing) moves in a circular motion inside the case as you move around during normal daily activity and the watch movement stores energy in a spring (someone correct me if my assumption is wrong). Leave the watch unworn for long enough (days or weeks I want to say) and it'll stop. You can move it around 'manually' for a few minutes in your hand to restart it.
- Old fashioned winding of the crown. I've never owned one of these so I cant' comment on power reserve. Some fancier watches have a sub-dial that tells you how much power is stored in the mechanism.