USB-powered Sega Nomad gives you near-endless game time
 

Sega's Genesis Nomad was always something of a compromise (it was running 16-bit console games on mid-1990s handheld tech), but the battery life was a particularly sore point: it took six AA batteries just to get 3 hours of play time. Wouldn't it be...

https://www.engadget.com/2017/05/28/...ess-game-time/