That's really only about the last thing I worry about when deciding on a portable game system. I lived in the original GB and GameGear days when 4 - 6 batteries would last you maybe 3 hours. Maybe. But my PSP lasts way longer than 5 hours. I think it averages 8 - 10 hours. Though its internal estimates sometimes get as optimistic as saying I could go for around 15 hours. But I only charge it every couple of weeks. I keep the brightness on its lowest setting. And rarely have the sound turned up past a couple of bars. Its usually muted, actually. So I'm probably getting pretty optimum efficiency out of its battery life