A 18650 is a 3.6/3.7 volt lithium ion battery about 50% thicker than a AA and twice as long. They range from 2000 to 3000 mAh. Strong flashlights nuke a single 18650 in under 90 min like I said earlier. Magicshine and numerous other systems might use a battery pack with anywhere from 2 to 6 18650 cells in them. (There are several other lithium options too.)

My cheap-o charger gets them fully juiced in 2.5 hours.