Lipo batteries are getting more and more popular. They offer a few advantages over standard NiMH batteries. They are not prone to dying faster in normal cold temperatures. So even in the New England winter, these batteries will last as long as they would in the summer. They also offer a higher energy content and more efficient, high rate discharge over NiMH batteries. You do however have to look after LiPos more. The proper operation voltage for LiPo Batteries is between 2.8v(close to dead) to 4.7v(fresh off the charger), per cell. If a LiPo pack is discharged passed 2.8v, chargers are programed to refuse to charge the battery. This is for your safety and you should never force charge a lipo. The easiest way to protect your LiPo is to buy a voltage tester and test your LiPos every few games or few hours. These Turnigy Nano-Tech Lipos are some of the best on the market and come with a slightly higher discharge rate than other airsoft lipos, making them better for high torque motors.