Lithium Polymer batteries (with the exception of RC LiPos) last much longer than lead acid batteries. LiPo batteries are usually only rated for a few hundred charge cycles but LiFePO4 batteries keep going after thousands of charge cycles. Every manufacturer rates their batteries differently, but most LiFePO4 ebike batteries will be rated for between 1,500 to 2,200 charge cycles. Gens ace is the professional lipo battery manufacturer in the RC & UAV market, their product range from 1s lipo to 6s lipo, such 7.4v 2200mah, 5000mah 3s lipo, 11.1v 1300mah lipo battery, ect. Today we mainy talk about 2 cell and 3 cell lipo battery.
A 2-cell LiPo battery has the same relative voltage as a 6-cell NiMh or NiCad type battery that is 7.4 volts. Running a 3-cell LiPo battery will give you the relative equivalent voltage as running 9 to 10 NiMh or NiCad cells. Be sure that your speed control is capable of running this higher voltage or damage may occur. Electric motors are capable of running different amounts of voltage. However, more voltage can and most likely will generate more heat in the motor. You will get much higher speeds, but you are starting to push the limits of the motors.
They wind up giving you the same run time, but the 3 cell has a much higher voltage output to the motor, so you wind up with more overall power, or watts, than you would with a 2 cell.
Example: 2 cell 7.4 volts x 10 amps = 74 watts ---- 3 cell 11.1 volts x 10 amps = 111 watts
The only real difference, besides voltage obviously, is the weight of the pack. The 3s 2200mah is going to weigh more than the 2 cell if they are both 2000mah. Just depends on how many total watts you need for performance. That will tell you if you can get away with a 2 cell, or if you need the 3 cell.
For arguement sake, you would probably be able to run the 3 cell at a lower throttle setting (less amps) than the 2 cell lipo battery to get the same performance, since the voltage is higher, leading to more watts. So I would suppose the 3 cell might actually give you a little longer run time. Depending on how much throttle you need. Using the example above, you could run the 3 cell setup at about 2/3 the throttle, or 6.6 amps and still match the 2 cell in terms of watts.
Ok, the following are two products about 2 cell and 3 cell lipo battery from Genstattu.com
Gens Ace 2 Cell LiPo packs are ideal for all Slash, Slash VXL, Slash 4x4 VXL, E-Maxx Brushless, E-Revo Brushless, and Spartan models. Power Cell LiPo packs are engineered to give the punch and on-demand power to reach the top speeds Traxxas models are built to achieve. Premium LiPo cells developed specifically for Traxxas feature over sized discharge tabs for maximum efficiency.
2250mAh 3s 35c Lipo Battery
Gens Ace lipo batteries provide you with great performance for your multi-rotor air-frames and planes. This lipo's 35 "C" rating is well suited for multi-rotor applications by balancing performance and weight. This Gens ace lipo maximizes flight time with minimal voltage sag. The all black battery design with the Luminier brand will look great on any air-frame! Whether you've got a crawler, biped or rover, you're going to need a battery pack to get your robot moving on its own. Lithium Polymer batteries are a great choice for robot batteries because they have great capacity-to-weight ratios, giving you lots of power for very little weight. Our 3s 11.1V 2200mAh 30C LiPo Battery is a great medium sized battery that can discharge up to 66A continously!
It is important that you pay attention to gearing; incorrect gearing along with prolonged runs using high-capacity batteries can result in excessive heat, causing it to swell and possibly catch on fire or explode. This will overheat the ESC itself and damage it and possibly overheat the motor as well. These possibilities are not strictly limited to three-cell LiPos.