Lipo battery is used as a power source for quadcopter due to high power to weight ratio. NiMh is more cost-effective, but heavier than Lipo, hence it is not preferred. Lipo battery can be found in a single cell (3.7 V ) in a pack of over 10 cells connected in series produces 37 V. A popular choice of battery for a quadcopter is the 3SP1 batteries with terminal voltage of 11.1V. Battery has peak discharge rate of 25 times the rated capacity and a capacity of 5000 maAh will deliever maximum current of 25 C × 5000 mAh = 125 A.
The batteries for RC motor project can be changed depending on what you want to use. I decided to try and keep this bot relatively lightweight by using Lithium Polymer batteries, abbreviated Lipo. Lipo batteries are typically 3.7v per cell and lightweight compared to lead acid for their charge capacity. These batteries must be charged with a Lipo-specific charger and must not be discharged beyond 3.0v per cell or risk catching on fire；so only use these batteries if you understand how to handle them.
Many online hobby shops have excellent pricing on Lipo batteries and chargers, making them affordable even on a budget. I found Gens ace 4s lipo for only $15 each. They have a 20c discharge rate, meaning that by itself, this battery is capable of discharging approximately 60 Amps continuously (3Ah × 20c = 60 A continuous). If you use two of these packs in the parallel, the discharge rate doubles to 120 Amps (6Ah × 20c = 120A).
To get more power to the motors, I decided to place two packs in series to make 22.2Vdc and 3000mAh. You can buy as many of these as syou can afford and place several 22.2V (series packs) in parallel to achieve 6Ah, 9Ah, 12Ah, and so on. The Lipo battery packs weigh only approximately I pround per set, whereas a comparable SLA battery weighs approximately 6 pounds. Of course, the Lipo batteries are about twice the price of a comparable SLA battery, but you should buy only as many Lipo batteries as you need Amp Hour capacity to decrease the weight on your robot.
Alternatively, you can use Sealed Lead Acid batteries to get around having to buy a Lip charger only or worrying about over-discharging. Two standard 7.4v 2200mah lipo battery would fit nicely in this frame. As you can see from Figure 12-21, either type of battery has plenty of room in this frame.