This guide is about lipo battery is for RC beginners(if you are a Rc car, UAV, drone, Rc heli and some other Rc lovers, this article may give you some help), but if you are a old players, you can share this guide to newbie. I wrote this article mainly to tell you what’s the lipo battery and what all the numbers mean on the lipo battery. If you know these, these guide will give you some help in future, these are some basic knowledge about battery or RC.
First I will introduce the Lipo battery-What is a LiPo Battery?
A LiPo battery powers all of the electronics, and motors on your drone. The difference with LiPo batteries and the ones you would use in your TV remote is the chemicals used in the battery. LiPo batteries are based on Lithium Polymer chemistry (hence the name LiPo) which allow these batteries to have a very high energy density compared to other types of batteries. A battery with a higher energy density will be able to hold more energy compared to another battery of the same weight which is why LiPo batteries are commonly used with R/C aircraft and drones.
There are other types of batteries such as nickel cadmium (NiCad) or nickel–metal hydride (NiMH), however these are seen as older battery technology and are not really used anymore because they are very heavy and dont hold much energy compared to LiPos.
A LiPo battery is constructed from individual cells, where each cell consists of some metal and chemicals packaged together to generate an electrical charge. By connecting these cells together in various ways we are able to make different LiPo batteries with various voltages, and capacities. More on that later on
What’s the numbers mean?
We will now discuss what all of the numbers mean that specify a LiPo battery. This will help you to know what you are buying and how to choose the correct LiPo for your application. This is a Gens Ace 2200mAh 11.1V 25C 3S1P Lipo battery.
A battery is constructed from rectangular cells which are connected together to form the battery. A cell which can be considered a battery in itself, holds a nominal voltage of 3.6V. By connecting more of these in series, the voltage can increase to 7.2V for a 2 cell battery, 11.1V for a 3 cell battery and so on. By connecting more batteries in parallel the capacity can be increased. Often you will see numbers like 3S2P, which mean the battery as 3 cells (3S) connected in series, and there are 2 cell sets connected in parallel (2P) , giving a total number of 6 individual sells in the battery.So the number of cells is what defines the voltage of the battery. Having a higher voltage means the battery can provide more power to drive bigger motors, however more power does not necessarily mean the battery will provide energy for longer, that is defined by the battery capacity.
Each cell in your LiPo battery has a nominal voltage of 3.7V. However when you use the battery the voltage will drop down, but it is important not to let this minimum voltage drop below 3.0V. Similarly you must ensure that the maximum voltage for a lipo cell is 4.2V. If the voltage of any cell in your Lipo battery goes beyond this range you can cause the chemicals to become unstable which can cause a fire so for this reason Lipo battery chargers are designed to ensure you only charge each cell to 4.2V. Similarly most ESC’s have a cut off voltage which turns off the motor when the voltage of your battery gets low to avoid discharging it too much.Some multi-rotor ESC’s have this feature disabled as a motor suddenly turning off would result in your drone crashing. However most multi-rotor flight controllers have a way to monitor the battery voltage and warn you before it gets too low.
The capacity of a battery is a representation of how long it can provide energy for, often quoted in mili Amp hours, (mAH). The bigger this number, the more capacity the battery has, so it can run your motors for longer. However the higher the capacity of a battery, the heavier it is so there is always a trade off between the battery capacity and weight for your aircraft.
The discharge rate is a very important specification to check when buying a battery. This number, also known as the battery C rating (or continuous C rating) defined how fast you can extract the energy from your battery. If your motors draw more energy that what you battery can provide, you can possibly damage your battery which can result in you crashing your drone. We discuss how to ensure the discharge rate is sufficient for your drone in our how to choose a LiPo Battery for your drone guide. To work out the actual current in Amps you simply multiply the capacity by the C value. So a 2200mAh battery with a C rating of 25C would have a continous current output of 25 x 2.2 = 55A continuous current output Some batteries also specify a burst discharge rate (burst C), value represents the extra discharge the battery can provide for short periods of time usually 15-30 seconds.
These are the lipo batteries basic knowledge, and after know these, you’d better to know some knowledge about How to charge and store your batteries?