Lithium-polymer battery - what is it and how to charge Li-Po?

Although most drones are relatively lightweight devices, keeping them in the air requires efficient energy sources. Many models use lithium-polymer, or Li-Po, batteries, which are distinguished by their lightweight and efficient operation. What exactly is a lithium-polymer battery, how it works and what you need to know about charging it?

What is a lithium-polymer battery, what advantages and disadvantages it has?

A Li-Po battery is a special type of lithium-ion battery in which the the electrolyte is in the form of a polymer - instead of the traditionally used chemical solution. This key difference translates into several important properties that distinguish this type of battery from Li-Ion batteries. The most important of these is the ability to quickly give off electricity. As a result, the polymer battery is a a common sight in drones where high power and speed are important, but as a result, it has a lower density than known Li-Ion. Here are the biggest advantages and disadvantages of Li-Po batteries:

• Capable of rapid current return - especially needed in racing drones, where high power consumption is required.
• Lower density (150/200 Wh/kg) - this means that a Li-Ion of the same capacity will be lighter (this is different when you have a Li-Ion battery in the form of cells such as 18650/21700).
• Greater sensitivity - li-Po batteries are less stable and when damaged there is a good chance of the pack catching fire/exploding.

Lithium-ion or lithium-polymer battery - which is a better choice for a drone?

When comparing Li-Ion and Li-Po batteries, there are several important differences that arise from their design and translate into their intended use. The advantage of lithium-polymer batteries is, first of all, fast current output. This makes them a great choice for drones where maximum power is key. As a result, Li-Po batteries are mostly used despite their smaller capacity, and less stability.

How the lithium-polymer battery works?

A typical Li-Po battery consists of several cells connected in series. In the case of drones, it is common to find batteries with configurations ranging from 1S (3.7V) to 6S (22.2V) and even 8S(29.6V), which provide the right amount of power for engines. The battery itself, on the other hand, consists of three main components:

• positive electrode (cathode), that is, the lithium material responsible for storing the cargo
• negative electrode (anode) - stores lithium ions during charging
• polymer electrolyte - Is responsible for the flow of ions between the anode and cathode

As the battery discharges, that is, while the drone is operating, lithium ions move from the anode to the cathode, generating an electric current. During charging, this process takes place in reverse - from cathode to anode.

Lithium-polymer battery - how to charge it?

Regardless of the differences between a lithium-polymer battery and a lithium-ion battery, in both cases proper charging is crucial to ensure safety and long battery life. What to keep in mind when charging Li-Po? The basic issue is use of a correctly selected charger - for Li-Po batteries are specially designed with voltage monitoring and overcharging avoidance in mind. It should also be borne in mind that the voltage should be in the range of 3-4.2 V, and exceeding these values (in both directions) can lead to permanent damage. It is also important to avoiding overheating. Charging should be done at room temperature.

Lithium-polymer battery life. How to make it longer?

How long is the lithium-polymer battery able to serve? The lifespan depends primarily on how the battery is used and maintained. It's worth sticking to a few basic rules, such as keeping the charge level around 3.7V on the cells if the battery is not used for a long time, as well as avoiding deep discharge (less than 3 V). Protection from moisture and mechanical damage is also important.

You also need to be careful about the conditions of use of the drone itself - extreme temperatures can be especially dangerous, which shorten the life of the battery. During the winter period, before flying warm up the battery before use. The best solution is to warm the battery with room temperature indoors or use your own body by putting it in your pocket or under a layer of clothing. Zdeciding phe battery and better affect its use. Learn more about using batteries in cold weather in our article: Is the cold destroying your batteries? Here's how to avoid it

In addition, it is always a good idea to keep an eye on the charge level indicator and monitor any unexpected changes, as well as the battery messages. In addition, we recommend using only tested batteries straight from the manufacturer or trusted suppliers.