Lithium Ion Polymer Battery Introduction

I.The components of Drone Lipo Battery:

The lithium batteries used in UAV and Drones: lithium cobalt oxides, we call it Lithium polymer battery.

Depend the different materials of the batteries ,There are several systems of lithium batteries:lithium cobalt oxides, lithium cobalt oxides,lithium cobalt oxides, and Ternary material(NCM),And it also has another materials,But the above materials refer to anode materials.

II.The features various battery:

1-lithium iron phosphate is too heavy,and with a low voltage,so it's not usually used as a UAV battery.

2-The lithium manganate discharge platform height, but it has its inherent defects. In addition, the discharge rate is low, it's not be used as a UAV battery.

3-The production technology of lithium cobalt oxides is the most mature, and the discharge rate can be increased. It is the best choice for UAV battery, And most of the batteries for Drone and UAV use this. but its disadvantage is too expensive. Even expensive but still use forAgriculture Spraying Drone, Industrial Drone and Racing copters.

4- Ternary material(NCM)is cheaper, but it is made of three different materials, so there will be many mix proportion,such as 3:3:3, which is the best ratio for UAV battery.It also has another ratio like 4:3:3 , 8:1:1 .... ect,that`s means different ratio, different characteristics ,First of all, nickel is the most active (it is the first generation of lithium-ion battery , but all failed because it is too easy to fire and explode) Cobalt activity is slightly less active than nickel, but it is very stable, which is what we call lithium battery.Manganese has low activity, but the structure is stable, the disadvantage is that it will lead to a short life,Such as 8:1:1 refer to nickel 8 cobalt 1 manganese 1, the sort order is nickel,cobalt manganese (or called NCM)

Because the ternary material can mix proportion, nickel has Large capacity, cobalt is stable, manganese has stable structure and high platform. So you can mix it due to demand. The discharge multiplying power of ternary materials cannot be very high. Manganese always drug their feet. Nickel is too dangerous to be limited. In addition, because it is a mixture, there is no flat platform.

See the below figure for the meaning of platform:

lithium cobalt oxides battery discharge curve

Ternary material(NCM) Battery discharge curve

Therefore, the battery with discharge platform has better power durability when flying, and the voltage drop is slower than the ternary battery. In order to solve this problem, many ternary batteries now use the 14s method, which aims to reduce the voltage drop when the discharge reaches half, so as to extend the flight time, but the problem is that the charger needs 14s.

Another way is high pressure! But it's only a little higher than a normal battery. The battery we use is 4.2V full charge, and the high-tension battery is 4.3v to 4.35v full charge, but it is basically more than 4.3v. The negative side of high-tension battery is also the requirement of charger, and less security. At the moment DJI MG series use this technology for it`s Smart batteries to get more battery life.

III.The discharge limit of UAV battery:

According to the data provided in practice, when the discharge at 1C within 95% , the service life will not be affected, which is about charging and discharging cycles.

The discharge is about 3-5c in actual use, and in 85% ~ 90% does not affect the service life, and lower discharge will make the service life more than 200 cycles, sometimes around 300 cycles.

The life of smart drone battery is longer than that of non-intelligent battery. Because It has the management module with function of self discharge and charging protection.

The service life of 12s battery is longer than that of ordinary series 6S battery. Because the whole machine balancing of 12s is better than that of two independent 6S.