When we get a lipo battery, you can see there are some parameters on its package, what are their mean? For many beginners you may don’t know, but they are very imortant, because lipo battery is a very important for drones, this artice is tell you what are these lipo battery parameters mean.
For example: here is a Tattu 1300mAh 4S 95C lipo battery.
Lipo Battery Capacity
The 1300mAh on the picture means the capacity of the lipo battery. Capacity is used to measure how much power a battery can hold.and the unit of capacity is milliamp hours (mAh), which means 1300mAh can be put on the battery to discharge it in one hour. Milliamp also can be converted to amps(A), here is the conversion:
1300mAh=1.3 Amp Hour(1Ah)
Generally, capacity can determines how long you can run before you have to recharge. A larger capacity pack may give you longer flight times but being heavier it will adversely affect performance. But it`s also influenced by the speed, the more quick you can flying your plane, the less time your flight time is. Because high speed means you need more power to drive your plane or others, so your power lost quickly.
Lipo Battery Voltage
A LiPo cell has a nominal voltage of 3.7V, and a lipo cell = 1 cell = 1S = 3.7V. For the 14.8V battery above, that means that there are four cells in series (which means the voltage gets added together). This is sometimes why you will hear people talk about a “4S” battery pack – it means that there are 4 cells in Series. So a four-cell (4S) pack is 14.8V, a three-cell (3S) pack is 11.1V, and so on.
3.7V battery = 1 cell x 3.7V= 1S battery
7.4V battery = 2 cells x 3.7V= 2S battery
11.1V battery = 3 cells x 3.7V= 3S battery
14.8V battery = 4 cells x 3.7V= 4S battery
18.5V battery = 5 cells x 3.7V= 5S battery
22.2 V battery = 6 cells x 3.7V= 6S battery
29.6 V battery = 8 cells x 3.7V= 8S battery
37.0V battery = 10 cells x 3.7V= 10S battery
44.4V battery = 12 cells x 3.7V= 12S battery
The voltage of a Lipo battery pack is essentially going to determine how fast your vehicle is going to go. Voltage directly influences the RPM of the electric motor (brushless motors are rated by kV, which means ‘RPM per Volt’). So if you have a brushless motor with a rating of 3,500kV, that motor will spin 3,500 RPM for every volt you apply to it. On a 2S LiPo battery, that motor will spin around 25,900 RPM. On a 3S, it will spin a whopping 38,850 RPM. So the more voltage you have, the faster you’re going to go.
When you select lipo battery, you need to know your motor of rc model, Voltage has an impact on motor, and motor influence the speed. The higher voltage is, the higher power( P) of the motor is, and here is the formula:
“P” is power, “U” is voltage, “I” is current. As you know, the voltage influence the power of the motor of battery, and the power has an impact on the RPM of the motor, that means speed. So in some racing, pilots need the batteries are of high voltage to meet the needs of their rc model to get a high burst.
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 3.7V. By connecting more of these in series, the voltage can increase to 7.4V for a 2 cell battery, 14.8V for a 4 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 4 cells (4S) 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.
Discharge Rate (“C” Rating) is simply how fast a battery can be discharged safely. In the RC LiPo battery world it is called the “C” rating. A battery with a discharging rate of 95c, that means you could safely draw it at the 95 times more than the capacity of the pack, a 10C pack = 10 times more, a 20C pack = 20C times more, from above the picture, you can discharge at 95 times more than 1300mAh, here is the calculation below:
95C = 95 x Capacity (in Amps)=95*1300mAh=123500mAh=123.5Ah
From the theoretical stand point, if you discharge you battery at a 2600mAh, so the 1300mAh of battery pack can be exhausted in half an hour. From above the calculation, draw battery at 123.5Ah, so this battery pack will be draw out in 0.63 minutes.
Sometime, you would be required to get a battery of high discharging rate, usually in a race, such as FPV racing, you must in a high speed and win a race. So the higher “C” rating means your thing can get a higher burst in a moment. So, you know, why so many pilots attach such a great importance into the high discharge rate. But the disadvantage of the high “C” rating is it may get heavier and affect its performance. And it may more expensive than the lower one.
Drone battery connectors
There are many common connectors include Deans, XT60, EC3 and JST etc. What is the performance impact of these connectors? Connectors you are using will also be able to handle the current.
Below is connector current ratings:
- JST connector – up to 5A
- XT60 connectors- up to 60 Amps
- Deans – up to 60 Amps
- EC3 connector – up to 60 Amps
- EC5 connector- up to 120 Amps
After know these lipo battery basic parameters, you may interested in how to choose lipo battery for your drone.