LiPo batteries

Lithium Polymer batteries are widely used in various devices as in drones and multi-copter for its ability of recharging. When you look at the battery there are two sets of wires coming out of it. One set is a pair of thick wires, one red for positive and the other black for negative. These are usually used in RC electronics especially for multi rotors and planes where the battery is discharged quickly !

The other set of wires contains the number of black wires which is equal to the number of cells in the battery and one red wire. It is for balance usage i.e. equal amount of current is drawn from all the cells so at any point, the voltage of all the cells remain the same.

The voltage of the battery shown is the total voltage of all the cells included. Note that all the cells of the battery are connected in series. One cell of a battery has a nominal voltage of 3.7V . When fully charged it goes up to 4.2 V per cell. It can go upto 3V at a minimum. If it goes below, the cell gets damaged.

Cell count 
The 'S' rating of your battery shows the number of cells in the battery in series. For example, 1S implies 1 cell and so on. Most common batteries have 3S rating. Such batteries have a nominal voltage of 3*3.7 = 11.1V written on them. Nominal voltage is the resting voltage of a cell. At full charged it is  at 3*4.2= 12.6V and at fully discharged state it is at 3*3= 9V.

Capacity
Capacity of a battery is determined in terms of milli-ampere hours (mAh).  For example, a 1000 mAh battery would be completely discharged in 1 hour if 1A current is drawn from it continuously.

The same calculations are used while charging. If we charge a 1000 mAh battery at 1A, it would get charged in an hour and at 2A in half an hour. Sometimes the maximum charge rate is specified on the battery. Usually, safe charging is done at 1A. A 2000 mAh battery is charged at 2A, a 4500 mAh at 4.5A and so on....

Discharge rate
The 'C' rating of the battery shows the discharge rate of it. For example, a 1000 mAh battery has 30C rating on it, it means we can draw 30*1000=30,000 mAh or 30A of current safely from the battery continuously.

We know that if we draw 1A current the battery would last for 1 hour. Now that we are using 30A current, the battery would last for 60 minutes / 30 = 2 minutes.
The battery shown has 3 cells in series. It has a discharge rate of 50C which means we can draw a safe current of 250A from it. With 250A load, the battery lasts for 60* 5/250 = 1.2 minutes.  It has a 3C charge rate which means it can be charged at a maximum current of 15A. So, the lowest time it takes to get charged is 60*5/15 = 20 minutes.

While there are advantages there are a couple of disadvantages also. Because of high energy storage they burst or catch fire if not handled properly. LiPo batteries last for only about 300 cycles. To increase its life do not charge it over 4.1 V and do not discharge it less than 3.4 V!

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