Battery and Flight Time

The most commonly used type of battery in the hobby field today is Lithium Polymer (LiPo), and this type was chosen for this project. The popularity of LiPo batteries is due to their large capacity, light weight, and excellent discharge capabilities. The following is general information about LiPo batteries:

  • Each cell of a LiPo battery has a nominal voltage of 3.6 volts and is fully discharged when each cell reaches 3.0 volts, and a battery usually contains 1 to 3 cells. (NB: discharging a LiPo battery below 3V/cell will make it un-chargeable.)
  • Current is rated in C’s which is the maximum discharge rate of a battery. For example, a 1C battery can handle a current that would take an hour to fully discharge and a 2C battery is capable of being discharge in ½ an hour.
  • The capacity of a battery is rated in milliamp-hours (mAh).

For this project, flight time will be analyzed to determine the appropriate battery. Flight time, which is directly proportional to battery capacity, can be found by dividing battery capacity by the amount of amps being drawn from the battery. Flight time is given in Equation 10 below.

The example calculation below shows that an 8A drain on a 2000mAh battery will maintain charge for 15 minutes.


The Turnigy 2730 Brushless Motor has a maximum amp rating of 10 amps.  Since there are a total of 4 motors, the total maximum drain of the battery will be 40 amps. Table 4 lists a variety of batteries with different capacities and their corresponding flight times at full and half discharge rates.

After researching the many different batteries available on the market, a Blue Lipo 1800 mAh 15C battery was chosen. This battery is approximately the same weight of the battery in the weight estimation performed earlier and has a capacity that will maintain flight for about 5.4 min at a 50% discharge rate.

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Comments
One Response to “Battery and Flight Time”
  1. Anonymous says:

    Awesome project!!!

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