4.7 LiPo Batteries

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LiPo Batteries

LiPo batteries are the main source of power for most drones on the market. They can contain very high amounts of energy and they need to be treated with a degree of caution.
The reason that LiPo batteries are heavily used within drones is because they have the following advantages over more common NiMH or NiCd batteries
Some of the advantage include;
– Much higher power to weight.
– Many sizes and shapes available.
– Very high discharge rates (able to provide large bursts of power)
However, they also have a few disadvantage;
– LiPo batteries can catch fire is damaged or charged incorrectly.
– Have to be charged, discharged and stored to specific requirements.
– Can be expensive.
– Can be difficult to post/ transport via air transport.
LiPo batteries contain electrolyte polymer and come in different sizes. The more cells the more energy and power they can hold.

Choosing a LiPo battery
Most manufactures now have specific batteries for their drones they are functionally the same however they may be inside a custom casing that will prevent you from using aftermarket batteries. Some manufactures however still use standard RC liPo batteries so if looking to buy extra batteries you will need to ensure that the numbers match up.

Capacity
Capacity is a measure of how much power the battery can hold, in most cases you will want a battery with the same capacity as the manufacture recommends as getting a lower/higher capacity will affect performance.
Many people think that by simply increasing the capacity of the battery you will improve your flight time. However, it’s a fine balance as a larger battery will weigh more and may lead to reduced flight times over a small battery.

Cell Count / voltage
This will tell you the voltage that the battery will provide to your drone, the voltage is calculated from the nominal voltage of a LiPo cell multiplies by the number of cells

The nominal voltage for a LiPo cell is 3.7v
e.g. 3.7v x 2 = 7.4

The working range for a LiPo battery is normally 3.0v – 4.2v

  • 3.0v is considered flat, running the battery down below this can cause failure.
  • 4.2v is considered fully charged.

Discharge rating
The C rating is a measure of fast the battery can provide “power” if the battery cannot meet the demands of the drone it will lead to damage and premature failure.
Most batteries will have two C ratings – continuous and burst.
Continuous rating is the amount of power the battery can provide continuously
Burst rating is normally a higher amount but it can only sustain that for a short burst.
For example, when a drone climbing at full throttle, it will draw more power than a drone flying at low speed.

Important information
Always read the manufactures instructions/recommendations when choosing a battery as failure to do so can lead to poor performance or worse a crash.

LiPo charging
Most new drones use intelligent batteries and they contain intelligent circuitry that recognizes it has a full charge and can start to discharge itself with a predetermined time frame set by the user.
Older LiPo batteries require to be discharged using a LiPo battery charger and this can be a longer process, as they need constant monitoring. The usual usage for a standard LiPo battery is around 400-500 full charges.

Important Information

LiPo Damage
Damaged LiPo batteries should be treated with great care and in any event that a LiPo battery has become faulty or is showing signs of damage (swelling or cracked) they should not be used and disposed of immediately. If a damaged battery is charged it can cause a damaged cell to result in a chemical reaction and in turn combust and catch fire.
The best way to deal with a LiPo fire is to allow it to carry out its burn and let the chemical reaction take place. The batteries create their own oxygen during the reaction, so containment is the best option.Travelling with LiPo batteries
When travelling with LiPo batteries steps must be made to ensure they are safe during transit. There are strict limits to what power battery you can take on an aircraft due to the risk of fire.
Most airlines will only let you travel with LiPo batteries that are below 100-watt hours. By design the standard DJI Inspire TB47 is 99.9 watt hours. Always check with your airline before you start your journey. You can find marked on the side of your LIPO what the power rating is.
Most airlines will demand that batteries are correctly stored when transported, this will usually involve having batteries in LIPO bags and most airlines will only allow the transportation of one of two batteries in the cabin as hand luggage.
Below is an example of some correctly stored batteries ready for a flight.

If charging an intelligent LiPo battery or an older “non –intelligent” version they always need to be monitored. This is because over charging can have very serious issues with the possibility of them catching fire. LiPos’ will burn very intensely and are very difficult to put out, hence it is recommended that all LiPo batteries are charged in a LiPo bag and kept in a LiPo bag for storage.


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