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All you need to know about Drone Batteries

19 January, 2024

All you need to know about Drone Batteries

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In the wild world of drones you can find a huge variety of batteries. In this article we examine the basics you need to be aware of when buying a drone battery.

Drone batteries

All things that fly do so by using a portable form of energy. Traditional airplanes or helicopters or hot air balloons rely on fuel-powered engines, but drones rely on batteries. Drone batteries are compact and lightweight. This is absolutely necessary in drones, because it directly affects their range and duration of operation. With drones being used in applications such as aerial photography, surveillance, or even search and rescue missions, the specifications of a drone battery are critical. Drones use electric motors for propulsion and control. The drone battery supplies the required electrical energy to these motors and allows for precise and agile movements during flight. As you would expect, the capacity and efficiency of a drone battery will have a direct impact on the flight time of the drone, something which can make a huge difference on applications like aerial surveys, monitoring large areas, or conducting inspections.

The types of drone batteries

As with all other batteries, drone batteries come in different types, or to be more accurate, different chemistries. The most common ones are Lithium Polymer (LiPo) and Lithium-ion (Li-ion). The choice between the two chemistries depends on the specific requirements and use case of where the drone will be used. Let’s see a bit more about each one:

Lithium Polymer (LiPo) Drone Batteries

LiPo batteries generally have a higher energy density compared to Li-ion batteries, which means they can provide more power in a smaller and lighter package. This is really useful when the drone being used needs to be as small as possible. They also deliver high discharge rates, which makes them suitable for applications that require quick bursts of power, such as drone racing or acrobatics. And all this can come in any shape and size, which can help with the aerodynamics of the drone itself.

A Lithium Polymer (LiPo) Drone Battery

A Lithium Polymer (LiPo) Drone Battery

The problem with LiPo drone batteries is that they are inherently more prone to thermal runaway, which means there is a higher risk of catching fire if mistreated. This is important for new “pilots”, who are always more prone to having their drone crash, increasing the chances of a battery puncture. Furthermore, LiPo batteries may have a shorter lifespan compared to Li-ion batteries, especially if subjected to high discharge rates.

Lithium-ion (Li-ion) Drone Batteries

Li-ion batteries are generally considered safer and less prone to thermal runaway compared to LiPo batteries, so they are a good choice for novice pilots. They offer a longer lifespan, which means that (with the correct charger) you can get a higher number of charge-discharge cycles from them.

A Lithium-ion (Li-ion) Drone Battery

A Lithium-ion (Li-ion) Drone Battery

Unfortunately, Li-ion batteries typically have a lower energy density than LiPo batteries, which may result in a heavier and bulkier battery for the same energy capacity. If the drone is not big enough, this will definitely affect the flight time/range. Also, it is generally not recommended to use them in high-performance drone applications as they are not that good in providing quick bursts of power.

What drone batteries should I choose?

Let’s consider your needs:

  • If your drone requires high energy density for longer flight times or high discharge rates for dynamic manoeuvres, LiPo batteries may be more suitable. If safety and a longer lifespan are higher priorities, Li-ion batteries might be a better choice.
  • If safety is your primary concern, especially for beginner drone pilots or applications where mishandling is more likely, Li-ion batteries may be a safer option.
  • If minimizing weight and achieving a compact design are critical factors, LiPo batteries might be preferable despite the safety considerations.
  • Consider the cost and availability of both types of batteries. LiPo batteries are more common and often more affordable, while Li-ion batteries might be pricier but offer certain advantages as mentioned above.
  • A good rule of thumb is to check the battery that came with your drone. Be aware though that drone manufacturers may choose battery chemistries depending on how they want their drone to perform, but these decisions are also based on production costs. It’s not a bad idea to consult other owners of the same drone model you have online to see if they have experimented with a different chemistry and what the results were.

How does a drone battery’s capacity affect its flight time?

Battery capacity is the amount of electrical charge a battery can store and deliver over time. It is typically measured in milliampere-hours (mAh) for small batteries like those used in drones. The higher the capacity, the more energy the battery can store, which means the longer the flight time will be. For example, if a drone has a 4000mAh battery, and it consumes 400mAh of power per minute, it can theoretically fly for approximately 10 minutes (4000mAh / 400mAh per minute). This may sound too little, but it durations up to 15 minutes tops are actually the norm for small drones costing up to £500 / $500. Things of course change when we are talking about bigger ones used by professional filming crews, security services or the military. In these cases, the time could go as high as 3-4 hours for filming these amazing BBC documentary shots, or up to 32 hours for a military drone like the Global Hawk RQ-4 manufactured by Northrop Grumman for the US Air Force, which will set you back around $132 million. Just a side note here, this article concentrates in battery powered drones only. We mention this as there are also solar powered drones, such as the experimental Airbus Zephyr S designed in collaboration with the US military and built at a facility in Farnborough, England. In its latest test the Zephyr flew above the Sonoran Desert at stratosphere level (height of 20 km or 66,000 ft or 12 miles) for 42 days!

Northrop Grumman RQ-4 Global Hawk Drone

Northrop Grumman RQ-4 Global Hawk Drone

Ok, let’s land back to normal drones now. The battery capacity is only one of the factors that affects the flight time though. Other factors that come into play are:

  • The drone’s weight. The lighter it is, the longer it will fly for.
  • The efficiency of the motors. Better designs will allow more time.
  • Aerodynamics. Pretty self-explanatory, but to give the general idea, a brick isn’t as aerodynamic as an arrow.
  • Flight conditions. Does the drone need to fly against the wind? The drone will have to work harder. Is it too cold? The battery will be depleted faster. Is it raining? Unless you have a very well built drone, better not fly.
  • The abilities of the pilot. Experienced pilots will know how to take advantage of aerodynamics and weather to optimise the flight time, even in adverse weather conditions. After all, search and rescue missions using drones aren’t always done in sunshine. Also, smooth flights consume less energy than erratic ones with sudden movement or changes of direction.

Drone batteries charging, discharging and maintenance recommendations

As with any and all types of batteries, always use the charger recommended by the drone or battery manufacturer. Using an incompatible charger can lead to overcharging or undercharging, affecting the battery’s lifespan. Make sure you charge your drone batteries in a safe and well-ventilated area and never charge batteries with different capacities at the same time. Also, do not leave batteries connected to the charger for an extended period after they reach a full charge.

If you plan to store your drone for an extended period, ensure the batteries are charged to around 50% and not completely full or completely empty and store them in a cool and dry environment. When you are ready to fly your drone again, give them a nice charge all the way to 100%.

What to do with a drone battery after a crash

Before anything else, here’s a warning: never use a drone battery after a crash!

Drone battery after a crash

Drone battery after a crash

We have already mentioned how sensitive Li-ion batteries are and how well you need to look after them in our article Why do Li-ion batteries explode or catch fire? but there are some steps you need to take after a drone crash:

  • If the drone is still powered on or connected to the battery, disconnect it immediately to prevent any potential issues or further damage.
  • If the battery or surrounding components are warm or hot, allow them to cool down before handling. Overheating can be a sign of internal damage, and attempting to use a hot battery can pose safety risks.
  • If the battery is cool (or after it cools down), carefully inspect it for any signs of damage, such as punctures, swelling, visible deformities or leaking fluids. If you notice any leaks, handle the battery with extreme caution as the fluids may be corrosive or flammable. If you notice any punctures, handle the battery and drone with extreme care and place them away from any flammable materials or items. The best approach is to bury the drone and battery in a bucket of sand, but since you may not have one with you (and why would you?) just keep the distance from anything else that may be flammable. That includes houses, vehicles, liquids etc.
  • If you cannot see any punctures or damage, you are still not in the clear. Remove the battery from the drone to prevent any potential electrical issues and allow for a more thorough inspection. Place the battery in a fireproof container or on a non-flammable surface away from flammable materials and if you have any concerns about the battery’s stability, consider placing it in a safe location outdoors.
  • After ensuring there is no visible damage, charge the battery to its full capacity and then discharge it to ensure it holds a charge properly. Monitor the battery during this process for any signs of abnormal behavior, such as overheating or sudden voltage drops. It’s also a good idea to monitor the battery for signs of swelling or changes in shape. Swelling can indicate internal damage and is a clear sign that the battery should be retired and replaced.
  • Never use a damaged battery if it exhibits any signs of damage, malfunction or abnormal behaviour. Follow proper disposal procedures according to your local laws and never dispose of batteries in regular household waste.

By following the guidance above, your batteries will be in tip-top condition, safe to use, and will provide the maximum flying time to your drone!