The LiPo (Lithium Polymer) battery is a new type of battery used in drones and many other consumer electronics devices. This type of battery became very popular in the radio control industry over the last few years.
Presently, it is the most popular choice for anyone looking for long run times and high power. The LiPo battery has a lot of advantages. This article aims to educate new users to drone technology, with a focus on LiPo battery usage.
What Makes A Lipo Battery Different?
LiPo batteries provide power for all drone electronics and motors. The chemicals used in the battery are similar to those used in TV remote batteries. As its name says, LiPo battery is based on Lithium Polymer chemistry.
This chemical makeup allows for a very high energy density compared to other types of batteries. Higher energy density means the ability to hold more energy with the same weight. That is the reason why LiPo batteries are commonly used with R/C aircraft and drones.
Meaning of Lipo Numbers
Here is the explanation for all the numbers that define a LiPo battery. Knowing the meaning of these numbers will be of great help for you when you want to choose the right battery for your drone.
LiPo batteries consists of rectangular cells connected together to form the battery. A cell that can represent a battery in itself holds a nominal voltage of 3.6V. When there are more of the cells connected in series, the voltage can increase to 7.2V for a 2-cell battery, 11.1V for a 3-cell battery, and so on.
The battery capacity can also be increased by connecting more batteries in parallel. Numbers like 3S2P mean the battery has 3 cells (3S) connected in series. 2P means that there are 2 cell sets connected in parallel, giving a total number of 6 individual cells in the battery. The battery voltage is determined by the number of cells. Higher voltage provides 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.
The nominal voltage of each cell in LiPo battery is 3.6V. Regardless, when you use the battery the voltage will drop down. It is important not to let this minimum voltage drop below 3.0V. You must also assure that the maximum voltage for a Lipo cell is 4.2V.
When the voltage of any cell in LiPo battery is beyond this range, there is a high possibility that the chemicals become unstable. This can cause a fire. It is for this reason Lipo battery chargers are designed to ensure you only charge each cell to 4.2V.
Battery capacity means how long it can provide energy. It is measured in milliamp hours, (mAH). As this number increases, it increases the battery’s capacity as well. You will notice that your motors run for a longer time. The disadvantage is that the higher the capacity of a battery, the heavier the LiPo battery. Therefore, there is always a tradeoff between the battery capacity and weight for your aircraft.
4. Discharge Rate
It is very important that you pay attention to the discharge rate when buying a battery. Discharge rate, also known as the battery C rating (or continuous C rating) defines how fast you can extract the energy from your battery.
When your motor’s draw has more energy than your battery can provide, there is a possibility that you can cause damage to your battery. This will result in a drone crash. In order to calculate actual current in Amps, you simply have to multiply the capacity by the C value. So a 2200mAh battery, with a C rating of 25C, will have a continuous current output of 25 x 2.2 = 55A continuous current output.
In the past, we ran our cars or airplanes until the batteries died. We then placed the dead batteries, on shelves, at home; but not with LiPo batteries. Even more, LiPo batteries should not be stored at full charge. There's a lot to keep in mind.
1. Storage Capacity
If you want to use the full capacity of LiPo battery’s life, it must be stored at room temperature at 3.8V per cell. The majority of modern computerized chargers have a LiPo Storage function that will either charge the batteries up to that voltage, or discharge them down to that voltage, whichever is necessary. Proper LiPo Storage Voltage is 3.8V per cell.
We recommend that you put your LiPo batteries in storage mode after every run. This is not necessary, but it is good practice. If you do so every time, you will have no worries about whether or not you remembered to put it in storage.
There are many cases where LiPo batteries died because they were charged up with the intention to be used. The owners forgot to put them back to the storage voltage. Lithium-Polymer batteries can be damaged by sitting fully charged for as little as a week. This fact does not mean it will get damaged every time you leave it for over a week, it just means they can happen.
2. Storage Containers
It is recommended that you store a LiPo battery in a fireproof container. Most people tend to leave their LiPos in a LiPo bag. These bags are portable and protect your workshop from catching fire should the LiPo combust. The others use empty ammo boxes, fireproof safes, and ceramic flowerpots. No matter what kind of protection you use, it should be capable of preventing a fire from spreading.
The most common problem people have with LiPo batteries has to do with improper storage. When a LiPo battery sits for a long period, at proper storage voltage, it tends to discharge itself. If it drops below 3.0V per cell, the vast majority of LiPo chargers will not charge it. There are cases where batteries with this problem can be rehabilitated. However, they are often a lost cause.
Ultimately, if you do not properly care for your LiPo battery, it is more than certain that you will have to buy the new one.
LiPo Battery Disposal
We recommend that you check if the warranty has expired, before disposing of your LiPo battery. There are some companies, which provide one-year replacement warranties. You can take advantage this. However, most warranties will be voided if you perform the following steps before seeking a warranty replacement. Do note that keeping bad LiPo batteries can cause a fire.
1. Discharge the LiPo battery as far down as you safely can
There are a lot of ways to do this step. The majority of computerized LiPo chargers have a discharge feature in them. If you do not have a charger, with a discharge feature, you can run down the battery in your vehicle. Keep in mind that you risk a fire and potentially damaging your vehicle by doing this. So take care to have the necessary safety equipment around.
The other way is to build your own discharge rig with a taillight bulb and some wire. You will need to solder a male connector, of your choosing, to the tabs on a taillight bulb. Plug the battery in. However, remember, you must provide a fireproof container for this.
2. Place the LiPo in a salt water bath
That is right you read it well! One of the ways to get rid of an old, bad battery is to mix table salt into some warm (not hot) water. Then keep adding salt until it will no longer dissolve in the water. All the wires must be entirely submerged. One of the features of the salt water is its great conductivity, so it will essentially short out the battery, further discharging it. You will have to leave the battery in the salt-water bath for at least 24 hours.
3. Check the voltage of the LiPo
You ideally want the voltage of the battery to be 0.0V. Then you can move onto the next step. Otherwise, you should put it back in the salt-water bath for another 24 hours and continue doing this until the battery reaches 0.0V.
4. Dispose of the battery in the trash
It is a fact that LiPo batteries are not hazardous to the environment. They can be thrown in the garbage with no problem. Alternatively, if you do not feel like going through this process yourself, you can bring the battery to a disposal drop-off.
Tips to Extend Battery Life of Your Quadcopter
Depending on a drone model, flight time can range anywhere from 3 to 20 minutes or more. This depends on the model. Cheaper drones mostly have shorter flight times, but with the following steps, you will extend the life of your LiPo battery and enjoy more time flying your UAV.
1. Charge at the Right Time
Most people have a bad habit of recharging a battery days before they plan on using their new shiny toy. In that case, you may be inadvertently shortening the battery life. The best solution is to charge your battery just a few hours before you plan on using your quadcopter. A rechargeable battery will lose a percentage of its charge each day; that is if it is left off of the charger.
2. Follow the 40-80 Rule
It used to be recommended to charge your rechargeable batteries to full and then drain them completely before recharging. Today things are different: if you are using a lithium-ion battery to power your quadcopter; you may actually be shortening its life by draining the battery completely.The common lithium battery can be fully charged and drained between 300 to 500
The common lithium battery can be fully charged and drained between 300 to 500 times before it needs to be replaced. You can extend the overall life of your battery by filling it up halfway, or between 40% and 80%. As a general rule of thumb, you also want to avoid overcharging the batteries as well.
The temperature can also have an effect on the battery’s life. Charging your battery in a room that is 100 degrees F can actually reduce the battery’s capacity by 35%.
3. Fly in the Right Conditions
Flying in the right conditions is also important. If you are flying your device outdoors, you want to avoid flying during windy or rainy conditions. Wind will make it more difficult for your copter to turn, hover, and remain stable. This will drain more power from the battery than usual. Rain can have the same effect.
4. Experiment with Propeller Size
The size of your propellers will greatly impact the amount of power you use. If you are planning to integrate a camera in your device, you may want to consider a larger propeller. If you are not attaching a camera, a smaller propeller may be the better option. We recommend you start with the propeller size recommended by a manufacturer.
You should begin with the propeller size that the manufacturer recommends and experiment from there. Pay attention to how long a LiPo battery lasts to see which propeller size provides the longest flight time.
5. Choose a Battery with a Higher mAh
A majority of drones are equipped with mid-range batteries that do not offer the longest flight time possible. If you really want longer flight times, you will need to upgrade to a battery with a higher mAh. Look at your machine’s specifications for the maximum mAh your model can handle. Also, do not forget that a higher mAh will only be beneficial to a certain point.
The bigger battery means you will have a heavier drone. If the battery is too heavy, the added weight will only negate the extra power. Because of this, do not forget to consider the battery’s weight when choosing an upgrade.
6. Ditch the Camera
Yes, it is definitely great that you can attach a camera to a drone and record your flight. However, unless you are serious about aerial photography or videography, you may want to ditch the camera. The camera adds weight to the drone. The additional weight contributes to making flight more difficult. The copter will require more power to compensate for the added weight.