When we go shopping for our much-awaited gadgets, we always check on the battery capacity and whether it has a great battery life or not. We’ve always considered certain factors when we are choosing Battery.
Right now, there are two main types of batteries available on the market. One is Li-ion batteries, which have long been a part of our smartphones and other portable devices. Lithium Polymer batteries, on the other hand, are now found in most current electronics and most of the new flagship models. In this blog, we are discussing how to Choose Lithium Polymer Battery for your RC Drone in detail.
What is a Lithium Polymer Battery?
A lithium polymer battery, or more precisely a lithium-ion polymer battery (abbreviated as LiPo, LIP, Li-poly, lithium-poly, and others), is a lithium-ion rechargeable battery using a polymer electrolyte rather than a liquid electrolyte. They’re also lightweight, have a low profile, and have a lower risk of electrolyte leakage. However, Li-Po batteries aren’t perfect because they’re more expensive to make and don’t have the same energy density or lifespan as lithium-ion batteries.
Because of their soft shells, lithium-polymer batteries are lighter and more flexible than conventional lithium-ion batteries, allowing them to be employed in mobile and other electronic devices, as well as remote control vehicles.
The lithium-polymer battery differs from other types of lithium-ion batteries in terms of the electrolyte it employs, which is a polymer in this case. A gel is used in modern lithium-polymer electrolytes, which allows for high conductivity at room temperature. A microporous separator is also used in the majority of these batteries. Instead of the more common porous separator used with ordinary types, the lithium polymer battery requires a microporous separator.
What are the cell configuration and battery voltage of the LIPO battery?
Rectangular cells are used to make a lithium polymer battery. The voltage of the battery can be increased by connecting the cells in series. The battery current will also be boosted by connecting the cells in parallel.
A Lithium polymer cell’s nominal voltage is 3.7V. A three-cell (3S) pack has an output voltage of 11.1V, while a four-cell (4S) pack has an output voltage of 14.8V. LIPO has a safe operating voltage range of 3V to 4.2V. Follow the instructions in the table below to configure the Lipo battery’s cells.
1. Cut off voltage:
The voltage at which a battery entirely drains is known as the cut-off voltage. Discharging the battery below the cutoff voltage of 3V may result in irreversible performance loss and perhaps battery damage. This means your voltage alarm should be set to 3.2 V or 3.3V.
2. Nominal Voltage:
The nominal voltage of the LIPO is 3.7V. It is the storage mode voltage of the battery.
3. Maximum/full charged voltage:
The voltage at which a battery reaches its maximum voltage is known as the maximum/full charge voltage. It is unsafe to charge the battery above 4.2V since it will eventually catch fire.
How does battery voltage effects the KV rating of the drone motor?
The voltage of the battery determines the speed of your motors. In comparison to lower-voltage batteries, higher-voltage batteries can turn motors faster.
The type of ESCs and motors you can utilize is determined by the voltage of your battery. The voltage required for proper operation or RPM will be shown by the motor and ESC combo. Brushless electric motor ratings perplex a lot of folks. A brushless motor’s KV rating refers to the motor’s velocity constant (v).
The motors also have a torque constant (Kt value) and a motor constant (Km value).
An example might be something like a 1000 Kv motor with a voltage range of 10 – 24 volts. That would mean this motor will turn at about 10,000 RPM @ 10 volts up to around 24,000 RPM @ 24 volts.
Means, Motor RPM= KV rating x applied voltage
The battery pack’s capacity refers to how much power/energy it can store. A LIPO’s capacity is measured in milliamperes (mAh) (milliamp hours). The term mAh refers to the amount of current that may be drawn from a battery for an hour before it runs out.
What is the C Rating (Discharge Rate) of a LIPO battery?
We can compute the Lipo battery’s safe, continuous,, and maximum discharge current by knowing the C rating and capacity.
Maximum continuous Amp Draw= Battery Capacity X Discharge Rate.
There are two C-ratings on some batteries: “continuous” and “burst.” The continuous current rating indicates how much current your battery can safely discharge over an extended length of time.
The burst rating indicates how much current your battery can discharge in a short amount of time ( it is around for 10 seconds).
From there, we can calculate the burst C rating requirement using this formula:
Burst C Rating = Max Current Draw / Capacity.
How to Choose Lithium polymer Battery for Your RC Drone?
Choosing the correct LIPO RC battery for your model involves many factors. You must first determine the voltage and amp requirements of the motor/prop combo you intend to use in your drone. Consider the following factors before purchasing a battery:
1. Find Out How Much Current Your Drone Can Draw
- Current draw from the drone motors:
To begin, select the motors based on thrust. The total current drawn by the motor can be calculated. For example, I’m planning to utilize this motor at full power, which requires 30A of current per motor.
Now, the total current= 30A *4= 120A.
- Current draw from Other Components:
There are other parts such as flight controllers, RC Receiver, LED, and FPV that uses the power from the same battery. It is little compared to the powerful motors so we can just add 1A to 2A to the total current draw. If you want to be a bit more precise.
2. Decide the Battery Size:
The size of the battery is a key factor in gaining greater flight experience. Always Choose a battery with a larger capacity to keep your drone running for longer. The capacity of a LIPO battery to give maximum flight time in the air is determined by the drone’s weight. You must select a battery with a specific size that will fit on your RC drone based on its physical dimensions.
3. Battery voltage
Battery voltage, also known as cell count, is an important factor to consider when making a purchase. Motors with a higher voltage rating will produce more power each revolution. The batteries with higher voltages ratings have more weight.
When choosing a battery voltage, make sure that your motors, ESC, and other electronics can handle the voltage. You must determine what is optimal for your present configuration based on the overall number of motors you are using.
4. Battery C rating
A LIPO’s Discharge rating is a significant characteristic. The Discharge C grade of your drone determines its overall performance. Professionally, we recommend using batteries with the highest C discharge rating.
Normally, a LIPO battery’s rapid discharge rate carries greater weight. It will undoubtedly add to the overall weight of your drone. In the end, your drone’s total flying time will be lowered.
Maximum Discharge Current = C-Rating * Capacity
The greater the C rating, the lower the capacity of a Lithium Polymer battery must be, and vice versa.
5. Battery Capacity
First of all, choose the battery with the biggest capacity to ensure a longer flight time. When choosing a replacement battery for your RC drone, always choose a size that corresponds to the device’s specifications. Its weight should not exceed the range of your drone’s lift capacity.
6. Battery Connectors
In a LiPo battery, there are two types of connectors. The primary connector is a power connector, while the balance connector is the other. There is only one primary lead in 1S batteries. Connectors come in a range of shapes and sizes, as well as current ratings and ease of usage.
Why do the LIPO batteries always come with female connectors.?
If two male pins of a battery are striking out, they may get bent and short together. The Female connector is used by the LIPO battery for safety reasons.
- Discharge /Power connector:
In this category, you’ll find a variety of battery connectors. The most common connector for a regular drone is the XT60 connector. Only 60A is rated for the XT60. When your drone requires a high current, you’ll need to use a separate connector.
- Balance connector:
The major purpose of the balance lead/connector is to guarantee that all cell voltages are equal. It allows you to keep track of each cell’s voltage. The LIPO voltage checker can be used to verify the voltage of each cell.
Hope this blog helps you to understand how to Choose Lithium Polymer Battery for your RC Drone. We, MATHA ELECTRONICS will come back with more informative blogs.