Hi,
Lexie here!
Lithium-ion batteries have become an integral part of everyday life. They can be found in smartphones, cameras, laptops and all other conceivable electronic devices. A subspecies of the lithium-ion battery is the lithium-polymer battery, or Lipo for short. As FPV pilots, we use LiPo batteries for our drones. As soon as you buy your first drone, they become part of your daily life. But how much do you know about the safety and general maintenance of the batteries? In this blog post we will discuss a few topics:
1. Lipo lexicon/ terms worth knowing
3. Dangers when handling lipos
5. Rescue with deeply discharged LiPos (Attention: at your own risk!)
6. Storage
8. Disposal
Disclaimer: The information contained in this blog post is intended as general advice and is for educational purposes only. This blog post should not be considered "everything you need to know about LiPo batteries". You are responsible for your own battery safety!
Let's go!
In this section, we will briefly explain the most common abbreviations and their meanings. We will also go through the basic components of Lipos:
Lithium polymer batteries, better known as LiPo, have a high energy density, high discharge rate and low weight, making them a great candidate for RC applications. Once you know the basics about LiPo batteries, you will easily understand the specifications.
Battery voltage and number of cells (S)
LiPo batteries are made up of cells, each LiPo cell has a nominal voltage of 3.7 V (storage voltage - more on this later). If a higher voltage is required, these cells can be connected in series (S), creating a single battery. As specifying the battery voltage would be too complicated, we refer to the number of cells in each battery.
Connecting the cells does not mean more capacity, but more voltage, i.e. more power that can be delivered at the same time. To build a 4S 1000mAh battery, you could simply connect two 2S 1000mAh or one 3S 1000mAh to a 1S 1000mAh.
While we're at it...
Parallel connection (P)
We've already talked about connecting the cells in series (S), which doubles the voltage but maintains the endurance (capacity). If we now connect the cells in parallel, we double the endurance but keep the same voltage. The following picture shows a 4S2P battery in theory.
Capacity and size of the LiPo battery mAh
The capacity of a LiPo battery is measured in mAh (milli-ampere-hours). The mAh specification is an indication of how much current you can draw from the battery for one hour until it is empty.
C rating (discharge rate)
Lipo batteries for FPV drones are provided with a C rating. But what does that mean? LiPo manufacturers claim: "The more C - the faster" and this is partly true. The C rating is the maximum discharge rate. The more energy that can be delivered at the same time, the better. But note that many companies inflate their C-rating. This means that the actual value may well differ from what is stated. But back to the definition: If you know the C-rating and the capacity of a battery, you can theoretically calculate the safe maximum continuous discharge current of a LiPo battery.
Lipos have two connections:
The high-current connector with two wires, black and red. The full battery voltage is applied to this connector and it is also designed for the full current.
The balancer connector, which has one more wire than the battery has cells. One wire is usually insulated in a different color than the others, but there are also combinations of different colors. The individual voltages of all cells are connected to the balance connector; it must be connected to the charger when charging and a protective circuit can be connected to it in the Blaster
Balance connector
The balance cable or balance connector is used to check the voltages of the individual cells. It is also used to ensure that each cell of the battery is balanced and charged to the same value. This allows the battery to last longer and perform better. It is extremely important to charge your batteries with a balancing cable to ensure the longevity of your batteries.
The number of wires in an equalizer cable starts at 3 for a 2S LiPo and increases by 1 for each cell in the battery.
Choosing the optimal battery capacity for your needs
Here is a simple general guideline cheat sheet of battery capacity typically needed for different sizes of FPV drones.
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6 inch: 1500mAh - 2200mAh 5 inch: 1300mAh - 1800mAh 4 inch: 850mah - 130mmah 3 inch: 650mAh -1000mAh |
Does the flying style have an influence on the choice of battery?
Short answer: Yes
Long answer:
If you have a...
... Race pilot, you will probably want to use a battery with over 100C to ensure a high discharge rate. You can of course use a lighter battery. Around 1300/1400mAh is the gold standard among race pilots and has been tested on many tracks.
... If you're a freestyle pilot, you usually don't need anything really crazy with 120C unless you're going for really chaotic shots. You can also opt for a slightly heavier battery that will ensure the longest possible flight time together with the action camera. For this purpose, I would suggest 1400/1800mAh.
... If you are a long-distance pilot, you will probably be looking for capacity, not a specific C value. Why? Long range builds are meant to be as efficient as possible. You probably won't be doing a power loop over a mountain too often while flying around in a freestyle frenzy. You want some smoother flights with the most flight time possible. I would suggest either using something in the 6S2P or 6S 1400/2000mAh range.
... Cinematic pilot, you're probably looking for a smooth flight with the longest possible flight time. A battery in the range up to 100C with 1400/1800mAh should be perfect for you.
Which brand should I choose?
Please avoid "no-name" batteries and stick to a brand that you and other pilots are already familiar with! Ask around before you buy anything. In general, Tattu, SLS and Turnigy are well proven and popular with most pilots.
You can find a large selection of batteries from well-known manufacturers on FPV24.de under the Lipo batteries category.
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| Tattu battery LiPo battery 2S 450 mAh 30C XT30 Long | Tattu battery LiPo battery 450mAh 3S1P 75C XT30 | Tattu R-Line battery LiPo battery 500mAh 95C 1S1P long JST-PHR | GensAce battery LiPo battery1000mAh 11.1V 25C 3S1P with XT60 | Tattu Funfly series 1300mAh14.8V 100C 4S1P battery LiPo battery |
This is an extensive topic that you definitely need to be aware of! Your home, your health and literally your life depend on it.
Yes, batteries are great. They store energy and release it to power our FPV drones. But they are also dangerous. And it's not just that they're highly flammable, the big downside of Lipos is their susceptibility to damage, overcharging and temperature. Temperatures below 0 degrees and above 60 degrees can damage lipos to such an extent that the batteries pose a real danger. Lipos can catch fire. The fire produces a considerable amount of toxic gases and smoke. The worst thing here is the smoke, because it contains fluoride gas, which can damage the eyes, nose and respiratory tract. The only thing that helps here is the rapid use of sand or a fire extinguisher.
I know that there are always pilots who puncture batteries to see them burn or to smell the "LiPo smoke in the morning". BUT: don't do that! If a LiPo near you goes up in flames, it's best to get out of the danger zone as quickly as possible!
The perfect voltage
The perfect LiPo voltage is "the nominal voltage", which is 3.7 V per cell! While a charged LiPo usually has around 4.2V (you can HV - High Voltage) it can go up to 4.35, but we won't recommend that due to safety and... Readiness for the batteries to stay with you as long as possible. Well... the batteries should not drop below 3.2V as they will be damaged if they are discharged more! We generally advise you to land at 3.5V to ensure the longevity of the battery and its best health
How to charge LiPo's
Choose your charging location wisely. It is very important that you charge your batteries away from flammable objects and materials. If you want to charge them indoors, find a place near a window or door. That way you can literally throw it out if it catches fire.
Another thing I can recommend is charging it in a safe LiPo bag like the TORVOL Lipo Safe or an ammo box. If you want to see how lipo fires can be stopped by a good quality lipo safe bag, check out this amazing video from Torvol.
How fast should I charge?
It is recommended to charge LiPos at 1C for safety reasons. This means that you should charge a 1500mAh LiPo at 1.5A (1C x 1500mA). For a 900mA it should be 0.9A, and so on.
Close observation during the charging process
Never charge your batteries unattended. All the LiPo related fires I know of happened when the person was not in the room. And when they returned, it was too late. During the charging process, regularly check whether the battery is getting warm or swelling. If this is the case, you should stop the charging process immediately. Under normal conditions, a LiPo battery should never become warm during charging.
Parallel charging
I know it looks easy, fast and good. But my personal recommendation is: Please don't try this!
The types of charging
My recommendations: the best chargers
Disclaimer: If you attempt to rescue a battery using these instructions, do so at your own risk. If you are uncomfortable that your battery could catch fire, you should simply dispose of the battery.
When a LiPo battery is fully discharged, the cells oxidize. This is one of the reasons why they perform poorly. However, if you can recognize this quickly enough, you can usually save the battery without too much loss of performance. To save your battery, you will need
With these working materials, it is actually quite easy to restore a battery. Connect the main plug of your LiPo battery to your NiMH charger and start the charging process with the lowest possible current. This is normally 0.1 A. If your charger allows you to select the voltage, you should select a voltage that corresponds to the nominal voltage of your LiPo battery. After a minute or two, your battery should return to a voltage of around 3.3 volts per cell. To check this, simply read the total voltage of your battery and divide it by the number of cells. If the total voltage is around 3.3 volts per cell, you can connect the battery to your LiPo balance device and charge it with 0.5C. This will take longer than charging at 1C, but is safer. Once the equalization charge is complete, you should have a fully restored LiPo battery.
CAUTION! Do not leave a rechargeable battery unattended! If your battery starts to deform in any way during the charging process, you should abort the charging process.
You should always charge batteries in a fireproof place with good ventilation. If the battery cannot be balanced, you should consider discarding the battery as it can be very unpredictable during use and may catch fire.
When LiPo batteries are not used for a long time (e.g. during winter break or on vacation in a country where drones are not welcome), Lipos should be stored properly.even if LiPo's are only left unused for several days, they should not be stored in a charged state (4.2V per cell). How do you store LiPo's if you want to leave them unused for more than 3 days?
Transporting LiPo's from your home to the location is simple. You can just throw them in your backpack, right?
Well... unless you are unsure about possible damage or short circuits. I always use a secure LiPo bag to transport my Lipos. Whether in my Pitstop Pro or Explorer - wherever I go, the LiPos follow in their own bag. If you're interested in transporting your LiPo's (and gear) on an airplane - here's a separate blog post from us on the subject!
Disposal of LiPo batteries should be SAFE above all else. Never throw your LiPo batteries in the garbage can! You can imagine the temperatures that can arise in such a garbage can in summer and how quickly a LiPo can ignite. What if it is damaged by other waste or during transportation by the waste collection service?
The safest way to dispose of the batteries is to discharge them and throw them in one of the battery waste garbage cans. Such collection points can be found in most technology stores or DIY stores.
Incorrect handling of LiPo batteries can quickly lead to fires. So here is a quick cheat sheet with the most important safety rules:
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