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Drone Battery – A Guide to Understanding LiPo Batteries

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Greetings! Distinguished readers! Thanks a lot for stopping by and taking time to go through our article on drone battery. Once you get your familiarized with LiPo batteries, we would invite you to have a look at other blog posts, articles and other stuff here. We will also endeavor to furnish some helpful links to other articles and user reviews that you might find interesting. However, you will be of great service to the drone community worldwide if you share this guide on drone battery with anyone who needs to know about LiPo batteries. More knowledge about these batteries will go a long way in ensuring that their favorite leisure time play becomes as safe as possible. Hey, isn’t this we all want? Agreed? We hope you have a nice read. In case of any queries, do not hesitate to get in contact with us! Ciao!

Writer’s Note

Bear in mind that this guide has taken years and years to be written down in the form that you can view on your computer screen. We have compiled this comprehensive tutorial to assist the drone enthusiasts both novices as well as veterans to enhance their knowledge about LiPo batteries and to ensure that their hobby does not result in serious damage to either them, their machine or even the bystanders in their surroundings. There has been plenty of conjecture and speculation among people regarding my purpose of writing about the risks associated with the usage of LiPo batteries. They believe that my information regarding charging, using and storing LiPo batteries is misleading at its best. I would like to articulate here that some of the criticism that I received from my opponents was rather scathing and lacked any appropriate justification.

I believe that most of the criticism at my writings was directed towards me by the very actors in the manufacturing industry who were of their view that their business was being disrupted since I professed certain practises while asking my readers to avoid others. However, in such scenarios, no such vicious attack by my opponents could force me to change a single word in my drone battery guide. I’m not someone who would bow his head and prostate before those who could go to any length just to prove that they alone were right in this whole world. Neither am I intimidated by large scale business enterprises who would bully their way into coercing others to do certain things the way they want. My sole aim is to develop a comprehensive guide that is brimming with useful and practical information with regard to drone battery. So, go through this article and make your hobby more safer than ever!

Introduction

LiPo is the acronym for Lithium Polymer batteries. These batteries were introduced in the market not so long ago and are being used in a multitudes of consumer electronic devices. Radio transmitter industry has taken a liking to these batteries and are being used widely across the board because of the long battery lifespan and greater generation of power.

A full spectrum of benefits can be obtained by bringing into use LiPo batteries. However, you have to determine whether the advantages are more in number as compared to the disadvantages in relation to your usage. With the passage of time, a vast majority of people have found out that their good features outnumber their bad ones. I am of the point of view that LiPo batteries are not at all fearsome as long as you abide by the rules developed with regard to their application and use them the way they should be.

I had to carry out extensive research in order to compile this exhaustive guide. I am not a chemical engineer and did my level best to ensure that all the information mentioned in this article is precise. I have discussed some technical terminologies but they are not scary. Having said that, do not consider that this guide will not contain any inaccurate information. This is an ever-evolving document and will keep on updating as knowledge about LiPo batteries becomes more and more advanced.

To start of things, let’s first take some time out to discuss the major differences among LiPo batteries and their Nickel Cadmium and Nickel-Metal Hydride compatriots.

LiPo Batteries Vs NiMH Batteries

In contrast to Nickel Cadmium (NiCd) and Nickel-Metal Hydride (NiMH) batteries, we get three main benefits from LiPo batteries:

  • They are very light in weight and can be produced in virtually any size or shape
  • They provide greater capacity as compared to their counterparts and hence generate more power
  • Owing to their higher discharge rates, they are preferred to other battery packs by drone enthusiasts

Having just gone through the advantages that one can get from LiPo batteries, it’s time to share some of the drawbacks:

  • As far as the battery lifespan is considered, LiPo batteries boast a much shorter lifespan in contrast to NiMH or NiCd batteries. They generally average between 300 and 400 cycles only
  • In case the batteries get punctured vent into the air, owing to their complex chemical configuration, they can easily catch fire
  • One needs to ensure that special care is taken when charging, discharging and storing LiPo batteries. The gear required to ensure their safe usage is quite costly.

Any idea what the numeric figures stand for?

Ratings system is what defines a batteries and renders it a separate individual entity. With the help of this ratings system, we are able to gauge the chemical composition and physical characteristics of the battery; thereby allowing us to figure out if the battery with us is suitable for our immediate need or not. LiPo battery contains three main ratings and knowledge of all three is essential for drone enthusiasts.

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Voltage/Cell Count

A Lithium Polymer cell boasts a nominal voltage of 3.7V. The battery shown in the figure provides 7.4V output which means that it has two cells of 3.7V each connected in series. We all know that in case of a series connection, voltage gets added. Hence, whenever you hear the term 2S battery pack in your surroundings do not get phased away. Now, you know that this terminology refers to 2 cells connected in series. This implies that a 2 cell (2S) battery pack will provide 7.4V while a 3 cell (3S) battery pack will furnish 11.1V and it goes on and on in the same way.

About Nominal Voltages

I was of the opinion that nominal voltages was a rather common topic, one that everyone ought to have knowledge of. However, I was amazed by the number of emails I got from the readers asking me to explain this terminology.

By nominal voltage, we mean the default, resting voltage provided by a battery pack. The folks in the drone battery industry prefer this terminology across the board to discuss and compare battery packs. Bear in mind that this is not the full charge voltage of the battery cell. A LiPo battery can be completely charged to as high a voltage as 4.2V per cell. However, the minimum safety limit for a LiPo battery charge is about 3.0V per cell. 3.7V is a moderate value that lies in the middle of the maximum and the minimum figures.

When LiPo batteries were initially introduced in the market, many of you would have come across terminologies such as “2S2P”. This means that the battery contains four cells out of which two have been connected in series while the remaining two have been connected in parallel. We are aware of the fact that capacitances get added together in case of a parallel connection. However, this jargon is a thing of the past now. These days, by virtue of advanced technology, the manufacturers are able to store much more energy in individual cells in contrast to the cells of the yesteryears. Nevertheless, it is always helpful to be aware of the terminologies of the yore. Since, you may come across them while doing some research or even if you find some battery packs of the old days.

It is the voltage provided by the battery pack that essentially determines how fast your drone is going to fly in the air. Voltage has a direct impact at the Rotation Per Minute of the electric motors. Brushless electric motors are rated by kV which means RPM per Volt. Hence, a motor with a rating of 3,500kV will rotate at 3,500RPM against every volt applied to it. In case of a 2S LiPo battery pack, the motor will rotate at 25,900RPM. In case of 3S battery pack, the motor will rotate at 38,850RPM. All this discussion means that the more voltage is applied to the motors, the faster are they going to spin and the more speed will be attained by your drone during its flight.

Capacity

By capacity of a battery pack, we mean the amount of power that can be stored in it. It may be regarded as the capacity or the size of the fuel tank. The capacity is measured in milliampere hours (mAh). This is basically corresponds to the load that can be applied to the battery so that it can be discharged completely in one hour. Remember that the drain of a motor system is generally measured in terms of Amperes (A). Let’s have a look at the conversion factor here:

1000mAh = 1 Amp Hour (1Ah)

As we mentioned earlier that the capacity of a battery resembles a fuel tank. So, in simple terms the capacity of a battery pack is actually the duration for which you can fly your drone before having to get your drone battery recharged. The higher the capacity, the longer will be your flight duration. Since aircrafts and helicopters are manufactured in a number of sizes and shapes, they do not boast a standard capacity. However, remote controlled cars and trucks boast 5,000mAh of capacity on average which also happens to be our most popular battery pack among consumers. Players in the battery manufacturing industry are producing batteries with even higher capacities. Traxxas has manufactured a battery pack that boasts a capacity as high as 12,000mAh. This is quite a big number but bear in mind that with higher capacities are associated higher risks and drawbacks.

Batteries with higher capacities tend to be bigger in size and heavier in weight. Moreover, it also has an impact on the heat produced in the motors and the speed control over a long period of time. If you do not check your motors from time to time, you can quite comfortably end up getting your motors burned down due to excessive heat being produced and insufficient time given to the motors to cool down. Furthermore, there are not many among us who would stop during their flights just to have a look at the motors if they need some cooling down. So, whenever you go for a battery that boasts a large capacity, keep these considerations in mind.

Discharge Rating (“C” Rating)

We have seen that voltage and capacity tend to directly have an impact on the speed and flight duration of your drone. Hence, they were rather simpler concepts much easier to comprehend. In contrast to these two, the discharge rating also known as the C rating is a much more complex point of moot. As a matter of fact, it is considered as one of those characteristics associated with LiPo batteries that has a number of speculations and conjecture linked to it.

By C rating, we mean the ability of a battery to get discharged safely without causing any damage to it. What really makes it a lot more hard to understand is that it is not merely an individual number. One needs to know about the capacity of a certain battery to determine the safe limit of the current drawn. Please note that the “C” in C rating actually represents the battery’s capacity. As soon as you get to know the capacity of the battery, you can simply put it in a formula and get to know the C rating. Taking the battery considered above for example, we can determine the maximum safe current drawn as

50C = 50 x Capacity (in Amps)

C Rating of our example battery = 50 x 5 = 250A

This is the optimum continuous load that can be applied to the battery. If you try to apply more load than this value, your drone battery will begin to get degraded at a rate much higher than it should. In some serious cases, your battery can also explode. Hence, our example battery can withstand a maximum sustained load of 250A.

Most of the batteries that are being produced these days come with two C ratings. The first one is the Continuous Rating which is being discussed. The other one is the Burst rating which is true for bursts of 10 seconds. Other than that, it is similar to the Continuous Rating. The burst rating can be considered significant when the drone is about to accelerate. However, as soon as it gathers a constant speed, the Continuous Rating comes into play. Remember that the Burst Rating is higher in number than the Continuous Rating. However, drone batteries are compared with each other on the basis of Continuous Rating and not Burst Rating.

The internet is flooded with a lot of garbage about what C rating is the best for your drone. Should you go for a higher value of C rating or a value that is able to cater your basic needs is better for you. The answers to these questions are not that easy and I would prefer to share my opinion with your rather than giving a final verdict. Before I set up a customer with a LiPo battery, I tend to determine that maximum current that is drawn by his/her machine. Here’s how it works:

Let us suppose that our customer is interested in purchasing a Slash VXL Remote Controlled Truck. According to the manufacturers, the maximum current draw is 65A and burst draw is 100A. With these figures in mind, I will be cognizant of the fact that a 2S 5000mAh 20C LiPo drone battery is the way to go. In fact, it is likely to produce more power than that required by the remote controlled device. Note that the battery has an optimum sustained discharging rate of 100A which is far more than that required to manage 65A that is drawn by the Velineon motor. Likewise, the burst rate of 150A is sufficient to cater 100A burst draw of the motor.

Having said that, remember that the ratings displayed on the motor are not sufficient to provide the complete landscape. The way the driver applies gears to the truck, the terrain on the which the truck is being driven, the diameter of the tires and the overall weight of the truck and other such things have an impact on the total current drawn on the battery. There is every possibility that the final current draw on the battery is higher than the optimum motor draw. It is always better to stay on the safe side of things and keep some cushion. Since, one cannot say for certain that such and such number won’t be crossed by the truck as it is being driven.

A 20C or 25C battery should work fine for most of the applications. However, I would recommend you to go for a 40C drone battery pack if you are flying a heavy drone, or are just limbering up to do some racing or are using a large motor for your 3D flying applications. Remember that it is not an easy decision to determine which battery pack would be the most suitable for your requirements. So, we would suggest you to go over to your nearest hobby shop and ask them to help you out in choosing the best drone battery pack that will be in accordance with your needs and requirements.

Equipping your LiPo: Proper Connectors

LiPo batteries store tremendous amount of power in them. Ideally, one would want as much power from the battery to get transmitted to the motors as possible. However, I have come across situations all too often when customers come to me with some impressive LiPo batteries attached to poor quality connectors. The problem that arises from bad quality connectors is that resistance is increased which in turn prevents power from being fully transmitted to the motors.

Traxxas Connectors

These high current connectors have been able to gain plenty of traction among users over the past few years. Remote controlled cars and trucks appear to be the most common devices that make use of these kind of connectors. However, they are becoming popular among drone enthusiasts as well who have begun to make a transition to Traxxas connectors. The ease with which one can set up these connectors is what has made them so much popular. Since the terminals are separate from the plastic casing, so it becomes a lot easier for even rookies to solder them. Moreover, since the plastic casing covers the terminals entirely, so one does not need to pursue heat shrink. Owing to their polarity protection, they cannot be plugged in the backward direction. Thanks to boasting the largest surface area in contrast to their counterparts, they are relatively easy to slide together or slide apart.

Dean Connectors

Regarded as the best choice when it comes to battery connectors, the Dean Connectors are quite comfortably the most favorite among savvy dronies and have been available on the market for a long long time. Having said that, if you are beginner, you might well face some difficulty while soldering them. The connectors have the ability to slide against each other seamlessly and boast an impressive design. Similar to all the modern battery connectors out there, they are polarity protected and are not far behind the Traxxas connectors when it comes to popularity. Traxxas connectors are mostly preferred by the enthusiasts of remote controlled cars and trucks while Dean connectors are fancied by the drone aficionados.

EC3 Connectors

These connectors burst onto the scene when Horizon Hobby made an attempt to replace the Tamiya Connector as its flag bearer. According to the folklore, Horizon Hobby contacted Deans to issue them the license for their connectors as they wanted to procure them in quite a large quantity. Their purpose was to get the connectors installed on the batteries at their factory. However, a deal could not be agreed between the two parties mainly because of the obstinance portrayed by Deans. Hence, Horizon Hobby had no way to go but to opt for EC3 and they got it licensed for themselves. Since then, EC3 connectors have been able to make a place for themselves in the market. They certainly are not an easy component to assemble but they have a niche of their own in the drone arena.

Tamiya Connectors

Owing to their remarkable market share, the connectors were named after Tamiya. They were initially called as Molex connectors and stayed as the most popular battery connectors among hobbyists for a number of years. To add to their fame, the Tamiya connectors came in almost all of the remote controlled vehicles manufactured by Tamiya. There are still some players in the remote controlled vehicles market such as Axial which continue to deploy them in their products. With regard to quality, they are very poor as they boast lots of resistance and you are more likely to end up getting them melted than anything else. If you come across a LiPo battery for one of your vehicles with a Tamiya connector, we would recommend you to cut them off and instead solder one of the above mentioned connectors in its place.

Venom Connectors

When viewed on paper, the concept about battery connectors put forth by Venom was quite impressive to say the least. I, myself, was particularly excited at the prospect of a battery connector that would interface with the four dominant connectors on the market. However, when I got them to see in person, I was quite disappointed as they were not able to live upto the hype created. I have to cut them off almost in all cases whenever one of my clients comes up with a battery with Vencom connectors attached to it. These connectors come with adapters that let them interface with Traxxas, Tamiya, EC3 and Deans connectors. As far as my experience is concerned, these adapters do a rather poor job. Since, they are an integral part of all the Venom batteries, so they have been included in our list.

Anderson Power Poles

In the initial days of radio control technology, these connectors were quite popular among the tech savvy. Most of our ingredients have generally been borrowed by other industries and same is the case with this connectors. They were designed originally by the ham radio industry for their 12V DC standard connector, they became quite popular in the radio control industry in no time at all. This plug is hermaphroditic, that is, it is neither male nor female. Since all of them are same so you won’t have to sweat over deciding which gender plug goes into the battery and which one into the throttle control. You won’t find them commonly in the remote controlled drones and vehicles but they are my personal favorites without any speck of doubt. They generally consume a large amount of space and so might not be really handy in a number of applications.

XT-60 Connectors

These connectors have been able to make a name for themselves over the past few years. They were originally developed by a Chinese manufacturer AMASS and then HobbyKing either got them purchased or retrieved the license for the patent. Let’s not waste our time discussing their story of origina. They are gaining popularity since they are installed in almost all the batteries that come out of China. There aren’t a lot of local batteries that make use of these connectors. I quite fancy the connector since it is a lot easier to solder. It is rather small in size. They might not be my favorites but certainly do a good enough job. We could land up with even worse connectors than these.

These are the most commonly used connectors in the R/C world. Other connectors have also been introduced in the market but have not been able to gain traction among users. I would suggest you not to go for the Tamiya and Venom connectors stated above. Other than these, you can go for any of the aforementioned connectors. If you are interested in the ParkZone Sport Cub BNF Airplane aircrafts, then EC3 connectors will be the way to since these planes come with these plugs. Traxxas connectors are the preferred choice if you are driving a Traxxas vehicle. These plugs generally have more or less the same features. Try to go for the plugs that your vehicles come with in default configuration. Do not try to make things more complex than they have to be.

Let’s discuss balancing plugs. Here are the main ones:

JST-XH Plug

When it comes to balance plugs, probably these are the best. Almost all the major players such as Traxxas, Venom, E-Flite and Duratrax. These plugs are preferred by the low cost battery manufacturers in China. It may not be as sophisticated as the Thunder Power Plug mentioned below, but they can be found quite commonly. Not a lot of manufacturers avoid using these plugs for the balance wire. Take care to unplug them by holding onto the plastic casing. If you try to pull out from the wires, you will almost certainly end up pulling the wires out from the housing and eventually short circuiting the battery.

Thunder Power (TP) Plugs

I have been disappointed by the Thunder Power’s preference for balance plugs for a number of years. The company is well known for producing some of the most sophisticated and expensive battery packs in the industry but their connectors are not compatible with most of the chargers on the market. Most of the chargers require an adapter from JST-XH to TP connector. However, they boast a remarkable design while the little clip on top of the plug makes it easier for the user to unplug them without causing any damage to the plugs. Since they are only installed on Thunder Power and E-Flite battery packs, so, I won’t recommend them to you overwhelmingly. But it certainly takes an edge over JST-XH.

If you go for the above mentioned models, you will certainly not end up losing your investment. You can check out our blog to get access to more reviews on the latest products on the market. Lastly Don’t forget to read our detailed article on LiPo Batteries – How to choose the best battery for your drone as below.

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LiPo Batteries - How to choose the best battery for your drone

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