Ultimate LiPo Battery Guide for Drones

Welcome to this complete LiPo battery guide, covering everything from “What is a LiPo battery?” to “How to parallel charge a LiPo battery” and a lot more. If you are new to RC and using LiPo batteries, I recommend reading the whole page as there is some important safety information to make note of. There is a lot of info to take in and also quite a bit you may find yourself wanting to refer to down the line, make sure you bookmark it for later! While you are here, check out my reviews of the latest tech here.

The most important thing to remember is that LiPo batteries can be extremely dangerous (think fire and explosions!) if not used, charged or stored properly. Following this simple but reasonably comprehensive guide will help to reduce the chances of anything going wrong.

This Lipo Battery guide is split into sections, so you can easily find the information you need and skip over what you already know. Make sure you check out my pick of the best LiPo charger (the SKYRC iMAX B6AC V2 is a great starter charger) at the bottom of the page as well as my Top 5 tips to get the most from your LiPo Battery! Most of all, if you found this page useful, please share it so that others can benefit.

LiPo Battery Guide

What is a LiPo? LiPo Battery packs explained

LiPo battery safety (or avoiding a LiPo fire!)

LiPo Battery chargers & charging guide

LiPo Battery selection guide

How to dispose of a LiPo Battery (and when you need to)

The best LiPo charger?

LiPo Battery Guide

What is a LiPo? LiPo Battery packs explained

Lithium polymer batteries, more commonly known as LiPos, are rechargeable, pouch format batteries utilising lithium-ion technology. Rather than having a hard outer shell, they have a soft “polymer” shell. This makes them lightweight, but susceptible to damage. Within the shell are a positive and negative electrode, along with a separator; a liquid electrolyte is contained within the shell and provides the conductive medium. LiPo batteries are ideal for RC applications, where we benefit from the high energy density, high discharge rate and light weight when compared to other battery types. Because of their soft shell, LiPo batteries can be manufactured in a range of different shapes and sizes, to better fit into the gear you are powering.

LiPo Battery numbers explained

Voltage in LiPo batteries may be a little different to what you are used to. Each cell has a nominal voltage of 3.7V, but is operated between 3.0V and 4.2V. Discharging a LiPo below 3.0V per cell will cause damage to the pack and can be dangerous, as can charging to higher than 4.2V unless you have a specialised HV (high voltage) pack. More on charging later. Fundamentally, LiPo batteries are not discharged until empty as this causes damage. Normally an 80% rule is applied, meaning that you only ever drain 80% (or less) of the battery capacity and other than

S: LiPo batteries are made up of individual cells (some are simply a single cell), and battery packs will typically contain a number of cells in series. The nominal voltage of the pack is the voltage of each cell added together. This is where the cell count or “S” number for the pack comes in, since packs have a number of cells in Series. Voltages of some common LiPo battery sizes are given below as examples:

1S = 1 x 3.7V = 3.7V
2S = 2 x 3.7V = 7.4V
3S = 3 x 3.7V = 11.1V
4S = 4 x 3.7V = 14.8V
5S = 5 x 3.7V = 18.5V
6S = 6 x 3.7V = 22.2V

Drone motor RPM is a function of voltage (kV) and motors produce a number of RPM per volt. This means that (subject to your motor being able to handle it) by increasing the voltage, you can increase the power produced by your drone. In drone racing, 4S is the current standard, but clearly, moving to a 5S or 6S pack instead will give you a higher top RPM and more speed. 5S LiPo batteries are now becoming more popular and 6S LiPo batteries targeted at FPV drone racing are also beginning to surface.

Capacity is most commonly measured in milliamp hours (mAh) or amp hours (Ah) which is just 1000x larger i.e. 1,000 mAh = 1 Ah. The capacity defines the current that could be discharged for an hour, until the pack is completely empty (bad idea). You could also discharge at a higher rate for a shorter duration. For the majority of FPV drones, flight times are in the region of 3-6 minutes, so clearly we are putting large loads on our batteries!

In the most basic sense, the capacity of your LiPo is essentially the size of your fuel tank. Increasing your capacity will increase your flight time, to a point. Increasing the capacity also increases the physical size and weight, meaning you need more throttle just to stay in the air. There are many different sizes of batteries, but for FPV drone racing, the most common capacities are 1,300 mAh and 1,500 mAh. These provide a good blend of having sufficient capacity without being so large that manoeuvrability becomes an issue.

In larger drones, particularly stable aerial photography platforms, much larger capacities are used. These applications are not as dependent on being manoeuvrable and so can sacrifice this for longer flight times. Battery capacities of 5,000-10,000 mAh are not uncommon.

C: The instantaneous discharge rating of a battery, it allows you to calculate how quickly the LiPo can be safely discharged. Yes, I said calculate! The C rating does not instantly tell you the current you can pull from a battery. Instead, you multiply the capacity by the C rating, to get the current (Amps) that you can safely draw continuously. We’ll look at a standard LiPo as an example:

You have a 1,300 mAh (1.3 Ah) LiPo battery with a C rating of 50

1.3 x 50 = 65A

Related: Burst rating is often given along with the continuous C rating and is typically related to the current that can be drawn for a maximum of 10 seconds. A common example is a battery with a 50-100C rating. This means that for a maximum of 10 seconds, you can discharge this example 1,300 mAh battery at 100A. The burst rating comes into play when dealing with punch outs or rapid acceleration, when you will not be going to full throttle for any long duration.

Going above the C rating of your battery is bad for your battery health and will result in a lot of heat and puffing. This is why it is important to have a suitable LiPo battery for the application. For drone racing we are generally looking at packs with a capacity of 1,300 mAh or more and a C rating of 45 or greater as a minimum. Having used packs with a lower C rating than this myself, I can confirm that overloading a LiPo can very easily cause a pack to puff. Puffing is not a problem and you should not charge or use a battery if it is bloated.

Side note: some older LiPo packs were also configured with cells in Parallel, to provide an increased capacity by increasing the “P” of a pack. As technology has advanced, this is not frequently seen, so I will not go into more detail on this point.

How to read LiPo Battery specs or ratings

As we have just covered what all the numbers mean, you should now be able to read the specs from the sticker on your LiPo and understand what they mean. Just in case, I’ll run through a quick example:

You have a 1,500 mAh 4S 50-100C LiPo battery. This means you get:

Voltage: 12V completely empty, 14.8V nominal, 16.8V Full

Continuous current: 1.5 x 50 = 75A

Burst current: 1.5 x 100 = 150A

LiPo Battery connectors explained

There are a large number of different LiPo Battery connectors. For the main power connector, different types are available depending on the current that can be provided by the battery, but the rules are not always strictly followed.

The table below provides details of the most common connectors and their normal current ratings.

Connector Current Rating Burst Current
EC2 20 30
EC3 60 70
EC5 120 170+
XT-60 60 70
XT-90 90 120
Mini-Deans 15 20
Deans 60 75
JST 5 8
Tamiya 15 25
Traxxas 70 100
4mm Bullet 75 100
6.5mm Bullet 200 250+
8mm Bullet 300 350+
MPX 35 ?

The most popular connector currently used in FPV drone racing is the XT-60 connection. This provides a reasonable current rating, is easy to solder and provides good grip to plug/unplug. As you can see, the rating for the XT-60 is only 60A continuous. This may sound like a lot, but when you consider that there are now batteries capable of 95C continuous discharges being used for FPV drone racing, we may soon see a change in connector type.

In addition to the main power connector, a LiPo will normally have an additional/secondary connector known as the balance connector. This provides a connection to each individual cell in the pack and allows you to measure individual cell voltages. This is important as monitoring individual cells allows you to ensure all cells are evenly charged through use of a balance charger. More on charging later.

 

LiPo Battery selection guide

Choosing the right battery is important because as discussed above, the capacity, voltage and C rating will impact the weight and instantaneous discharge the battery is capable of. For a miniquad using standard 5″ props, the common battery sizes are 1,300mAh, 1,500mAh and 1,800mAh. Larger batteries are available with standard capacities ranging from 2,200mAh all the way up to 16,000mAh in a single pack, but these are typically for drones with larger props. These are designed for lower current draw and longer flight times and so aren’t well suited to miniquad use.

For drone racing, you need a combination of power and endurance, without adding too much weight (as this makes your drone sluggish). For quick acceleration you need high instantaneous current output, which means a higher C rated battery or a larger capacity, as these are capable of higher burst currents. Unfortunately they are also heavier. Generally, lighter is better when it comes to drones, but go too small with your battery’s capacity and although you will save some weight, you may not finish the race!

A good starting point is to select a 1,500mAh battery rated at around 50C. This provides a good balance of capacity, weight and instantaneous current and will be good for a range of races as well as freestyle. If you find yourself sagging the voltage because of long periods at high throttle, then a higher C rating or slightly increased capacity may help. If you need longer in the air because of a long race track, then an 1,800mAh or 2,200mAh battery of the same rating may be a good choice. Going above this when using 5″ props is not likely to increase real world flight time, because you will find yourself at a higher throttle position to account for the additional battery weight.

Which is the best LiPo battery for drone racing? Well for beginners and experienced pilot’s alike, great mid-range battery is the Infinity 1,500mAh 50C 4S. It meets the specification suggested above and comes in at a reasonable price. Yes there are better batteries, but if going for something more expensive, you start getting into diminishing returns. This may be OK for the top pro racers, but for flying around with your friends, why spend more than you have to.

 

LiPo Battery chargers and charging guide

This section is being produced and will be live soon!

 

LiPo battery safety (or avoiding a LiPo fire!)

This section is being produced and will be live soon!

 

How to dispose of a LiPo Battery (and when you need to)

This section is being produced and will be live soon!

 

The best LiPo charger?

This section is being produced and will be live soon!

 

Top 5 tips to get the most from your LiPo Battery

Flying drones isn’t cheap and a big part of the cost can be the batteries. If you follow the tips below, you will get the most from your LiPo batteries and avoid wasting money.

  1. Get the right battery for the job. One of the easiest ways to damage a LiPo is to over discharge (either capacity or current).
    • When selecting a battery, make sure that it will be able to comfortably meet the continuous discharge requirements of your drone and flying style.
    • Ensure the battery capacity is large enough for the flight times you want to achieve. If you fly for too long, your pack will be emptied too far and discharged below the low voltage level. Because of battery sag (voltage dropping under load) this is even more important if you are flying with high throttle punch outs.
  2. Don’t push your batteries beyond their limits.

 

 

Special thanks go to the following resources, which have been used as a source or for confirming validity of information:

https://en.wikipedia.org/wiki/Lithium_polymer_battery

https://www.reddit.com/r/Multicopter/wiki/power

http://www.rchelicopterfun.com/rc-lipo-batteries.html

https://www.maxamps.com/lipo-care.php

https://rogershobbycenter.com/lipoguide/

Related posts:

Leave a Reply

Your email address will not be published. Required fields are marked *