Battery Terminology

The purpose of this article is to provide complementary explanations on LiPo battery technologies as well as battery management. Refer to the dedicated battery manual for a detailed description of the battery handling guidelines.

 A Lipo battery has four main physical parameters: 

  1. Discharge capacity: remaining charge of the battery.
  2. Voltage: Defines the maximum rotation speed of the motors.
  3. Discharge rate: How much capacity the aircraft draws from battery per second.
  4. Internal resistance: Caused by physical and chemical imperfections wich cause power losses and heating. Directly linked to the temperature of the battery and its age


The most important indicators for the battery status are discharged capacity and voltage

When the voltage is too low, the motors will not be able to spin fast enough to sustain hovering. On Elios, this critical point is reached at 9.5V. In ELIOS 2 it is reached at 17V. But, as we can see on the figures presented below, the discharge capacity can not be easily linked to the battery voltage as this relation is dependent on the discharge rate, the temperature, the internal resistor, and its age. Furthermore, the capacity of the battery decreases with the number of cycles.



Elios Lipo voltage graphic2

Please note that the figure is just a qualitative illustration to show the effects of temperature and battery age on the relation between battery voltage and charge. The message is that the voltage will drop more quickly with an old/cold battery due to the higher internal resistance. 

The temperature has a direct effect on the internal resistance. The colder a battery gets, the higher its internal resistance gets and the lower the voltage will be for a given remaining charge.

The internal resistance also gradually increases throughout the lifetime of the battery due to chemical decay and acculumated damage from over-discharging. These effects can be minimized by always storing the batteries at 50% charge in a cool place, and by not completely draining the batteries in flight.

The ELIOS 2 smart batteries will automatically discharge to a suitable storage charge when not in use, but the ELIOS 1 packs must be manually discharged to avoid decay.


The first “low battery warning” is shown when the battery reaches 25% remaining capacity. The “battery critical warning” is shown when the battery reaches 10% remaining capacity. However, the drone will immediately show the battery critical warning if the voltage drops below 10.4V on Elios 1 and 17.5V on Elios 2.

It is thus important that the pilot remains aware of both the battery voltage and the battery capacity at all time. Those two values are displayed in Cockpit below as ''ROBOT BATT''. Please note that with ELIOS, if the battery voltage is below 12.4V when plugged in, Elios consider the battery as not fully charged and is not capable of measuring the remaining charge of the battery. Hence, Cockpit will display "??%" instead of the state of charge.

ROBOT_BATT.png         ROBOT_BATT.png


Also, the low battery warning and the battery critical warning are there to warn you that you have reached the limitation of the battery in normal operation. If it can be avoided, don't fly until the battery critical warning. The batteries might accumulate damage everytime they are operated beyond this point, and will show symptoms of old age after fewer cycles.






Documentation elios 2 Downloads

Here you can find the latest versions of the Elios 2 firmware. The latest versions are: Avionics v1.1.1    (FW_DRONE_V1.1.1_73ba5f1.BIN) Camera v072a  […]

Maintenance elios 2

This guide is meant to walk you through the update of the Flyability Elios 2 UAV firmware.

Cockpit Maintenance

This guide is meant to walk you through the update of Cockpit, Flyability's Android application.

Cockpit Documentation Downloads

Flyability Cockpit is the application used to pilot the Elios and Elios 2 systems. Its main use is to allow the pilot to view the live video feed from the […]

Troubleshooting elios 2

Basic diagnostic information is displayed on the four LED navigation lights of the ELIOS 2. A combination of blinking patterns and colors are used to […]

Practical Advice elios 2

Every Flyability drone comes with a complementary training, but for some users if is sufficient to go through a self-training process. The following […]

Troubleshooting elios 2

This article will guide you through the most common symptoms of malfunctions and how to fix it.

Maintenance elios


Documentation elios 2

Manuals Elios 2 Safety Instructions

Practical Advice elios elios 2

Here is an overview of all the measures we you can implement to preserve the integrity of your data. Whether it’s a matter of intellectual property or the […]

Practical Advice elios elios 2

You are allowed to travel by air with Flyability rones, but it is very important that you keep the following points in mind:

Practical Advice elios elios 2

During visual inspections, all areas of interest must be systematically visited and filmed. A well defined and executed flight plan will help you get the […]

Practical Advice elios elios 2

Gather information about the flight environment  Avoid unpleasant surprises by gathering as much information as possible about the flight environment […]

Troubleshooting elios elios 2

Calibration ensures that the control sticks have correct center point and range, the status LED on the GCS unit will blink red and a beeping sound will be […]

Maintenance elios

A pentagon can get unglued after a collision. This can easily be repaired following the instructions below.

Troubleshooting elios elios 2

We are only providing the Samsung T580 and T390N. Hence, please keep using this particular tablet with the Elios system, as we are developing the Elios […]

Troubleshooting elios elios 2

We use an internal Google account to set up the tablets, in order to use your own account, you’ll need to disconnect the Flyability account, then add […]

Troubleshooting elios elios 2


Troubleshooting elios elios 2

If Elios can’t reach its upright position after changing one or more propellers, make sure the propellers are put in the correct position (R mark […]

Maintenance elios

When the Batter Safety Clip is damaged or broken it must be replaced before the next flight. This is a simple procedure which you can perform yourself.