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Peterthegreat edited this page Nov 3, 2023 · 97 revisions

Replacing (or supplementing) your stock battery with a larger capacity battery can extend the flight time from 45 minutes to well over two hours with Li-Ion cells[1]. On the bottom of this page you can find some general information about batteries.

Table of Contents

Requirements

  • 9-12.6 volts (Stock is a 3-cell LiPo battery pack)
    • The motor is reported to drop in power around 9.5V: loosing height when turning, slow climbing.
    • The ESC sounds an alarm (using the motor) if voltage is below 9.1V before launch[2] and will cut off power at 9.0V with stock settings to protect the lipo battery.
    • This cutoff voltage can be lowered in parameters.cfg if you use a li-ion battery.
  • 16A power requirement during take-off[3]; when cruising the current draw should average out to ~3.6A[4]
    • the label on the Disco says 30A
  • balanced (the battery sits about in the middle, but too heavy or too much to a side makes your Disco unstable/quirky/inefficient)
    • people have been using batteries of up to 900 grams, but it will impact flight (and landing...)
  • dimensions: 3.4" wide, 1.7" long; the stock battery is 1.2" high but there's room for more.
    • you can cut out a bit of foam, but the servo wires run close to the battery
    • there's a bit of spare height available as-is
  • XT60 connector

Stock equipment

  • a 2700 mAh battery
    • '45 minutes runtime'
    • 25A [5]
    • 10C (source?)
    • 3.4 x 1.2 x 1.7 inches[6] (86mm * 30mm * 4.32mm)
    • 185g (6.5 ounches)
  • a balance charger
  • the SkyController 2 has a 7.4 V, 2.7 Ah battery[7]
    • charged with the same provided charger as the Disco's battery - but through a barrel plug.
    • the plug is probably a 3.4mm "Type H" (but perhaps a 3.5mm - input welcome: [email protected])
    • the barrel plug needs 12V, center positive [8]

Battery basics

  • 3000mAh is 3Ah, meaning the 'Amp hour' capacity: a 3Ah battery can provide a stream of 3 Ampere for 1 hour or 1 Ampere for 3 hours.
  • 1 C means "can discharge (supply it's full capacity to the drone) in one hour". So a 3Ah battery that is 10C, can give 3*10=30A of continuous power. A 2.5Ah battery that is 20C, could give 2.5*20=50A.
    • here is a difference in continuous C, peak C, and charging C.
  • The term 'LiPo pack' is commonly used for flat battery packs common in RC and thin laptops
    • The term 'LiIon" or "Li-Ion" is commonly used for round cells, like the ubiquitous '18650' that looks like a fat penlite - found in Teslas, vapers, older laptops.
  • Normal cells are charged to 4.2V
  • "LiHV" cells are carged higher, up to 4.5V. They are incompatible with the Parrot Disco.
  • 3s means three in series, so 3.7V*3=11.1V, or 3.8V*3=11.4V
  • 3s2p means three in series, but two in parallel, to double the power
  • (LiFePo4 can safely be ignored)
  • Because the battery pack consists of three cells, each cell has to be balanced while charging: hence, you need a balance charger.
  • "RC Airplane (How to...) - LiPo (Li-Po) Batteries Basics and Tips" https://www.youtube.com/watch?v=nRMwOMlA2M4&feature=youtu.be

How the Disco measures battery level

Many RC flight controllers with battery monitoring use a current sensor to measure how much energy is removed from the battery.

The Disco has no current sensor. Instead it monitors the battery voltage under load to figure out how much is left. This method has the advantage of the Disco not needing to know how large the battery is or how fully charged it was, to figure out how many percent capacity is left. The method has the disadvantage that it cannot know how much actual capacity is left, only how many percent.

When the motor runs on full power, the battery voltage temporarily drops. When the motor power is reduced, the battery voltage recovers. This is normal, and more pronounced in li-ion batteries than li-po. It means the battery voltage goes up and down all the time, depending on how much power you use.

To prevent the battery percentage display going up and down all the time, The Disco firmware only shows the lowest value it has measured. Any subsequent voltage recovery will not be shown. This can have unintuitive effects.

If you for example climb very high at the beginning of a flight, your battery level may drop rather quickly. Once you reach your altitude and start cruising, the battery level shown will stop falling and will remain on the lowest level you reached. It can be "stuck" there for quite some time.

This "battery level stuck" effect can also be seen with cold batteries. Cold batteries drop their voltage under load more than warm batteries, due to increased internal resistance. But batteries under load warm up, causing the battery voltage to in some cases actually rise with increased use! This too will result in the Disco user interface showing the battery level being stuck on the same value for longer than expected.

LiPo battery upgrades

Adding a bigger LiPo doesn't require changing your Disco settings, but you may need to cut out a bit of foam to fit the new battery.

Li-Ion battery packs

  • Many people fly battery packs made of 18650 Li-Ion cells. These cells provide higher energy per weight ratio than li-po batteries.
  • Li-Ion cells can not supply as high currents as Li-Po cells. Therefore you often use two or more cells in parallel (such as 3s2p).
  • 18650 cells exist that supply 30A. With such cells 3s1p will suffice. You do not gain much capacity compared to the stock li-po battery though.
  • A 18650 cell is shorter (65mm) than the battery compartment (87mm) and two are thinner (2*18=36mm) than the 43mm space, but three cells high (3*18mm) interferes with the xt60 connector to the chuck. This can be worked around.

Pre-built Li-Ion packs

(Updated 2023-04-22)

  • Upgrade Energy Parrot Disco Upgrade Battery is a 3s1p LG M50LT pack made in the USA.
  • Upgrade Energy Dark Lithium 3S 4200mah is a 3s1p Molicel P42A pack made in the USA. It is sold in their web shop but also available from GetFPV and Ebay.
  • Titan 3S 6000mAh is a 3s2p Murata US18650VTC6 pack made in the USA.
  • Marsen 10000mAh is a 3s3p pack made in Australia in a 5+4 configuration that is made specifically for the Parrot Disco. Unfortunately Marsen can't ship this pack outside Australia.
  • ElectronicaRC 3S2P 7000 mAh is made of Sanyo NCR18650GA cells. It is made in and shipped from Spain, and thus convenient for EU citizens. They build it with an XT90 connector as default, so remember to ask them to put on an XT60 instead.
  • ElectronicaRC 3S3P 10500 mAh is a 3s3p "bigger brother" to the above spain-made ElectronicaRC pack. Please note that such a heavy battery pack considerably alters the flight characteristics of a Parrot Disco.

DIY Li-Ion packs

You can absolutely make your own Li-Ion battery pack. You need to get a spot welder, they are available from ~$50 online. Such as this BIFRC one.

Recommended 18650 cells

  • As a general rule, higher storage capacity cells have lower discharge rate. You need at least 16A discharge rate for the pack, which in a 3s2p pack means minimum 8A per cell. A 3s3p pack can make do with 6A per cell.
  • For 1p packs (3 cells) these cells are recommended:
    • Sony US18650VTC6 3000mAh (2809 mAh @ 3A and 2483 mAh @ 20A)
  • For 2p and 3p packs (3/6 cells) these cells are recommended:
    • Sony US18650VTC6 3000mAh (2809 mAh @ 3A and 2483 mAh @ 20A)
    • Samsung INR18650-35E 3500mAh (3146 mAh @ 3A)
    • Sanyo NCR18650GA 3500mAh (3071 mAh @ 3A)
A note on cells: While many people have good experience with the low-discharge Sanyo and Samsung cells, they do not provide as linear a battery curve as the higher-discharge Sony cells do. What this means in practice is that, as the battery nears empty, big climbs will pull the battery percentage down quite fast with the Sanyo and Samsung cells while the Sony cells provide a more linear curve.

Recommended 21700 cells

  • 21700 cells suit the Disco well. The generally higher discharge rate of 21700 cells means it is possible to build light-weight 3s1p (3-cell) battery packs using these cells while still getting a good capacity boost compared to the stock battery.
  • For 1p packs (3 cells) these cells are recommended:
    • Molicel P42A 4200 mAh (3832 mAh @ 3A)
    • Samsung INR21700-40T (3647 mAh @ 3A)
    • Sony US21700VTC6A 4000mAh (3492 mAh @ 3A)
  • For 2p packs (6 cells) or larger, these cells are recommended:
    • LG 21700 M50 5000mAh (4630 mAh @ 3A)
    • Samsung INR21700-50E 5000mAh (4551 mAh @ 3A)

How does my pack fit in the Disco?

Depending on the size and disposition of your battery pack, you might have to carve a little in the foam on the side and/or behind the stock battery bay.

Here is a top view drawing of the stock battery bay showing the size of 18650 and 21700 li-ion cells in transverse and longitudinal configurations:

Here is a side view drawing comparing various battery pack configurations with the stock battery bay:

The approximate center of gravity is marked with a dashed line, but people have reported success even with a slightly tail heavy plane.

Software configuration for custom batteries

When using a li-ion battery pack, you don't have to change any parameters. But if you don't, the Disco will think you are still using a lipo and not use the whole capacity of your battery.

To use all of your capacity and to get proper % remaining reading with these packs, you need to change the voltage table the Disco uses to calculate battery state.

You need to configure the C.H.U.C.K flight computer by modifying /etc/parameters.conf. Make note of the hints on manipulating CHUCK firmware: settings get overwritten on upgrades!

Configuration parameters

Here are the parameters related to battery voltage you need to change. First is a list of voltage levels for various warnings and limits. They come from CrazyPilot's video. 

#/////////////////////////////////////////////////////////////
# BATTERY
BATTERY_FILTER_CO_HZ = 1.0
VBAT_MIN = 8.8
VBAT_LOW = 8.9
VBAT_SHUTDOWN = 8.3

#/////////////////////////////////////////////////////////////
# PREFLIGHT
PREFLIGHT_BATTERY_LOW_LEVEL = 10
#/////////////////////////////////////////////////////////////

# SAFETY
SAFETY_GROUND_PROXIMITY_CHECK_ENABLED = true
# Battery voltage below which a warning is emitted.
SAFETY_LOW_BATTERY_VOLTAGE = 9.0
# Battery voltage below which a critical failure is reported.
SAFETY_CRITICAL_BATTERY_VOLTAGE = 8.5
# Battery voltage above which a EMPTY BAT failure is cancelled
SAFETY_UNCRITICAL_BATTERY_VOLTAGE = 9.3
# Battery voltage below which a warning is emitted.
SAFETY_LOW_BATTERY_PERCENT = 9.6
#Battery voltage below which a critical alert is emitted.
SAFETY_CRITICAL_BATTERY_PERCENT = 0

In addition to the above voltage-specific parameters, you may want to try changing a few flight parameters to help the Disco handle the heavier battery. Some people experience roll instability with a bigger battery, and these changes makes the Disco more stable when turning: 

# Increase turn radius to 50m (default 30.0)
# This both reduces roll and slows down how fast the wind direction changes.
NAV_DEFAULT_RADIUS = 50.0

# Limit roll angle to 20 degrees (default 35.0)
NAV_DEFAULT_MAX_TURNRATE = 20.0

# If the above changes are not enough, you can try increasing cruise speed from 12 to 16 m/s.
# This increases lift and control authority at the cost of some endurance.
NAV_DEFAULT_AIRSPEED = 16.0

Default configuration / battery table for stock battery

See the default battery parameter values in the Parameters page.

Cell specific battery tables

You also need to change the battery percentage table to get an accurate reading. The table is slightly different for different battery packs, depending on the number and type of li-ion cells used.

Note! These tables are designed to let you use your battery to the fullest. There is very little "reserve" below 0% battery. Even before reaching 0%, your motor may produce less thrust and climb poorly due to the low voltage. Plan your flights accordingly.

These tables were generated using measurement data kindly donated by Henrik at https://lygte-info.dk.

Sanyo NCR18650GA

3s2p packs: (Use this for NCR 7000 mAh) 

BATTERY_PERCENTAGE_TABLE_LENGTH = 20
BATTERY_PERCENTAGE_TABLE_VOLTAGE = 8.5, 8.65, 8.79, 8.92, 9.16, 9.35, 9.51, 9.64, 9.74, 9.82, 9.99, 10.12, 10.7, 11.38, 11.53, 11.7, 11.83, 11.92, 12.0, 12.25
BATTERY_PERCENTAGE_TABLE_PERCENTAGE = 0, 1, 2, 3, 5, 7, 9, 11, 13, 15, 20, 25, 50, 75, 80, 85, 90, 95, 98, 100

3s3p packs: (Use this for NCR 10500 mAh or bigger) 

BATTERY_PERCENTAGE_TABLE_LENGTH = 20
BATTERY_PERCENTAGE_TABLE_VOLTAGE = 8.5, 8.66, 8.8, 8.94, 9.19, 9.41, 9.6, 9.75, 9.87, 9.97, 10.15, 10.27, 10.86, 11.52, 11.68, 11.86, 12.0, 12.1, 12.18, 12.38
BATTERY_PERCENTAGE_TABLE_PERCENTAGE = 0, 1, 2, 3, 5, 7, 9, 11, 13, 15, 20, 25, 50, 75, 80, 85, 90, 95, 98, 100

Samsung INR18650-35E

3s2p packs: 

BATTERY_PERCENTAGE_TABLE_LENGTH = 20
BATTERY_PERCENTAGE_TABLE_VOLTAGE = 8.5, 8.64, 8.77, 8.89, 9.1, 9.25, 9.38, 9.5, 9.61, 9.69, 9.86, 9.99, 10.61, 11.32, 11.52, 11.7, 11.8, 11.91, 12.02, 12.32
BATTERY_PERCENTAGE_TABLE_PERCENTAGE = 0, 1, 2, 3, 5, 7, 9, 11, 13, 15, 20, 25, 50, 75, 80, 85, 90, 95, 98, 100

3s3p packs: 

BATTERY_PERCENTAGE_TABLE_LENGTH = 20
BATTERY_PERCENTAGE_TABLE_VOLTAGE = 8.5, 8.67, 8.81, 8.94, 9.17, 9.34, 9.51, 9.67, 9.81, 9.92, 10.1, 10.25, 10.83, 11.51, 11.69, 11.88, 11.98, 12.07, 12.17, 12.41
BATTERY_PERCENTAGE_TABLE_PERCENTAGE = 0, 1, 2, 3, 5, 7, 9, 11, 13, 15, 20, 25, 50, 75, 80, 85, 90, 95, 98, 100

Sony US18650VTC6

3s1p packs: 

BATTERY_PERCENTAGE_TABLE_LENGTH = 20
BATTERY_PERCENTAGE_TABLE_VOLTAGE = 8.5, 8.63, 8.74, 8.84, 9.01, 9.16, 9.3, 9.44, 9.58, 9.7, 9.92, 10.08, 10.73, 11.38, 11.54, 11.66, 11.75, 11.83, 11.92, 12.22
BATTERY_PERCENTAGE_TABLE_PERCENTAGE = 0, 1, 2, 3, 5, 7, 9, 11, 13, 15, 20, 25, 50, 75, 80, 85, 90, 95, 98, 100

3s2p packs: 

BATTERY_PERCENTAGE_TABLE_LENGTH = 20
BATTERY_PERCENTAGE_TABLE_VOLTAGE = 8.5, 8.66, 8.79, 8.9, 9.09, 9.25, 9.39, 9.54, 9.68, 9.81, 10.06, 10.25, 10.94, 11.58, 11.76, 11.92, 12.0, 12.08, 12.18, 12.41
BATTERY_PERCENTAGE_TABLE_PERCENTAGE = 0, 1, 2, 3, 5, 7, 9, 11, 13, 15, 20, 25, 50, 75, 80, 85, 90, 95, 98, 100

3s3p packs: 

BATTERY_PERCENTAGE_TABLE_LENGTH = 20
BATTERY_PERCENTAGE_TABLE_VOLTAGE = 8.5, 8.68, 8.82, 8.94, 9.13, 9.29, 9.43, 9.58, 9.72, 9.86, 10.12, 10.33, 11.03, 11.66, 11.86, 12.03, 12.11, 12.18, 12.28, 12.47
BATTERY_PERCENTAGE_TABLE_PERCENTAGE = 0, 1, 2, 3, 5, 7, 9, 11, 13, 15, 20, 25, 50, 75, 80, 85, 90, 95, 98, 100

LG 18650 MJ1

3s2p packs: 

BATTERY_PERCENTAGE_TABLE_LENGTH = 20
BATTERY_PERCENTAGE_TABLE_VOLTAGE = 8.5, 8.66, 8.8, 8.92, 9.13, 9.31, 9.49, 9.64, 9.76, 9.86, 10.03, 10.15, 10.68, 11.42, 11.58, 11.73, 11.85, 11.95, 12.05, 12.28
BATTERY_PERCENTAGE_TABLE_PERCENTAGE = 0, 1, 2, 3, 5, 7, 9, 11, 13, 15, 20, 25, 50, 75, 80, 85, 90, 95, 98, 100

3s3p packs: 

BATTERY_PERCENTAGE_TABLE_LENGTH = 20
BATTERY_PERCENTAGE_TABLE_VOLTAGE = 8.5, 8.7, 8.87, 9.0, 9.21, 9.4, 9.59, 9.76, 9.9, 10.01, 10.21, 10.34, 10.88, 11.59, 11.75, 11.91, 12.03, 12.13, 12.22, 12.4
BATTERY_PERCENTAGE_TABLE_PERCENTAGE = 0, 1, 2, 3, 5, 7, 9, 11, 13, 15, 20, 25, 50, 75, 80, 85, 90, 95, 98, 100

Samsung INR21700-50E

3s2p packs: 

BATTERY_PERCENTAGE_TABLE_LENGTH = 20
BATTERY_PERCENTAGE_TABLE_VOLTAGE = 8.5, 8.65, 8.77, 8.89, 9.11, 9.31, 9.5, 9.65, 9.78, 9.88, 10.05, 10.18, 10.77, 11.45, 11.62, 11.81, 11.92, 11.99, 12.08, 12.31
BATTERY_PERCENTAGE_TABLE_PERCENTAGE = 0, 1, 2, 3, 5, 7, 9, 11, 13, 15, 20, 25, 50, 75, 80, 85, 90, 95, 98, 100

3s3p packs: 

BATTERY_PERCENTAGE_TABLE_LENGTH = 20
BATTERY_PERCENTAGE_TABLE_VOLTAGE = 8.5, 8.66, 8.8, 8.93, 9.15, 9.36, 9.56, 9.73, 9.87, 9.99, 10.17, 10.3, 10.91, 11.58, 11.76, 11.96, 12.06, 12.12, 12.2, 12.39
BATTERY_PERCENTAGE_TABLE_PERCENTAGE = 0, 1, 2, 3, 5, 7, 9, 11, 13, 15, 20, 25, 50, 75, 80, 85, 90, 95, 98, 100

Molicel INR21700-P42A

3s1p packs: 

BATTERY_PERCENTAGE_TABLE_LENGTH = 20
BATTERY_PERCENTAGE_TABLE_VOLTAGE = 8.5, 8.7, 8.87, 9.01, 9.26, 9.49, 9.67, 9.8, 9.9, 9.98, 10.12, 10.24, 10.84, 11.48, 11.65, 11.8, 11.87, 11.93, 12.01, 12.24
BATTERY_PERCENTAGE_TABLE_PERCENTAGE = 0, 1, 2, 3, 5, 7, 9, 11, 13, 15, 20, 25, 50, 75, 80, 85, 90, 95, 98, 100

3s2p packs: 

BATTERY_PERCENTAGE_TABLE_LENGTH = 20
BATTERY_PERCENTAGE_TABLE_VOLTAGE = 8.5, 8.72, 8.9, 9.05, 9.31, 9.55, 9.75, 9.9, 10.02, 10.11, 10.24, 10.37, 10.98, 11.63, 11.82, 11.99, 12.06, 12.11, 12.19, 12.38
BATTERY_PERCENTAGE_TABLE_PERCENTAGE = 0, 1, 2, 3, 5, 7, 9, 11, 13, 15, 20, 25, 50, 75, 80, 85, 90, 95, 98, 100

3s3p packs: 

BATTERY_PERCENTAGE_TABLE_LENGTH = 20
BATTERY_PERCENTAGE_TABLE_VOLTAGE = 8.5, 8.73, 8.91, 9.06, 9.32, 9.55, 9.76, 9.92, 10.05, 10.15, 10.27, 10.42, 11.04, 11.71, 11.89, 12.06, 12.13, 12.17, 12.26, 12.43
BATTERY_PERCENTAGE_TABLE_PERCENTAGE = 0, 1, 2, 3, 5, 7, 9, 11, 13, 15, 20, 25, 50, 75, 80, 85, 90, 95, 98, 100

General instructions for DIY battery packs:

Battery chargers

The battery charger included with the Parrot Disco is unfortunately rather poor at keeping the cells in balance, and it is recommended to replace it with a third party charger.

Chargers come in a wide range of complexity and price. You don't have to buy an expensive charger for your li-ion packs, alternatives can be had from $5 and up. LiPo and Li-Ion batteries are charged using the same algorithm, so all lipo chargers can also charge li-ion packs.

The simplest chargers are plug-and-play non-configurable chargers that have a fixed charge rate and only connect the balance connector. These work perfectly fine and are pretty foolproof. A downside is that they are a bit slow since the balance connector can only feed limited current. Examples:

The slightly more advanced chargers have a separate charge connector where you plug in the main battery lead, which allows them to charge faster. The balance connector is then only used to ensure cell balance. These chargers are typically configurable, both in terms of battery type and charging speed. Most of these chargers take DC input to be able to use them in the field, but some have AC input. Some examples:

  • SkyRC Imax B6 v2 (shown above) is an updated version of the workhorse Imax B6 that's been around since 2008 and copied by everyone. Max 6 cells and 6 amps. $35 for DC version, $50 for AC.
  • ISDT Q6 Lite is a modern compact charger with a big color display. Max 6S and 8A. DC only. $50.
  • ToolkitRC M6 is another popular compact charger with a color display and 6S/10A capacity. DC only. $25. Note: it is imprecise, you might want to calibrate it.
  • ISDT 608AC is one of the cheaper AC-capable modern chargers (i.e. that are not just iMAX B6 clones). Its' AC adapter is cleverly detachable so you get the best of both worlds. The display is smaller than on the Q6 though. 6S/10A. $50.
  • Imax B6 v1 (copy) is Hobbyking's (clearly labeled) clone of the SkyRC Imax B6 v1 charger. It sells for a mere $12 (or $25 with AC plug)
If you climb higher on the price ladder, you typically get capacity for more cells and higher amps. You can also get features such as the ability to charge multiple packs in parallell, connect the charger to your phone or computer, more advanced diagnostic functions, faster discharge etc.

Ballpen Trick

Use a ballpen and push its tip into the two connectors to widen them.

Third-party as well as the stock battery connector can squeeze CHUCK's XT60 power connectors over time and the connection might become lose. This can lead to sudden power-loss during a flight due to the vibration loosening the battery connector.

👉 It is advised to include this step as part of your pre-flight checks.

references

  1. ^ Louis Mcnair: 150 minute flight on YouTube
  2. ^ https://www.youtube.com/watch?v=YVNAgieJl9k
  3. ^ https://youtu.be/2i0zmSclT8g
  4. ^ calculated from capacity devided by flight time https://github.com/uavpal/disco-docs/issues/14
  5. ^ https://www.parrot.com/us/drones/parrot-disco-fpv
  6. ^ https://www.dronethusiast.com/parrot-disco-fpv-accessories/
  7. ^ Now behind a paywall: TechInsights: Deep Dive Teardown of the Parrot Disco FPV - Drone
  8. ^ source: Björn @ uavpal

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