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Chapter 05 · Components

From signal to power

The ESC gets from the flight controller how much power it wants from each motor and turns battery power into three-phase current, thousands of times a second.

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4-in-1 or individual

4-in-1

A single board for all four motors, mounted under the flight controller to form a stack. Tidy, light and easy to build. The usual choice today.

Individual

One ESC on each arm. If one burns out, you only replace that one, but the wiring is more complicated. These are rare now.

ESC diagram: the battery powers the 4-in-1 ESC, the flight controller sends it commands over DShot and gets power from it, and the ESC drives the four motors BatteryXT60 · 6S4-in-1 ESCpowerFlight controllerthe brainM1M2M3M4DShot5 Vthree-phase current
Thick line: power. Dotted line: commands from the flight controller (DShot). The ESC also powers the flight controller.

How to size it

  • Current: the continuous rating (not the burst rating) must cover what the motors draw, with some headroom. For a 5" on 6S, 45–60 A per motor is comfortable.
  • Voltage: it must handle the battery you’ll use (3–6S, or 8S on some models).
  • Mounting holes: the same as the flight controller (30.5 or 20 mm).
  • Connector: it should match the flight controller’s, or you’ll have to redo the cable.

ESC firmware

FirmwareChipNotes
BLHeli_S8-bitOld but widespread on budget ESCs. Can be upgraded to Bluejay.
Bluejay8-bitOpen source, the replacement for BLHeli_S. Supports bidirectional DShot for the RPM filter.
BLHeli_3232-bitVery popular until recently; development has stopped.
AM3232-bitOpen source and actively developed. The modern alternative to BLHeli_32.

You configure them with ESC Configurator, a web tool that connects through the flight controller. There you can change the motors’ spin direction, the PWM frequency (24 kHz tends to smooth out the flight), the startup tones and the temperature protection.

Recommended settings

With BLHeli_32 or AM32, most options are left at their defaults. These are the ones worth knowing:

SettingStarting valueWhy
PWM frequency48 kHz (24 kHz for racing)Less gyro noise and smoother flight. 24 kHz gives more torque but can vibrate.
Motor timing24° (16° for long range)More torque and fewer desyncs; 16° is more efficient.
Demag compensationDefault; High if you get desyncsStops the motor losing sync on sudden changes.
Rampup power20–30 % on 3" to 5"Limits current spikes.
Current protectionDisabledUnnecessary if the ESC is big enough for the drone.
Dead timeDon’t touch itA wrong value can overheat and burn out motors.

Protocols: how it talks to the flight controller

Old analogue

PWM, Oneshot and Multishot. The ESC had to be calibrated. Hardly used today.

DShot

Digital: no calibration needed and immune to noise. DShot300 and DShot600 are the usual ones.

Bidirectional DShot

The ESC reports back each motor’s rpm. Betaflight uses them for the RPM filter, which removes motor noise very precisely.

The low-ESR capacitor on the battery pads is not optional: it protects the ESC from the voltage spikes generated by sudden throttle changes.