ESCs

4-in-1 ESC Guide: Amp Ratings, 20×20 vs 30×30, Voltage and Firmware

A 4-in-1 ESC is four speed controllers on one board under the flight controller. Pick it from the motors’ maximum current with margin — 45–65 A for a 5″ freestyle quad, 55–80 A for 7″ and 8S — then the voltage rating, the mounting size that matches your frame and FC, and a firmware that supports bidirectional DShot. This guide covers each decision and the small things (capacitor, pinout, direction) that burn boards.

Published 9 October 2026 · by the Fioparts team, Gurugram

What a 4-in-1 ESC is

A 4-in-1 ESC puts four electronic speed controllers on one board the size of the flight controller, with one battery input, one set of capacitors and a single ribbon cable to the FC. It replaced four separate ESCs on FPV quads a decade ago because it weighs less, wires faster and keeps the current path short. Single ESCs still make sense on DIY 450-class frames, fixed wings and anything above 8S — see single ESCs.

The amp rating

The headline number — 45 A, 55 A, 65 A — is the continuous current per motor the maker rates the board for. Burst figures (“55 A / 65 A burst”) describe a few seconds and are not the number to plan on. Choose from the motor’s maximum current with margin:

BuildMotor max current (each)4-in-1 rating
2–2.5″ whoop / toothpick, 1S–2S5–12 A12–20 A (usually on an AIO board)
3–3.5″, 4S–6S15–25 A35–45 A
5″ freestyle, 4S–6S30–40 A45–65 A
5″ racing, 6S40–50 A60–80 A
7″ long range, 6S30–40 A55–70 A
8–10″ cinelifter, 6S–8S40–60 A70–80 A, 3–8S rated

Heat kills ESCs, not the occasional spike. A 55 A board running 5″ freestyle motors at 35 A peaks lives for years; the same board on 8S 10″ props with 60 A motors cooks within a flight.

Voltage

Most boards are rated 2S–6S or 3–6S. If you fly 6S, the board must say so — the FETs and capacitors on a 4S-only board are not rated for 25 V. 3–8S boards (DAKEFPV BX 70 A, TBS Lucid 8S 60 A, iFlight Borg 60R, NewBeeDrone Hummingbird 305 80 A, Aocoda 2065) cover 7–8S cinelifter and long-range packs. Above 8S the 4-in-1 format stops; high-voltage single ESCs take over at 12S.

Mounting size

  • 30.5 × 30.5 mm (M3 holes) — the standard for 5″ and larger. Most 55–80 A boards; the roomiest heat-sinks. 30×30 stacks.
  • 20 × 20 mm (M2 or M3) — 3–5″ builds and lightweight 5″ frames. Modern 20×20 boards reach 55–65 A (Skystars KM55A, iFlight Blitz Mini E55, HGLRC Specter 60 A), so the size no longer caps you. 20×20 stacks.
  • 25.5 × 25.5 mm — whoop and toothpick AIO boards, where the ESC is on the FC itself.
  • 16 × 16 mm — rare; micro boards such as the Flywoo GOKU BS 20 A.

Some boards (NeutronRC Hold Mini) carry both 20×20 and 30.5×30.5 hole patterns.

Firmware: BLHeli_S, Bluejay, BLHeli_32, AM32

  • BLHeli_S — 8-bit, the budget standard for years. Fine for freestyle. Flash Bluejay on it (free, open source) to get bidirectional DShot, which Betaflight’s RPM filter needs; most new BLHeli_S boards ship with Bluejay already.
  • BLHeli_32 — 32-bit, closed source, licence fee per board. Mature, with current telemetry and variable PWM frequency; development has ended.
  • AM32 — 32-bit, open source, now the default on new boards from Skystars, SEQURE, TBS, NewBeeDrone, Zerodrag, Botlab and others. Same feature set as BLHeli_32 with active development and a free configurator.

For a new build in 2026 pick AM32 or BLHeli_32 if the budget allows, Bluejay-flashed BLHeli_S if not. All three run DShot300 / DShot600; set the protocol in Betaflight’s Motors tab and enable bidirectional DShot for the RPM filter. If a board beeps and the motors twitch, start with the beep codes guide.

Small things that matter

  • Capacitor. Solder a low-ESR electrolytic (35 V, 470–1000 µF for 6S) across the battery pads even if the board has one. It cleans the video feed and protects the FETs from voltage spikes on hard braking. Capacitors.
  • Current sensor. Most boards report amps to the FC over the ribbon cable; set the scale in Betaflight from the maker’s page so the OSD mAh counter is honest.
  • Ribbon cable pinout. Not standardised. An 8-pin cable from one brand may swap current and telemetry with another. Buy the FC and ESC as a stack, or check both pinouts before plugging in.
  • Motor direction. Reverse it in the ESC configurator or Betaflight; you never need to resolder phase wires on a 4-in-1.
  • Heat sink and airflow. 60 A+ boards on 7″ and 8S builds want the heat sink the maker ships and a frame that lets air reach it.

Stack or separate?

A FC + ESC stack from one maker gives you matched hole pattern, pinout, cable and firmware, and usually costs less than two boards. Buy a separate 4-in-1 ESC when you are replacing a burnt one, when you want a higher amp rating than the stack offers, or when the FC you want (H743, a GPS-heavy long-range board) is sold alone. Indian boards — Zerodrag Boost, Botlab BotStack — are under Made in India ESCs.

Sources & manuals