Skystars KO40 BLHeli_S 20×20 4-in-1 ESC

The Skystars KO40 is a compact 40A 4-in-1 ESC built on the 20x20mm mounting standard, tailored for 3-inch cinewhoops, 4-inch micro long-range platforms and lightweight 5-inch freestyle builds. Running reliable BLHeli_S firmware, it delivers smooth throttle resolution and handles the electrical demands of high-KV motors without taking up excess space in your flight stack.

Key features

• Delivers a sustained 40A continuous current per channel, handling aggressive throttle punches on lightweight builds.
• Supports a wide 3-6S LiPo input voltage range, making it versatile enough for 4S micros and modern 6S setups.
• Utilises an EFM8BB21 MCU to drive BLHeli_S, natively supporting fast DShot300 and DShot600 communication protocols.
• Features a high-density PCB layout with M3 mounting holes for secure installation in compact frames.

Specifications

• Input voltage: 3-6S LiPo
• Continuous current: 40A
• Burst current: 50A (10s)
• Firmware: BLHeli_S
• Processor: EFM8BB21
• Mounting: 20x20mm (M3 holes)
• Dimensions: 31 x 30 mm
• Weight: 5.4g

This ESC pairs perfectly with 150X to 200X class motors. When installing, ensure your flight controller shares a 20x20mm mounting pattern and verify the pinout on the included wiring harness matches your flight controller before powering up.