Q: What is the Matek AP_Periph CAN-L4-BM Digital Power Monitor used for?

A: It is a high-precision digital power monitoring module designed for UAV and drone systems. It measures battery voltage and current data and transmits real-time power information through the CAN/DroneCAN protocol.

Q: What flight controllers are compatible with the CAN-L4-BM?

A: It is compatible with flight controllers that support the DroneCAN protocol, especially ArduPilot-based systems with AP_Periph support.

Q: What voltage range does the power monitor support?

A: It supports battery voltage input from 0V to 85V, making it suitable for various UAV power systems.

Q: How much current can the CAN-L4-BM measure?

A: It supports current measurement from 0A to 204.8A, with approximately 150A continuous current capability and up to 204.8A burst current.

Q: Does it require current calibration?

A: No. Thanks to the high-precision INA239 power monitoring IC and digital DroneCAN communication, it does not require traditional analog current calibration.

Q: What communication protocol does it use?

A: It uses the CAN bus with the DroneCAN protocol, providing stable and interference-resistant data transmission.

Q: What firmware does the Matek CAN-L4-BM support?

A: It runs ArduPilot AP_Periph firmware (MatekL431-BattMon) and can be updated through the DroneCAN GUI Tool.

Q: What power supply does the CAN-L4-BM require?

A: The module requires a 5V power supply input, with an operating voltage range of 4.5V–5.5V and approximately 10mA power consumption.

Q: Is the CAN-L4-BM suitable for FPV drones and large UAVs?

A: Yes. Its compact design and high current capability make it suitable for FPV drones, multirotors, and medium-to-large UAV power systems.

Q: What is the size and weight of the Matek CAN-L4-BM?

A: The board measures approximately 30×22×3mm and weighs only about 4g, making it easy to integrate into compact drone builds.

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Matek AP_Periph CAN-L4-BM Digital Power Monitor

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Top highlights

Built with TI INA239 and STM32L431 running ArduPilot AP_Periph firmware, it delivers accurate real-time voltage and current data over CAN without analog calibration.
Supports up to 0–85V input voltage and 0–204.8A current sensing (approx. 150A continuous), suitable for FPV, multirotor, and medium-to-large UAV power systems.
Uses DroneCAN protocol for direct communication with flight controllers, ensuring stable data transmission with strong anti-interference performance.
Features ultra-low resistance (approx. 200μΩ) current path design, with voltage accuracy of ±0.1% and current accuracy of ±2% for professional-grade telemetry.
Ultra-compact size (approx. 30×22×3mm) and only ~4g weight. Powered by 5V (4.5–5.5V range) with DFU firmware upgrade support for ArduPilot ecosystems.

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Tips

● The big pad on the bottom side is a dead pad. No any circuit network on it.

● Solder the positive wires as close as possible to both sides of the current sensing resistor.

● 2 ears for mounting can be cut off if you don’t need it.

● If the CAN wires are too long, bridge the “120R” jumper.

Matek CAN-L4-BM Buying Guide

The Matek CAN-L4-BM is a digital voltage and current monitor for ArduPilot aircraft using DroneCAN. It measures battery voltage up to 85V and current up to 204.8A, then sends the data digitally to the flight controller instead of relying on analog voltage and current-sense wires.

MEPSKING Expert Integration Assessment

From the MEPSKING expert integration perspective, the biggest advantage is the simpler calibration workflow. The INA239 monitoring circuit and AP_Periph firmware transmit digital readings through DroneCAN, so builders do not normally need to adjust the voltage multiplier and current scale required by many analog power modules.

This is particularly valuable on long-range multirotors, fixed-wing aircraft and professional UAVs where accurate battery information is used for telemetry and low-battery failsafes. The 200μΩ sensing path also keeps electrical loss low while supporting a published 150A continuous load.

The practical limitation is equally important: the CAN-L4-BM is a power monitor, not a flight-controller power supply. It requires a regulated 4.5–5.5V input and does not replace a suitable BEC or autopilot power source.

Do You Need a DroneCAN Power Monitor?

Application	Recommendation	Reason
ArduPilot Long-Range UAV	Recommended	Accurate battery telemetry and failsafe data
High-Current Multirotor or VTOL	Strongly Recommended	Measures up to 150A continuous and 204.8A burst
Basic Betaflight Freestyle Quad	Usually Unnecessary	ESC telemetry or an analog sensor is often sufficient
Flight Controller Without DroneCAN	Do Not Choose	A compatible CAN interface and firmware are required

Compatibility and Setup Checklist

● Confirm that the flight controller supports DroneCAN and ArduPilot AP_Periph. The Matek H743-Slim V4 Flight Controller provides a dedicated CAN connection and does not include its own current sensor.

● Supply the monitor with regulated 5V power. Do not connect battery voltage directly to its 5V input.

● Solder the positive power wires close to both sides of the current-sensing resistor. Use wiring and connectors rated for the aircraft's maximum current.

● For current readings above 90A, update from AP_Periph V1.7.0 or older firmware and configure BATT_MAX_AMPS = 204.8 and BATT_SHUNT = 0.0002.

● Enable the 120Ω termination jumper only when the module is positioned at the end of the CAN bus and termination is required.

Is the CAN-L4-BM Worth Buying?

Buy the Matek CAN-L4-BM when you need dependable digital battery telemetry for an ArduPilot long-range, VTOL or high-current UAV. Its main value is accurate DroneCAN reporting, minimal calibration work and support for high-voltage power systems. For a simple FPV quad without DroneCAN, it adds complexity without providing a meaningful advantage.

Specifications

● MCU: STM32L431xC, 256KB Flash

● INA239 85-V, 16-Bit, High-Precision Power monitor IC With SPI Interface

● Battery Voltage sense input: 0~85V

● Current Sense Range: 0~204.8A

● Load current on current sensing resistor: 150A(Continuous), 204.8A(Burst)

● Voltage accuracy: ± 0.1%

● Current accuracy: ± 2%

● Interface: CAN, DroneCAN Protocol, U-ART2, spare, DFU, -ST debug, SWCLK & SWDIO

● LED: Blue, (Fast blinking, Booting), Blue, (Slow blinking, working) Red, (3.3V indicator)

● Power supply for CAN-L4-BM board: 4.5~5.5V @5V pad/pin

● Power consumption: 10mA

● Operating Temperatures: -40~85 °C
Board Size: 30mm x 22mm x 3mm.

● Weight: 4g

● Firmware: ArduPilot AP_Periph MatekL431-BattMon

● Update: via DroneCAN GUI Tool

● Parameters: CAN_P1_DRIVER = 1 if attached to CAN bus1 port or CAN_P2_DRIVER = 1 if attached to CAN bus2 port, BATTx_MONITOR = 8 (DroneCAN-BatteryInfo)

Recommended Products

● Matek H743-Slim V4 Flight Controller

● Flywoo Explorer P30B 4S/6S 3000mAh Li-Ion Battery

● HOTA D6 Pro 1–6S AC/DC Dual-Channel Smart Charger

● TBS Smoke Stopper XT30/XT60 Safety Tester

● MEPS Fireproof LiPo Battery Safety Bag

Recommendation

More expert advice

FPV Drone Beginner’s Guide

How Much Does An FPV Drone Cost

How to Build a 5-Inch FPV Racing Drone

Reviews

A*******t
Verified

Accurate voltage and current readings right out of the box. DroneCAN integration was quick and required no calibration.

Specification：CAN L4 BM
A*******r
Verified

Excellent power monitor for ArduPilot builds. The readings stay consistent even during high current flights.

Specification：CAN L4 BM
D***********r
Verified

Handles high-current applications very well and provides clean telemetry for my Pixhawk setup.

Specification：CAN L4 BM
U*****h
Verified

Installation was straightforward with the JST-GH cable included. Firmware update was simple using DroneCAN GUI.

Specification：CAN L4 BM
T*******r
Verified

Great value for anyone building a DroneCAN system. Documentation made installation much easier.

Specification：CAN L4 BM
S*******r
Verified

Compact, lightweight, and very accurate. A great choice for larger UAVs using DroneCAN.

Specification：CAN L4 BM
R********r
Verified

Build quality is excellent and the CAN communication has been completely reliable so far.

Specification：CAN L4 BM
L**********V
Verified

Firmware configuration took a few minutes, but once completed everything worked flawlessly.

Specification：CAN L4 BM

FAQ Feel free to ask us any questions

Q: What is the Matek AP_Periph CAN-L4-BM Digital Power Monitor used for?: A: It is a high-precision digital power monitoring module designed for UAV and drone systems. It measures battery voltage and current data and transmits real-time power information through the CAN/DroneCAN protocol.
Q: What flight controllers are compatible with the CAN-L4-BM?: A: It is compatible with flight controllers that support the DroneCAN protocol, especially ArduPilot-based systems with AP_Periph support.
Q: What voltage range does the power monitor support?: A: It supports battery voltage input from 0V to 85V, making it suitable for various UAV power systems.
Q: How much current can the CAN-L4-BM measure?: A: It supports current measurement from 0A to 204.8A, with approximately 150A continuous current capability and up to 204.8A burst current.
Q: Does it require current calibration?: A: No. Thanks to the high-precision INA239 power monitoring IC and digital DroneCAN communication, it does not require traditional analog current calibration.