PwrTool 500

500A Smart Shunt for Home Assistant

We've recently started using this ESPHome component and thank the author for the work they've done.

24.04.10 - We've been accepted to do a crowdfunding campaign with Crowd Supply. More details coming soon - expect updated docs as we lock in final details.


A 500 amp smart shunt for DC power systems up to 60v* (50v for now). It is based on our FLIP-C3 mainboard and power center running ESPHome for seamless integration with Home Assistant out of the box.

An on board 45w NPN MOSFET can power fans, LED strips, or control external relays based on automations in Home Assistant. Also keep an eye on the ambient temp/humidity of your control box with the onboard sensor and catch potential issues with the on-die temp sensor of the analog-to-digital converter IC.

PwrTool 500 is fully open, this is your hardware and it is fully hackable. Extend it further with ESPHome, Tasmota or your own custom Arduino or ESP-IDF code. The on-board buck converter provides a total power budget of 10w for all of the activities. Make the PwrTool the brains of your power cabinet.


  • Hot or Cold Side use

    • Current beta hardware uses a switch - make sure it is in the correct position - no silkscreen

    • TODO:Polarity correction via H-bridge

  • Up to 60VDC* - works on up to 16s LiFePo4 systems

    • Bi-directional current and power up to 500A

    • Temp sensor on die placed near shunt fins

  • SHTC3 Temperature & Humidity Sensor for environmental monitoring

  • RGB LED & Red Status LED

  • CTRL- Connection for external control via NPN MOSFET


  • FLIP_C3 Mainboard

    • BLE 5.0 & Wifi b/g/n

    • 5v2A - up to 60v buck converter

    • ESP32-C3

      • Temp Range: -40 to 105 °C

      • Internal temp sensor

  • GPIO Components

    • Blue "Status" LED - GPIO 10

    • WS2812 NeoPixel - GPIO 8

    • User/Boot Switch - GPIO 9

    • Reset Switch - EN Pin

  • i2C Bus

    • SCL - GPIO 1

    • SDA - GPIO 0

    • Addresses

      • INA237 - 0x40

        • changeable with on-board DIP switch

      • SHTC3 - 0x70

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