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. 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

    • Selectable by twisting jumper position

    • Polarity and TVS protection

  • 6-60VDC - Compatible with any lithium or lead-acid system

    • Bi-directional current sensing up to 500A(300A contstant)

    • INA238 16-bit ADC with on-die temp facing shunt

  • 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 (10w) buck converter

    • ESP32-C3

      • Internal temp sensor

  • GPIO Components

    • Red "Status" LED - GPIO 10

    • WS2812 NeoPixel - GPIO 8

      • Level-shifted output on header as L8

    • User/Boot Switch - GPIO 9

    • Reset Switch - EN Pin

  • i2C Bus

    • SCL - GPIO 1

    • SDA - GPIO 0

    • Addresses

      • INA238 - 0x40

        • changeable with on-board DIP switch

      • SHTC3 - 0x70

Open Hardware

The PwrTool 500 is open source and files are provided under CC4.0-BY-SA

EasyEDA Pro

Schematic, Board, & BOM are originally created in EasyEDA pro. Also see FLIP_C3 files.

3D Models

coming soon - made in Onshape

Open Software


We are building out a modular set of configuration files for our FLIP_C3 platform and the products it powers. They are currently available on github here:

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