Voidbox Industries
Test Equipment
Power Management

PwrTool 500

A bipolar, bi-directional, 500A/60V power shunt and battery monitor for Home Assistant

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PwrTool 500 is the first in its class to offer both high- and low-side shunt functionality in one tool for monitoring up to 500 A on 12~48 V systems. Built upon our FLIP_C3 dev board, it features GPIO expandability and a robust 5 V/2 A buck converter alongside the 16-bit current sense ADC, a temperature/humidity sensor, and a 45W MOSFET for external control.

Seamlessly integrated with Home Assistant out of the box and customizable via ESPHome, it offers further versatility through Arduino or ESP-IDF compatible code, making it an ideal solution for diverse power monitoring needs.

Versatile Off-grid Applications

The PwrTool 500 and others in its class can be used in various locations of a DC system to monitor energy in and out. Placing it at the battery will allow you to monitor its condition and state of charge via coulomb counting. Separating loads and inputs with two shunts allows for a clearer picture of where power is going and coming from. A common example would be simply putting a PwrTool 500 on an inverter to monitor its usage compared to the other parts of the system which may be monitored elsewhere.

Most shunts of its type are "low-" or "cold-" side only, meaning the shunt itself is inserted in the ground path of your system. In some circumstances it may be difficult to intercept the ground path in a way that produces accurate results so we’ve built in an option to switch the PwrTool 500’s polarity.

Features & Specifications


6-60 VDC system voltage: Compatible with all lithium and lead-acid batteries
500 A peak / 300 A constant current shunt

45 W N-Channel MOSFET

FLIP_C3 Controller Board

Additional Features

Open Source

PwrTool 500 is open source and files are provided under the CC4.0-BY-SA license. Schematic, Board, & BOM were originally created in EasyEDA pro, and you can download the files for yourself here. 3D models of PwrTool 500 will be made available at a later date.

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About the Team

Voidbox Industries

Oakland, CA  ·   vdbx.io  ·   vdbxio  ·   vdbxio

Designer & manufacturer of open systems-integration hardware for off-grid applications using ESPHome and Home Assistant.

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