12S Battery Monitoring Board [Discontinued]

This product has been replaced by an updated version (click here!). This page is kept for reference purposes only.

Due to the potential hazards and liabilities associated with battery systems, this product is not currently offered for sale. We apologize for the inconvenience and will continue to evaluate producing battery monitoring systems in the future.

This hardware and software design files for this board (along with all products at four-forty) are open-source and will remain available as a service to customers and the DIY community. Please see our About page for details.

Please note! These designs are not rated or qualified to be safe, and relying on them is done at entirely your own risk. These designs may contain errors or bugs, and we cannot be held liable for the damages or consequences.  Please read our terms and conditions for more information and above all, use caution and common sense.

The 12S battery monitoring board acts as an smart interface between you and your rechargeable battery pack. Compatible with all Li-ion based chemistries and cell types, it allows you to measure voltages, sample temperatures, and perform bleed-balancing on cells – all over an isolated digital connection.

Features:

• Fully open-source design and firmware, with pre-loaded Arduino-compatible bootloader
• UART and I²C communication busses, capable of streaming data and on-the-fly parameter programming
• Two integrated 100k thermistor inputs per board for pack temperature monitoring
• Built-in 60mA cell bleed balancing capability, with programmable modes
• Built-in chip temperature monitoring, to prevent overheat during balancing
• Isolated operation up to 200V and expandable s-count up to 96S, permitting connection to low voltage systems*
• Watchdog timers to ensure reliable operation and balance shutdown during communication failure
• Detailed documentation and user guide

For more information, check out the documentation below:

• Battery monitoring basics guide (coming soon!)
• User guide (PDF)
• BMB interface guide (PDF)
• BMB pinout (PDF)
• Schematic (PDF)
• PCB Layout (PDF)
• Mechanical drawing (PDF)
• Eagle files (.sch+.brd)
• CAD Model (.step)
• Firmware repository (coming soon!)

*Isolation ratings represent the rated values of onboard isolation components. This product is not independently tested to meet isolation specifications, and may exceed the ratings of isolated components at higher s-counts.