4s BMS 120a LifePo4 with 24″ 8ga Wires

(2 customer reviews)


  • Comes with 24 inch long 8ga wires soldered to the board as shown.
  • BMS For 4 cell, 12v volt Lithium-iron-phosphate DIY batteries
  • 120 amp continuous charge or discharge current
  • Low Temperature Charging cutoff at -1c
  • Fully programmable with IOS app, Android app, or Desktop app
  • User Manual: Click to Download the PDF user manual

End-of-Life Notice

The 4 cell 120a JBD BMS is no longer being produced. When our current stock is sold, no more will be made.

We will be replacing this model with a brand new BMS that has been designed in America (and programmed in Canada) by Overkill Solar.
The new BMS is called The Pathfinder BMS, and we are working around the clock to get it ready for sale. Check back for more info later.

When it is closer to being ready, it will be available for pre-order. Sometime in June 2024, if all goes well.

Out of stock

SKU: 4s120a8ga24 Categories: ,


User Manual: Click here to download the manual (PDF)

BMS For 4 cell, 12v volt Lithium-iron-phosphate DIY batteries.
120 amp continuous charge or discharge current.
Low Temperature Charging cutoff at -1c.
The Apps allow you to monitor SOC (state of charge), Current, Voltage, cell balance, temperature, and more.

Bluetooth Module is included, Balance wires are included, USB module is an additional purchase.
Fully programmable.

If you choose to add crimped copper lugs, the high current wires will be hydraulically crimped into a single tinned copper lug on each side, and finished with heat shrink tubing.

Final assembly, testing and calibration is done in Naples, Florida. Units with 8 gauge wires and/or crimped lugs are assembled in Naples,  FL. The BMS is manufactured in China.

To view or change Parameters, there are 3 ways to connect to the BMS. All 3 applications are free.

Click here for Software Downloads and Support Resources.

A great resource for general DIY power education is www.Mobile-Solarpower.com

FYI for experimenters: The BMS communicates with a 5v TTL UART at 9600 baud. It is directly compatible with Arduinos, etc.
We have written a new Arduino library for the BMSs, now available on the downloads page. The beta version allows you to read all the monitoring parameters and switch charge and discharge on/off. Future releases will have full read/write capability. A python library is also in the works.

Additional information

Weight 1 lbs
Dimensions 6 × 4 × 1 in
Wire Size:

10 gauge x 12" (discontinued), M6 Threaded Terminals, 8 gauge x 12" (Standard), 8 gauge x 24" (+$22), No wires (-$8)

SKU 4s120a8ga24
Product ID 5008146

2 reviews for 4s BMS 120a LifePo4 with 24″ 8ga Wires

  1. Brian P

    So far I am really liking this BMS and the service/warranty provided by Steve. My first time building a “battery” using 4 LifeP04 cells I got from a buddy of mine. Great instructions, easy to set up. Bluetooth works great as well. Thanks Steve!

  2. Steve Stalker

    Overkill is one of the best company’s I have purchased electronic devices for projects. The bms I purchased 2 years ago worked flawlessly until I decided to move the cells to a new container. The cells came from China and I forgot that red and black don’t always mean the same thing. So yes I hooked them up to the bms backwards and burned out the bms not once but twice. Overkill noticed what I was doing when I sent in a picture and we got things straightened out. What other company would honor a warranty 2 years later for my dumb mistake. I would highly recommend Overkill for your BMS needs. Thanks Overkill.

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