4s BMS 120a LifePo4 with 12″ 8ga Wires

(2 customer reviews)


  • Comes with 12 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

In USA Stock, Ships within 2 Days

The high current wires will be hydraulically crimped into a single tinned copper lug on each side.

Free Shipping

All domestic BMS orders ship for free via Priority Mail.

International shipping cost will be calculated at checkout.


1 Bluetooth module is included with each BMS.

You may want to add a USB communication module

SKU: 4s120a8ga12 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 4s120a8ga12
Product ID 5008145

2 reviews for 4s BMS 120a LifePo4 with 12″ 8ga Wires

  1. Eric Hansen (verified owner)

    Package arrived in good time (shipped to Canada) with no damage. Installed the 120amp 4s BMS on a DIY Lifepo4 280 ah battery. It was easy to set up with the app and has worked flawlessly!

  2. Adam MacDonald (verified owner)

    Great to have the peace of mind, education, and support afforded by the team at Overkill Solar. I built 3 DIY 300AH batteries with Ali Baba cells from Basen (great quality by the way). The BMS arrived very well packaged and with great instructions on how to assemble the battery. I’m up in Canada and my heart sank a bit when I saw UPS arrive (usually they charge insane import fees from the US). Luckily it seems like the shipping included these fees! The three units I ordered arrived in little under a week, really quick.

    Now some negatives: the Chinese software is beyond janky. This isn’t the fault of the guys at Overkill Solar, but be warned that especially for multi-battery units, you should buy a Victron smart shunt or something similar. Relying on this software will screw you over at some point. Plus, switching between multiple BMS’ in the software is not always as easy as it should be. I sort of expected this, but just keep it in mind. Oh, and do NOT press the lock button no matter what, haha.

    I would upload an image of my build, but I don’t see an option for it. I will say these BMS units will be my go to in the future when I build another 24 batteries.

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