8s BMS 100a LifePo4 Battery Management System for 24v DIY Batteries, Programmable, Bluetooth Included.

(10 customer reviews)


  • Includes a Bluetooth communication module.
  • BMS For 8 cell, 24v volt Lithium-iron-phosphate DIY batteries
  • 100 amp continuous charge or discharge current
  • Low Temperature Charging cutoff at -1c (2 probes)
  • Remote shutoff switch
  • Fully programmable with IOS app, Android app, or Desktop app

The high current wires will be hydraulically crimped into a single tinned copper lug on each side. – Not available with the threaded terminals or no-wires options.

SKU: 8sBMS Category:


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

3D model: click and drag to rotate, or download the STEP file.

BMS For 8 cell, 24v volt Lithium-iron-phosphate DIY batteries.
100 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.

This unit has a connection for a remote shutoff switch. Useful for storage or security.

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 Denver, CO or Naples,  FL. The BMS is manufactured in China.


Example of a complete 8 cell battery with BMS:

Example 8s Battery

Click here for detailed assembly instructions for this battery. PDF

To view or change Parameters, there are 3 ways to connect to the BMS.
1. Bluetooth module to IOS app. The app is on the Apple app store, it is free to view operational data, but costs $6 to view and change parameters.
2. Bluetooth module to free Android app. (download this version, don’t get it from the play store)
3. USB module to PC/desktop application. This application is free

IOS app is on the Apple app store. Search for “xiaoxiangBMS

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), 8 gauge x 12" (+$6), 8 gauge x 24" (+$14), No wires (-$8), M6 Threaded Terminals (Standard)

10 reviews for 8s BMS 100a LifePo4 Battery Management System for 24v DIY Batteries, Programmable, Bluetooth Included.

  1. Edward (verified owner)

    Admittedly all I have done is install two of these on a new 2x8cell 24V LiFePO4 battery made with the cells available on this site, and run a few cycles …. but I am very impressed. I wanted to transition from LA AGM batteries to Li, but was hesitant due to the price. However, ‘building’ them yourself (thank you YouTube…) for less money with this BMS was an attraction I could not resist.

    Very pleased to say that the build was exactly as easy as suggested – the instructions are simple because the process is simple.

    And it just works. As soon as I wired it up the BMS was visible on the iOS app, which is actually quite well done. Seamless monitoring, with everything I need/want to know.

    Components were well packaged. Free swag was appreciated …. I do not remember ordering the lugs for the small wires, but they were thoughtfully included.

    Minor issue- for a 2×8 arrangement the 8-gauge upgraded wires were a little short for complete elegance of wiring, but this is definitely a minor quibble. Should have gone with the longer ones.

    Very impressed overall. I now have a significantly upgraded battery , and putting it together was just FUN.

    Now let’s see what it is like after a few cycles 🙂

  2. Tomas (verified owner)

    clearly, robust, perfect function, fast delivery,well packaged, thank you

  3. nwillitts (verified owner)

    i have 20 batteries,3 8s BMS and 1 4s BMS.works flawlessly!packaged well.will buy more.

  4. Alexander Kristiansen (verified owner)

    Everything is great with this product. Quickly shipped to Norway with tracking. Works very well. Easy to set up. Outstanding manual. Great support from Steve and the most important thing for me – low temp cut-off since I live in a cold environment.

    5 out of 5 stars for me!

    PS Hope they will add a 16s BMS to their webshop 🙂

  5. Abraham McBride

    This is a high-quality product and Steve is extremely helpful and responsive. The user manual he wrote is wonderful and really helpful for beginners. There are cheaper BMS options out there, but this is an extremely high-quality option if you can afford it. It comes set up perfectly for Lithium iron cells but is fully and easily customizable. I have already tweaked a few settings for a more conservative charge profile.

    This ISO app seems to work really well (cost a few bucks to change settings)
    The android app is rather buggy, but it is definitely useable. I saw that other places and was concerned it might be too hard to use. It really works well enough. You have to reconnect the BMS every time you use it but that is done in about 5 sec in the app. The app often freezes when I open it if it has already been running. Restating the app usually fixes any issues. I have always been able to eventually do anything I wanted to. It just sometimes takes time (2-3 mins), but honestly, it works much better than the Renogy app so I can’t really complain.

    One more lovely thing, when I opened the BMS there was a little quick instruction and guarantee from Steve and it said:

    “Unlimited Returns: If you have any problems with this BMS, we will take it back.
    If it isn’t working right I will replace it.
    If it’s totally fried I will refund your money.
    This includes anything you did to break it.”

    Now that’s a really phenomenal guarantee!

    Thank you for all your help, Steve!

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  7. Riley (verified owner)

    BMS works exactly as advertised, I like the multiple interface options – working on setting up the arduino display right now so I can monitor without needing a phone or laptop.

    I destroyed the first BMS I received by wiring in reverse polarity. Totally my mistake, beginner error, but Steve was super quick on responses and sent me a new one immediately. Arrived two days later in Canada. It’s a rare thing to find that level of support these days. Nice to know there’s a reliable human being standing behind the product. Can’t recommend highly enough!

  8. Scott (verified owner)

    Very happy with the 24 volt 100amp bluetooth BMS! I tried 2 other brands before finding overkill Solar . Very dependable and can take a beating…. While installing a second set of batteries and a second overkill BMS in tight quarters, the positive battery line touched the metal case of the 1st bms – not once – but twice. Sparks everywhere. I figured the BMS was toast – but no – still works as it should!

  9. Austin Moore (verified owner)

    Incredible BMS! Got one 8s 24v, tried it out and was soo impressed got another one for my older LiFePo4! Cables have really nice silicone and very flexible. Same for the balance cable! They give you plenty of cable for whatever arrangement of cells you could have and use 22awg. US based and incredibly fast shipping! Ordered on a Sunday night and got it on the following Wednesday. I plan on expanding my battery array in the future and when that happens, you can bet I’ll buy my BMS from here!!!

  10. Topper

    Very easy plug n play with in-depth instructions. Completely preset out of the box. I highly recommend the App download from overkill with the extra features. Android Bluetooth can get laggy when the unit is aggressively balancing a larger capacity mismatch, but still works awesome once caught up. USB works well. Capacity meter is very accurate after only a few cycles to internally calibrate.. Silicone wires are extremely flexible, although for my particular application, terminals would have been a better choice(my bad). My 2-8s 24 volt BMS’s have been bullet proof thus far. One has to appreciate your level of service Steve. Thank-you kindly..
    P.S . I’ll be ordering more in a few months..

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