A Lithium Ion Battery Management System

Description

Generally BMS's come with a big bunch of wires and some galvanic insulation to handle common mode voltage. I have decided to design a modular BMS using Bluetooth Low Energy to get nearly completely rid of the horrible wires. The result is cool. Regarding passive balancing, power dissipation is generally limited to a few watts per module. Thanks to tough SMD power resistors and fans, my modules are capable of a continuous 50 watts dissipation. This provide fast balancing and can be used to test the capacity of the module from time to time.

Project Logs

Collapse

Balancing video
Michel Kuenemann • 05/26/2017 at 12:38 • 0 comments

This 2 minute footage shows balancing in progress.
Explanations are embedded...
Conclusion: balancers validated...
15 balancing modules installed this evening
Michel Kuenemann • 05/21/2017 at 20:50 • 1 comment

I managed to finish the assembly of the balancing cards today and I installed them seamlessly on the battery modules. The result is really cool. Performance tests are in progress.

General view of the 10 kWh string:
Each (70-element) module is equipped with a balancing card placed on top of it. This card continuously measures the module voltage and starts to dissipate power whenever the module voltage crosses a certain limit (can be setup up to 4.2 Volts).
A close up on the modules
The first things to notice are the "large" 60 x 60 x 10 mm fans. Thanks to them, each module is capable of a 50 watt continuous power dissipation. The square components with a black on white hexadecimal figure on them are the BlueTooth Low Energy modules (Zentri AMS001). Each BMS card is managed by an NXP LPC824 Cortex M0+ microcontroller featuring a very clean 12 bit ADC, among many other cool things.