Hello Aisler Community!
We are Racing Power Münster (RPM), a new electric Formula Student team in our second season. During the construction of this years car, the RPX-02, we made the decision to work on a module based battery management system (BMS) for our main accumulator.
What is a BMS?
The BMS inside a battery system watches over the voltage and temperature of the cells. If any cell is getting too hot or the voltage low/high, a emergency shutdown is performed.
One other important feature of a BMS is the balancing. Since the cells are connected in series, a slight difference in internal resistance leads to a different voltage in each off the cell stacks. The result is an unequal charge of the cells but a normal voltage of the whole battery. If no measurement or balancing happens the battery may catch fire.
The Advantages:
Our old, global, BMS had a massive cable harness since every voltage from every cellstack of our battery needs to be monitored. This lead to an enormous amount of weight and a nightmare for installation.
In the attempt to reduce all wire harnesses in the new car, we opted for a module based solution.
Now we are down to a single twisted pair of wires coming from a combined 118. Another upside is that every communication cable inside the accumulator is isolated from the high voltage system. This enables a safer interaction with the system during installation.
All of this was made possible by the 4 Layer ENIG Beautiful Boards from Aisler.
Our cellstacks mount to the BMS with M5 screws. What is not shown here are busbars beneath the PCB that carry the current of the traction system.
The first iteration of the BMS had a slight mechanical design issue that was resolved by the fast turnaround time of Aisler and their great KiCad Integration. With that we made quick progress with this prototype.
We like to thank Aisler for the massive support to our project.