You don’t think about it often, but wiring is hefty. It’s one of the heaviest subsystems on a car, weighing in around 150 pounds in today’s more well-equipped models, though a simpler economy car car may have at least 50 pounds of copper wire. As the industry moves toward an “all-electric” future, finding ways to manage this weight will become vital as we pursue increasingly lighter, more efficient vehicles. While wiring schemes are becoming simpler thanks to technologies like CAN-Bus (which can reduce a complicated wiring harness down into a single pair of data lines), what if we just got rid of the wiring itself whenever possible? That’s what GM is planning with Analog Devices, a supplier that specializes in charging hardware for mobile devices, among other things.
One of the most complicated aspects of designing a lithium battery pack is the battery management system (BMS), which monitors each individual battery cell’s health to decide how to best charge the pack. If one cell were to go bad or fall out of the voltage range of its neighbors, it could spell disaster for the vehicle while driving or charging, so the BMS is wired to each cell to monitor for problems. Maybe you see the catch-22 here: for more battery capacity, more battery cells are usually necessary. More cells mean more balance wires, which quickly adds up in not just the overall weight of the battery, but also the development time that goes into designing a critical wiring harness.
The wireless BMS (wBMS) designed by GM and Analog Devices aims to reduce the internal battery wiring by 90 percent, making more room for more cells and reducing necessary weight—both of which will help EV vehicles further match the range and relatively low cost of entry that’s enjoyed by today’s traditional combustion-engine drivelines.
GM’s new tech should also significantly reduce the cost of offering a myriad of battery pack configurations for different vehicle classes. The number of cells doesn’t necessarily increase the inherent complexity of the pack, and GM won’t have to engineer different BMS modules based on the physical number of balance leads running out of the pack.
GM claims its advancements will also ease the recycling of battery packs into stationary applications (such as a solar battery bank) by simplifying the process of repackaging the cells and all their balance leads, but we presume this also means that a stationary wBMS master console is also in the works, which will need to talk to the wBMS modules inside the batteries.
Step by step, individual advancements like this will make all-electric vehicles increasingly efficient and viable on a mass-market scale.