Wireless BMS as a Key Battery Technology
Image credit: GM (top-left Battery) - Texas Instruments (bottom left and right wBMS)
Maybe surprisingly for some of you, not all Battery developments deal with better cell chemistries or high-voltage components. Do you know that low-voltage (“simple” electronics) is also a crucial technology for Battery development?
In particular, one key technology under development at car manufacturers is the wBMS or wireless BMS (Battery Management System). The first OEM who will commercialise wireless BMS should be GM in their upcoming HUMMER but other OEMs like Renault have already announced wBMS in their EV Roadmap. GM disclosed that their wBMS will be supplied by Visteon.
Why is wireless BMS a key technology? Today modern cars include several km (yes, kilometres!) of cables. This complex wiring involves a cost, a weight and a risk of failure making diagnostic and reparation very difficult at car manufacturers. To cope with this problem, Tesla for example has a specific patent to reduce the number of cables.
Tesla patent for Wiring system architecture (reference US20190217794A1)
Inside the Battery pack, being able to reduce the number of cables is very important. Less cables means:
Less “dead” weight and less “loss of space” = more power and the energy density at the Battery pack level
Reduced risk of connection failure
Simplified Battery Pack production (= reduction of Battery cost)
Left: traditional BMS (wired) architecture; Right: Wireless-BMS
image credit: Analog Devices
In a wireless BMS, each module is interconnected via a wireless connection instead of a Can bus cable or an isolated SPI twisted pair. Communication is very similar to a WiFi (2.4 GHz).
From a technical point of view, wireless protocol also means
Low latency to join a complete network of measurement and control as soon as the car starts (the Battery is better monitored at start-up which is critical from a power management point of view)
Increased reliability (low rate of packet error) with 99.999% transmission success (packet error rate of less than 10-7) with ±2-mV accuracy
Very accurate and synchronised information (each 100 ms) = better understanding and estimation of SOC
GM said that their Ultium batteries equipped with wBMS will reduce wiring within the batteries by up to 90%. Additionally, the wBMS will enable the scalability of Ultium batteries across GM’s future lineup.
wBMS supplier list includes Visteon, Texas Instruments and Infineon.
