Page 8 - EngineerIT November 2022

WIRELESS BATTERY MANAGEMENT SYSTEMS

which contains multiple cells. Natural maintain the safety of the assembly process and to protect production line workers,
production variations mean that each rigorous safety protocols are applied.
cell has individual characteristics that There are, then, strong reasons for OEMs to introduce a robust wireless technology in
vary within a specified tolerance range. new EV battery system platforms.
To maximise battery capacity, lifetime
and performance, the key parameters wBMS – a new smart approach
of battery operation – voltage, charge/ The wBMS is a complete solution that is easy for the automotive manufacturer to
discharge current and temperature integrate into a battery pack design. It includes a wireless cell monitoring controller
– need to be monitored and logged (wCMC) unit for each battery module and a wireless manager unit to control the
individually for each module. communications network, which connects multiple battery modules wirelessly to the
This is the reason why an EV’s battery ECU. Beside the wireless section, each wCMC unit includes a BMS that performs highly
requires a means to transfer data from accurate measurements of various battery parameters so that the applications processing
each module or cell, where voltage and unit can analyze the SOC and SOH of the batteries.
temperature are measured, to the ECU
processor (see Figure 1). Traditionally, While the wBMS technology has taken full advantage of eliminating the wiring harness
these connections have been made design and assembly issue, there are further areas within the battery lifecycle where
with wires: wired connections have the additional value will be generated:
advantage of being familiar and well • Battery assembly – the only connections that a battery module requires are the power
understood. terminals, which can readily be made in a highly automised process. By eliminating
manual labour for assembly and testing, this also avoids safety risks to assembly line
The disadvantage of a wired workers (see Figure 2). Furthermore, the modules can also be tested and matched
BMS before installing inside the battery.

However, there is also a list of • Servicing – secure wireless capability means that the condition of the battery pack can
disadvantages related to wires: a copper be conveniently analysed by diagnostics equipment in an authorised garage without
wiring harness adds additional weight touching the pack. If a malfunction is detected, a faulty module can easily be removed
and occupies space that, if filled by a and replaced. A wireless configuration simplifies installation of a new module in the
battery cell, would provide extra energy battery system.
capacity. Additionally, the wiring needs • Second life – by the increasing number of vehicles, a market is emerging for second
to be fastened on battery housing life batteries recovered from scrapped EVs and repurposed for applications such as
structures and connectors can potentially renewable energy storage systems and electric power tools. This additionally creates
suffer from a mechanical failure a new source of value for EV manufacturers, which are responsible for the recycling or
especially under vibration and shock disposal of the batteries in scrapped EVs since wBMS allows a simpler integration of
conditions. the modules for second life applications.
In other words, wires increase
development effort, manufacturing
cost and weight, while also reducing
mechanical reliability and usable space.
This results in reduced driving range.
By removing the wiring harness, the car
manufacturer gains new flexibility to
meet a vehicle’s design requirements for
the form factor of its battery pack.
The complexity of a battery’s wiring
harness also makes the assembly of a
battery pack difficult and expensive:
wired packs have to be assembled and
the connections have to be terminated
manually. This is a costly and hazardous
process because high voltage EV battery Figure 2: The wBMS eliminates the BMS signal wiring harness to enable automated, robotic
modules are supplied charged. To production of battery packs.

EngineerIT | November 2022 | 8