Ultra-High Energy Battery System
for Electrified Commercial Vehicles
from BorgWarnerKnowledge LibraryUltra­High Energy Battery System for Electrified
Commercial Vehicles
BorgWarner’s ultra­high energy battery system exploits the full potential of its Akasol
battery technology to lower the total cost of ownership for electrified commercial vehicles.
Dr. Martin Busche, Director Global Research & Development, BorgWarner Akasol, Germany
Dr. Matthias Fleckenstein, Director Systems Development, BorgWarner Akasol, Germany

History and Background(eCV) demands significantly different priorities

Various battery formats and chemistries havefrom its batteries. For cars, initial purchasebeen experimented with for vehicle propulsion

cost, energy and power density are primary

since the early 1900s. However, the diversity ofconsiderations, but for the eCV market, thetoday’s

thetotal cost of ownership (TCO) is critical, anddevelopment of a universal battery type to suit

this largely depends on how many times the

all applications. Instead, battery designs mustbattery

become more specialized to meet the specificvehicle’s life. Mechanical robustness, longevity,requirements of each sector. For example, thecompact dimensions, and light weight of theelectrified commercial vehicle (eCV) market isbattery assume much higher importance for theexperiencing rapid growth, since buses andcommercial vehicle market, where continuous,trucks can improve sustainability by providing

long­term usage must be assured while keeping

higher transportation efficiency compared tovehicle payload capacity as high as possible.

mobility

solutionsprohibits

must

bereplaced

throughout

thesmaller vehicles. To properly realize theseadvantages, the power source needs to beTo

tailored to the operational demands of eachdeveloped an ultra­high energy (UHE) battery

type of eCV.

system for energy intensive electric drivetrain

address

thisneed,BorgWarnerhasapplications operating at up to 750V. As
Ideas for the development of a next­generation

BorgWarner’sultra­high energy battery pack date back to(CYC)

2018, when BorgWarner visited major electric

benchmark for energy density in the eCV

bus and truck suppliers to gain a thoroughmarket, this is employed as the power source inunderstanding of their future needs. In 2019,

the UHE battery pack. The new system provides

this resulted in the battery module design thatbattery life of up to 4,000 cycles. It is also

now forms the major building block of thesufficiently versatile to be matched to abattery pack discussed in this paper.

customer’s usage profile; cells can be optimized

battery

award­winning
modulecylindricalalreadysets

cellthetowards maximum power density to takeBattery Optimization for eCVs

advantage of quick charging stops (opportunity

Compared to a passenger battery electriccharging) for an urban bus, or they can bevehicle (BEV), an electrified commercial vehicle

optimized towards maximum energy density for

BorgWarner Knowledge Library 2022

1long distance traffic such as buses using overnightand 300 mm high. This compact, energy­dense

charging facilities, intercity coaches, and trucks.

solution means that, for example, city buses
and intercity coaches can be equipped withCYC Module:
Building Block

TheBattery

Packbattery system capacities of 400 kWH to 1000
kWh depending on vehicle size ­ twice as highThe design of the CYC battery module is based

as the present generation of batteries.

on the 21700­format cylindrical lithium­ion(Li­ion) cell. To achieve the high energy density

Production of 6 AKM battery packs is also

required and the necessary charging andplanned; these derivatives require low R&D

discharging power, the type of cell chosen iseffort, in essence simply scaling the length ofspeciallyandthe pack. The smaller packs could be used incommercial applications with an additional

conjunction with 9 AKM for vehicle applications

focus on cycle life. Each CYC module contains

where a mix of different pack sizes would make

600

are

the most efficient use of available installation

configured as 20 serial connections of 30

space. Mixed pack sizes can be handled withparallel­linked Li­ion cells, providing a maxi­

ease

mum module voltage that is below the electricalmanagement technology.

designedcells;

infor

standard

professional

form,

thesebythe Akasol

multi­string

battery

shock threshold for safe handling during
production and maintenance. However, alter­

Battery Management and Coolingnative cell configurations are possible by

The Akasol

altering the current path routing within the side

consists of an in­house developed battery

PCBs of the battery module. The module

management unit (Master) & cell supervisingachieves an energy density of about 221 Wh/kg.

circuits and their corresponding software. Itbattery

management

systemprovides primary safety functions including

Ultra­High Energy Battery Pack
Specification

over­temperature,

Nine CYC modules are connected in series todetailed diagnosis of all actuators and sensors ascreate a 9 AKM battery pack providing 98 kWhwell as innovative high level battery managementof energy. The nominal voltage output is 665 V,

functions, e.g. battery state estimation.

over­current

over­/under­voltage

protection

butalsoandperforms

with a minimum and maximum of 520 V and756 V respectively. The pack weighs 560 kg

Theand measures 1,720 mm long, 700 mm wide

extremely effective liquid cooling at module level.

Battery System 9 AKM 150 CYC

BorgWarner Knowledge Library 2022

UHE

batterypackisequippedwith

Module with cylindrical lithium­ion cells2This is indispensable for safety, providing evendurable stainless­steel housing protects thetemperature distribution and operation withincomplete battery pack against damage in a

the preferred temperature range, and also forcrash situation. The system is also shielded

performance, ensuring high availability of powerfrom external thermal loads such as a fuel fireand energy, and contributing to slow aging andby surrounding the battery cells with sufficient

long life of the battery cells.

thermal insulation material to protect against
environmental hazards. An efficient cooling

Safety in Operation

system and predictive algorithms within theThe main safety consideration during battery

battery management system software add apack development was the prevention of any fire

further layer of safety.

or explosion hazard. A combination of active andpassive safety devices at both CYC module andThe intrinsic safety of the UHE battery packs isbattery pack level provides maximum protection

proven in use, as the first buses and trucks toagainst fire propagation resulting from a thermal

be equipped with them have been running inevent.

major cities since 2020 without incident.

Within the CYC module, each cylindrical cell is

Charging and Maintenancephysically separated from the next by a defined

The UHE battery pack can be charged,

gap, that results from deep evaluations bydependent on cell type, at a rate of up to 1C

simulation and validation, and covered by anwith quick charging and is also suitable for use

optimized potting compound. In the unlikely

in fast charging infrastructure up to 500 kW

instance of a thermal event occurring at cell

power on vehicle level. All significant electroniclevel, this prevents thermal propagation between

parts aside from the CYC modules are placedneighboring cells and allows controlled and safein a removable contactor box. In the unlikely

dissipation of hot gases. Adjacent cells inside theevent of a field failure due to a fault in themodule or in the neighboring module are notbattery electrics or electronics, the uniquetriggered and do not even change their state ofservice concept of the UHE system allows thischarge; in fact, the battery system is equipped

electronics compartment to be exchanged

with a special thermal runaway detector (TRD) thateasily without the need for high­voltage trained

monitors the internal pressure, cell temperatures andtechnicians or the necessity to demount thevoltage behavior to identify a single cell thermal

battery pack from the vehicle.

runaway within a pack. Furthermore, the wire
bonded cell connections to the side PCBs act as

Environmental Sustainability

a cell individual fusing concept in the case of an

BorgWarner’s UHE battery system is rated as ainternal or external short circuit. Adjacent CYC

highly sustainable battery solution according to amodules are separated by fire retardant materialsTÜV (Technischer Überwachungsverein) audited

to additionally prevent fire propagation fromcalculation method in Germany. Several factors

module to module.

can be cited to demonstrate its sustainability:

Further software and hardware safety elements­ Lightweight solution: Increased energy den­are incorporated at battery pack level. The CYC

sity reduces the total weight required for themodule combines a rigid steel construction withbattery system, which has a positive effect on

further bracing elements between the modules. A

the vehicle's energy consumption.

BorgWarner Knowledge Library 20223

­ Longevity of battery cells: The very high cycle
life of carefully chosen battery cells is extendedby intelligent mechanical and thermal integrationand sophisticated sensors. In the TCO­driven
commercial vehicle business, maximizing thefirst life application of the batteries reduces thenumber of battery changes required throughout
a vehicle’s lifetime. Moreover, the environmental
sustainability (e.g. CO2 footprint) is maximized
by energy density.
­ Extended circular value stream of thebatteries: This includes maximum recyclability of
the raw materials, and/or finding second life
applications for used batteries. For example,
earlier generation battery systems can be takenbackfrom

OEMs

andrepackaged

into

stationary storage applications to serve theeconomy for another decade.
­ Higher availability of energy from the vehicle’s
batteries:

The

consequent

increaseinoperational range facilitates further intercity bus
and light­, medium­ and heavy­duty truck
applications to be electrified, replacing internal
combustion engines and reducing dependency
on fossil fuels.

Summary
Mechanically robust, intrinsically safe, easily
scalable and offering relatively low invest costs
perkWh,BorgWarner’sultra­highenergy

solution for long distance transport sets newenergy density standards for bus and truck
applications and firmly positions BorgWarner as
an innovation driver in the field of high energy
batteries.

Contact
Email: technology@borgwarner.com
For more information please visit
borgwarner.com
BorgWarner Knowledge Library 20224