Audi Q6 e-tron debuts ‘predictive’ thermal management

The Audi Q6 e-tron is the brand’s first electric vehicle built on the new Premium Platform Electric (PPE), a collaborative effort with Porsche for the Macan. 

It features various trailblazing advancements, including redesigned prismatic battery cells, a predictive thermal management system, and E³ 1.2 electronic architecture.

“The Audi Q6 e-tron represents the true embodiment of Vorsprung durch Technik as we take the next step in our transformation into a provider of premium electric mobility,” remarked Andrew Doyle, who at the time of the Q6 reveal was Audi UK director but has since accepted the CEO role at Australian car dealership group Peter Warren Automotive. 

“Its arrival not only brings huge advancements in battery recharging, on-board technology, and driving dynamics, but also signals the start of Audi’s most ambitious product initiative in history.”

Each version of the five-seat Q6 e-tron features a 94.9kWh battery pack comprising twelve modules and 180 prismatic cells.

Dual compact electric motors provide all-wheel drive (including on the sporty SQ6 version) and rear-drive variants with notably extended range are also offered.

The standard 285kW Q6 e-tron Quattro accelerates from 0-100 km/h in 5.9 seconds, with a top speed of 210 km/h and a claimed driving range of up to 625km. A 225kW single-motor rear-wheel drive Performance variant extends range to 641km in return for a slower but still-respectable 6.7-second 0-100km/h time and the same top speed.

On the other hand, the high-performance SQ6 e-tron Quattro boasts up to 380kW in boost mode, accelerates from 0-100 km/h in 4.3 seconds, reaches a top speed of 230 km/h, and offers a range of 598 km. 

The new-generation electric motors are said to increase the range by 40km compared to earlier designs thanks to their lighter and more compact construction.

Audi’s PPE architecture incorporates 800-volt technology, enabling the battery pack to charge from 10-80 per cent capacity in approximately 21 minutes due to a maximum recharge rate of 270 kW.  When using the fastest available DC rapid charger, a brief 10-minute charge can add 300km of range.

Additionally, a high-efficiency two-stage regenerative system, used for around 95 per cent of everyday braking, can recover energy at up to 220 kW.

When the vehicle is connected to a fast-charging station operating at 400 volts, the Q6 e-tron is capable of ‘bank charging’, a feature that automatically divides the 800-volt battery into two batteries with equal voltage.

Then, as Audi explains, “Depending on the state of charge, both halves of the battery are first equalised and then charged simultaneously” at up to 135kW per bank.

Predictive thermal management

Intelligent thermal management is crucial to battery pack performance and longevity.

A key advancement in this area is predictive thermal management, which considers information from navigation systems, route specifics, departure schedules, and user patterns to anticipate cooling or heating requirements in advance.  

By strategically applying these temperature modifications at opportune times, the system boosts the battery’s performance.

This forward-thinking strategy not only streamlines charging procedures but also leads to quicker charging speeds, enhanced energy efficiency, and an extended battery lifespan, improving the ownership experience.

For example, as a driver approaches a high-power charging (HPC) station on their intended route, the predictive thermal management system pre-cools or pre-heats the battery. 

This proactive measure improves the battery’s ability to absorb energy, leading to a decrease in total charging time. When encountering steep inclines ahead, the thermal management system pre-emptively cools the battery to avert thermal strain.

When the driver opts for Efficiency mode in the drive select menu, battery conditioning activates at a later stage, potentially extending the real-world range based on driving habits. On the other hand, dynamic mode prioritises peak performance. Yet, if the prevailing traffic conditions hinder dynamic driving, the thermal management system adjusts accordingly to conserve energy used for battery conditioning.

In situations where predictive data is not available, a standard algorithm takes charge of managing the thermal conditions of the battery, adjusting to the driving circumstances at hand, and then, depending on the driving mode selected, such as efficiency or dynamic mode, the battery conditioning is tailored to either extend the vehicle’s range or enhance its performance capabilities.

Two heat pumps

A glycol coolant circuit controls the temperature of the battery pack, electric motors and power electronics. 

During higher ambient temperatures, the battery can also be cooled by the refrigerant circuit. A heat exchanger is used for cooling via the refrigerant circuit. It transfers the heat between the refrigerant circuit and the coolant in a dedicated circuit for controlling battery temperature.

Two types of heat pump are used in the Q6 e-tron to reduce the amount of waste heat generated.

An air-source heat pump is added to the water-glycol heat pump so that in addition to the waste heat from the (oil-cooled) electric motors, (glycol-cooled) power electronics and (glycol-cooled) battery, ambient air can also be used as a heat source for the interior.

Audi also developed an 800-volt PTC (positive temperature coefficient) air heater to support interior temperature control to reduce the heat losses associated with water-led heating circuits at low ambient temperatures.

Direct heating of the interior via the air circuit also increases the heat-up/response speed for increased cabin comfort and faster windscreen demisting or de-icing.

Battery temperature is constantly monitored, even then when vehicle is parked, and the thermal management system can be activated at any time to protect the cells in extremely cold or extremely hot weather conditions.

Prismatic battery cells

A prismatic battery cell is a type of lithium-ion battery cell that features a rectangular or square shape, in contrast to the cylindrical shape of traditional battery cells. The electrodes – anode, separator, and cathode – are stacked in layers within the rectangular prismatic casing to enable a more efficient use of space in battery packs where optimisation is crucial.

The Q6 e-tron battery pack comprises 12 modules containing a total of 180 prismatic cells, a departure from Audi’s previous battery systems, where, for comparison, the Audi Q8 e-tron battery consists of 36 modules and 432 cells.

The new larger cell size in the Q6 e-tron battery suits the 800-volt architecture, delivering a balance of range, charging performance and repairability.

A cell composition ratio of nickel, cobalt, and manganese at 8:1:1 reduces cobalt content and increases nickel content for higher energy density.

The modular battery, designed for both high and flat floor models, takes up less installation space, is lighter, and integrates more seamlessly into the vehicle’s cooling system while reducing the need for additional cables and high-voltage connectors. 

Screw connections has also been minimised and the electrical connections between modules are shorter, reducing power loss and weight while cutting manufacturing time from approximately two hours to just 55 minutes.

An updated battery housing uses a cooling plate that acts as a structural component, removing the need for an extra floor panel and improving thermal conductivity with the modules using a heat-conducting paste, while new protective side skirts made of hot-formed steel enhance stability by connecting to the body instead of the battery.

Better underbody protection, made of fibre composite material, reduces weight, shields the battery, and boosts thermal insulation for better cooling and heating efficiency.

The battery management controller (BMCe) is designed as a central control unit positioned within the battery pack for regulating current during fast and battery-friendly charging. 

It serves as the main electrical control hub and gathers information from twelve cell module controllers (CMC) that monitor module temperature and cell voltage.

This data, including the state of charge (SoC), is then transmitted to the high-performance computer HCP4, a key component of the advanced electronic architecture (E³ 1.2). Here, the BMCe collaborates with the predictive thermal management system to adjust cooling or heating settings, ensuring optimal battery performance.

E3 1.2 electronic architecture

The PPE platform’s E³ 1.2 electronic architecture brings forth a new era of innovation, facilitating the integration of larger, higher-resolution screens and seamless wireless updates. 

It also introduces a standardised infotainment platform without the need for smartphones, allowing control of numerous functions through a self-learning voice assistant and a digital assistant visualised by an avatar in the dashboard. 

Most importantly, the scalable design of the electronic architecture enables standardised use across different vehicle platforms, reducing development and production complexity while facilitating future innovations.

The architecture prioritises security and the networking of domain computers, control units, sensors, and actuators through the Audi high-performance computing platform (HCP), preparing Audi for safely managing increasing complexity in the years ahead. 

All new PPE technologies

The Q6 e-tron will be manufactured at Audi’s Ingolstadt factory in Germany, where the site has been transformed into an all-electric assembly plant, now equipped with the latest PPE technologies for the custom electric platform. These technologies are considered crucial for Audi’s future vision to expand its global range of all-electric models.

Australian Launch

Audi has invested over AU$400 million to train 8300 Ingolstadt factory employees in anticipation of the Q6 e-tron launch, and while the model has been confirmed for sale in Australia, specific pricing and release dates are yet to be disclosed.

However, based on European pricing, it is estimated that the Q6 e-tron will start at around A$124,000, with the SQ6 e-tron expected to be priced at roughly A$156,500.