2024 Audi MHEV plus Battery

The 2024 Audi MHEV plus battery and drive system is all part of the Premium Platform Combustion (PPC) architecture.

There are a number of configurations of MHEV system in the 2024 line up:

• 12V with a 154Wh battery
• 48V with a 456Wh battery
• 48V with a 1760Wh battery and given the name MHEV plus
  • Chemistry = LFP
  • Nominal voltage = 46.2V
  • Nominal capacity = 37Ah
  • Configuration = 14s 1p
  • Cooling = liquid

The MHEV plus system is more capable in terms of power and energy. Thus allowing the engine to be switched off when cruising and able to drive the car in slow traffic.

The MHEV plus battery is located above the rear subframe.

This post has been built based on the support and sponsorship from: Thermo Fisher Scientific, Eatron Technologies, About:Energy, Quarto Technical Services and Alvatek.

This larger battery pack has an output of ~20kW, based on the motor peak output being 18kW and assuming 90% efficiency for the motor and inverter. The motor has been optimised by Audi for efficiency in recuperation and is able to deliver 25kW to the battery.

The battery pack uses Lithium Iron Phosphate chemistry.

The battery target SoC is set lower [1]: “50 to 60 percent can work most efficiently because it can deliver high currents to the electric motor and store them during recuperation.” Set the car into sport mode and: “the system raises the target charge level to over 65 percent so that a lot of energy is available at the exit of the bend to support the combustion engine electrically.”

The battery cooling system is illustrated as running around the case.

Whatever cell format and orientation this will impose a temperature gradient on the cell, far from ideal.

Cell

• Manufacturer = A123
• Chemistry = LFP
• Format = Pouch
• Minimum capacity = 39 Ah
• Nominal voltage = 3.3 V
• Nominal energy = 128.7 Wh
• Mass = 0.983 kg
• Gravimetric energy density = 131 Wh/kg
• Volumetric energy density = 286 Wh/litre

As we get more data around this battery pack we will add to the benchmarking, for now we will leave you with an image from Audi’s animation of the system.

References

1. Drive technology, Audi Media Center