Battery system

Today this is most commonly achieved with cell-to-module construction: cells are grouped into modules, which are then assembled into a battery pack.

Cell-to-pack construction removes conventional modules and integrates cells directly into the pack. Cell-to-body designs go a step further by making the battery structure part of the vehicle body.

A typical battery pack consists of modules containing several cells.

Modules

Modules are a combination of cells. The number of cells in a module varies.

Architecture

The cells inside a module can be connected in different ways.

Serial connecting gives a higher voltage
Parallel connection gives a higher capacity.

Example 1

Below you see how modules on the Audi e-tron 55 are. There are 12 cells per module. They are grouped into 3 groups where 4 cells are connected in parallel. Then those groups are connected in serial giving it a 3 serial 4 parallel configuration (3s4p). With 60AH for each cell and a nominal voltage of 3.66 volts, this module has a capacity of 240AH and 11 volts.

Battery

Example 2

Below you see how modules on the Audi e-tron 50 are. There are 12 cells per module. They are grouped into 4 groups where 2 cells are connected in parallel. Then those groups are connected in serial giving it a 4 serial 2 parallel configuration (3s4p). With 60AH for each cell and a nominal voltage of 3.66 volts, this module has a capacity of 180AH and 14.666 volts.

Battery

Audi modules

| Module | No of cells | Config | Capacity AH | Nominal voltage | kWh | |—–|—–|—–|——|——| |e-tron 55 | 12 | 3s4p | 240AH | 11 volts | 2.640 kWh | |e-tron 50 | 12 | 4s3p | 180AH | 14.666 volts | 2.640 kWh | |e-tron GT | 12 | 6s2p | 129.2AH | 21.909 volts | 2.830kWh | |Q4 e-tron | 24 | 8s3p | 234AH | 29.16 volts | 6.825kWh |

Packs

Battery packs consist of several modules placed in a construction that is created to protect them and give them optimal conditions. Below you see a battery pack from Audi e-tron GT.

Typical the pack is placed at bottom of the car.

Audi Battery packs

Today all Audi models use Cell2Module technology

Battery pack configuration

	Cell type	Cells	Modules	Voltage	Cell config	Gross cap
e-tron 55	LGXN2.1	432	36	396	108s4p	95 kWh
e-tron 55*3	Samsung	432	36	396	108s4p	95 kWh
e-tron 50	Samsung	324	27	396	108s3p	71 kWh
e-tron GT	E66A	396	33	723	196s2p	93.4 kWh
RS e-tron GT	E66A	396	33	723	196s2p	93.4kWh
Q4 e-tron 50	LGX E78	288	12	350	96s3p	82 kWh
Q4 e-tron 40	LGX E78	288	12	350	96s3p	82 kWh
Q4 e-tron 35	LGX E78	196	9	350	96s2p	55 kWh
Q6 e-tron*1	LGX E78?	392?	16?	700?	192s2p?	110 kWh?
A6 e-tron *2	LGX E78?	392?	16?	700?	192s2p?	110 kWh?

Battery pack performance

In the table below you see the pack performance. See how Q4 has a higher density even the cell itself does not have a better density.

	Gross capacity	Net capacity	Max DC Charging	Weight	kWh/kg
e-tron 55	95kWh	86.5kWh	150kW	699kg	0.136
e-tron 55*3	95kWh	86.5kWh	150kW	699kg	0.136
e-tron 50	71kWh	64.7kWh	125kW	580	0.122
e-tron GT	93.4kWh	83.7kWh	270kW	630kg	0.148
RS e-tron GT	93.4kWh	83.7kWh	270kW	630kg	0.148
Q4 e-tron 50	82kWh	77kWh	125kW	493kg	0.188
Q4 e-tron 40	82kWh	77kWh	125kW	493kg	0.188
Q4 e-tron 35	55kWh	52kWh	100kW	344kg	0.160
Q8 50 e-tron	95kWh	89kWh	150kW	699kg	0.136
Q8 55 e-tron / SQ8	114kWh	104Wh	170kW	727kg	0.157

*1 Audi Q6 details are not yet confirmed.

*2 Audi A6 details are not yet confirmed.

*3 From January 2021 Audi uses Samsung cells on e-tron 55

What is next for Audi?

The problem with today’s approach with Cell2Modules is that the energy density on the battery system is much lower than on the cell level. This is because of all the structural elements in a battery that does not add any energy content to a battery pack.

Cell-to-pack construction can reduce inactive structural material by placing cells directly into the pack rather than into separate modules. This can improve pack-level energy density and reduce weight, but the implementation and benefits vary between manufacturers and battery designs.

On March 15, 2021, Volkswagen Group presented its battery strategy at Power Day. The following material reflects that 2021 strategy and should not be read as a current Audi model launch schedule.

See the complete presentation.