The Mercedes AMG HPB80 is a dielectric cooled PHEV battery pack. First introduced in detail by Mercedes in 2021 this battery pack is worth a more detailed review.
We know a number of the specifications for this pack and hence can estimate others. However, we do not know the cell that is used in this pack, hence it is difficult to get too deep.
- Total energy = 6.1 kWh
- Peak = 150 kW10s
- Continuous = 70 kWcont
- Configuration = 112s 5p
- Total number of cells = 560
The battery pack sits above the rear axle with an electric motor in the rear axle in a P3 configuration.
- Pack Mass = 89 kg
- Cell Mass = 39.2 kg
- Pack-Cells = 49.8 kg
- Cell to Pack Mass Ratio = 44 %
This pack is designed around the 21700 cell format. Hence we know that the cell mass is between 68g and 72g. Taking 70g the total cell mass is 39.2kg and giving this pack a low cell to pack mass ratio of 44%.
In the images you can see that the cells are arranged in a 5P configuration and that there are 7 rows of cells arranged end to end. In the bottom right image you can see 16 layers of cells. Thus we have 16 x 7 = 112S 5P
- Cooling power = 10kW
- Operating set point = 45°C
- Cooling fluid = dielectric
- Volume = 14 litres
- Dielectric to water-glycol heat exchanger.
- Low temperature vehicle radiator.
The dielectric cooling system has been very carefully designed to be self contained and not serviceable. The assumption is this is to avoid someone wrongly topping up the fluid and destroying the dielectric properties and possible destroying the battery.
The images show the dielectric coolant flows around the mid-section of the cells.
The temperature set-point for this pack is 45°C. This is done to reduce the resistance of the pack as we know the internal resistance of the cell decreases as temperature increases.
In a pack that uses cooling plates this high operating temperature would be difficult as it leaves a narrow margin of operation. With dielectric cooling it is possible to react faster as the coupling to the cell is closer.
- Cell format = 21700
- Make = Lishen
- Model = LR2170LH
- Energy = 10.9 Wh
- mass = 0.07 kg
As discussed earlier we don’t know exactly what the cell is. We do know it is a 21700 format and the total energy is 10.9Wh
Assuming the cell is a nominal 3.6V that would put the capacity ~3Ah. Quite a small capacity even for a power cell in this cell format.
The larger HPB150 battery pack is 13.1kWh and has 1200 cells, again giving a cell energy of 10.9Wh and hence reinforcing that this is using a 3Ah cell.
The cell connections are very interesting and in the image below you can see the clip that is welded to the positive end of the cell. This clip pushes onto the bottom / negative end of the next cell in series.
This clip design does bring up some questions:
- What is the resistance of a spring loaded joint?
- What is the resistance over time of this electrical joint?
- An assembly failure mode appears to be that the tabs could be bent and even pushed to short against another cell?
The cooling jacket design and electrical connection looks like the design from Kreisel .
- Gravimetric Energy Density = 68.5 Wh/kg
- Power Density
- Peak = 1685 W10s/kg
- Continuous = 787 Wcont/kg
A very high power capability when benchmarked against everything else in our Pack Database.