3 Iterations Of BMW i3 And MINI Cooper SE Fast Charging Analysed

Here is how the curve changed, despite the power cap at 50 kW.

Today we will take a look a little bit into history and compare fast charging of three iterations of the BMW i3 (21.6, 33.2 and 42.2 kWh battery versions) and the related MINI Cooper SE model (32.6 kWh).

Those small electric cars are not expected to fast charge very quickly, but we would like to check whether BMW upgraded them in any way and what they offer. There are a few interesting findings in this report – small bricks in the foundation for further reports on newer models.

Data for this analysis comes from Fastned’s fast-charging network, which is also an invaluable source for info about charging.

Let’s first see the latest BMW i3 model, and then compare all four cars together.

Charging power vs state-of-charge (SOC)

The 2019 BMW i3 (44.2 kWh battery version) has a very flat charging curve with a peak charging power of 50 kW.

Comparison of charging power

The first comparison – of charging power curve – of three iterations of the BMW i3 and the MINI Cooper SE, reveals that BMW has increased the battery capacity (through using more energy dense cells), but probably did not touch the charging systems.

As a result, the power looks like it would be capped at 50 kW. We guess that the reason for that is to minimize costs on one hand and a conclusion that 50 kW for this type of cars is enough.

However, the charging curve has improved solely through the switch to a bigger battery capacity, because, as we can see, the bigger the capacity, the longer (to a higher SOC) the car was able to accept the peak value. The 22 kWh was falling at over 60% SOC, 33 kWh at around 80% SOC, while the 42 kWh was able to go up to almost 90% SOC.

Comparison of C-rate

If the charging power is similar, then clearly the packs with higher capacity will be operating in “easy” mode, at under 1.5C, compared to the original 22 kWh battery (over 2C).

A quick summary proves that the average charging power from 20% to 80% SOC improved with the increase of battery pack capacity. In the case of 2019 i3, it’s 20% higher than in 2013 i3.

DC Fast Charging Comparison by InsideEVs
Model
[data source]
Drive /
Battery
(kWh)
Max
Power
Avg
Power
(20-80%)
Max
C-Rate
Avg
C-Rate
(20-80%)
2013 BMW i3 (22 kWh)
[Fastned]
RWD
21.6 kWh
47 kW39 kW2.21.8
2017 BMW i3 (33 kWh)
[Fastned]
RWD
33.2 kWh
50 kW46 kW1.51.4
2019 BMW i3 (42 kWh)
[Fastned]
RWD
42.2 kWh
50 kW47 kW1.21.1
2020 MINI Cooper SE
[Fastned]
FWD
32.6 kWh
49 kW45 kW1.51.4

Comparison of range replenishing speed

The speed of replenishing range is not particularly high, but high enough for the purpose of city cars that probably fast charge rarely.

A quick summary also for various test cycles:

DC Fast Charging Comparison by InsideEVs
Model
[data source]
Drive /
Battery
(kWh)
Avg
Power
(20-80%)
WLTP range
rep. rate
(20-80%)
EPA range
rep. rate
(20-80%)
EPA Hgw range
rep. rate
(20-80%)
2013 BMW i3 (22 kWh)
[Fastned]
RWD
21.6 kWh
39 kWN/A4.5 km/min
(2.8 mi/min)
4.0 km/min
(2.5 mi/min)
2017 BMW i3 (33 kWh)
[Fastned]
RWD
33.2 kWh
46 kW7.2 km/min
4.5 mi/min
5.2 km/min
(3.2 mi/min)
4.6 km/min
(2.9 mi/min)
2019 BMW i3 (42 kWh)
[Fastned]
RWD
42.2 kWh
47 kW6.4 km/min
4.0 mi/min
5.0 km/min
(3.1 mi/min)
4.5 km/min
(2.8 mi/min)
2020 MINI Cooper SE
[Fastned]
FWD
32.6 kWh
45 kW6.1 km/min
3.8 mi/min
4.6 km/min
(2.9 mi/min)
4.3 km/min
(2.7 mi/min)

Conclusions

The conclusion from today’s analysis is that the new BMW i3/MINI charges faster thanks to higher battery capacity, despite the charging system being capped at 50 kW.

Here is all the data for the currently available BMW i3 and MINI Cooper SE:

2019 BMW i3 :: DC Fast Charging Summary by InsideEVs
Drive: RWD; Battery pack (net / total): 37.9 / 42.2 kWh
[Data source: Fastned]
Peak Power
Peak C-rate

Average Power (20-80% SOC)
Average-to-Peak Power
Average C-rate (20-80% SOC)

50 kW
1.2

47 kW
94%
1.1

Range Replenishing Speed (Average 20-80% SOC):
WLTP
EPA Combined
EPA Highway
6.4 km/min (4.0 mi/min)
5.0 km/min (3.1 mi/min)
4.5 km/min (2.8 mi/min)
2020 MINI Cooper SE :: DC Fast Charging Summary by InsideEVs
Drive: FWD; Battery pack (net / total): 28.9 / 32.6 kWh
[Data source: Fastned]
Peak Power
Peak C-rate

Average Power (20-80% SOC)
Average-to-Peak Power
Average C-rate (20-80% SOC)

49 kW
1.5

45 kW
92%
1.4

Range Replenishing Speed (Average 20-80% SOC):
WLTP
EPA Combined
EPA Highway
InsideEVs 70 mph
6.1 km/min (3.8 mi/min)
4.6 km/min (2.9 mi/min)
4.3 km/min (2.7 mi/min)
4.6 km/min (2.8 mi/min)

General info:

* Some values on the charts are estimated from the data source.

** Temperature of the battery cells might highly negatively affect charging capabilities. We don’t have data about temperatures of the battery at the beginning and during the charging process. In cold or hot weather, as well as after driving very dynamically, charging power might be significantly lower than shown on the charts (in extreme cases charging might be impossible until the battery temperature will not return to an acceptable level).

Source: Read Full Article