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BMW iX3 DC Fast Charging Analysis: 150+ kW Peak, Decent Curve

But can it beat Audi e-tron or Mercedes-Benz EQC?

BMW iX3 (2020)

Mark Kane

By: Mark Kane

Apr 18, 2021 at 1:18pm ET

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Today we will get into the DC fast charging performance of the BMW iX3 - a new all-electric SUV that is produced in China for the Chinese and European markets (unfortunately there is no U.S. version)

The first version of the BMW iX3 is equipped with a 80 kWh battery for WLTP range of 450-458 km (280-285 miles) and 210 kW electric motor. BMW says that charging to 80% takes about 34 minutes.

The data for this particular analysis comes from Fastned, one of the leading European fast-charging networks, which from time to time evaluates new EVs and releases their charging curve.

Hopefully, this article will tell us also how well the BMW iX3 stands against the Audi e-tron and Mercedes-Benz EQC.

Charging power vs state-of-charge (SOC)

The fast charging of BMW iX3 starts at a strong level of around 150 kW and peaks at nearly 157 kW. The level of close to 150 kW is maintained up to about 25% SOC.

The curve has multiple shorter or longer steps of power decrease. As you can see, the final straight before the end, is at almost 50 kW (between 80-95%). Really not bad.

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State-of-charge (SOC) vs time

BMW expects that 80% recharge (we assume 0-80%) should take about 34 minutes. We estimate that in the case of this particular session, it was exactly the case (20-80% was probably 29 minutes).

Average charging power vs state-of-charge (SOC)

The average power in the very important range from 20% to 80% SOC is about 91 kW, which is 58% of the peak value.

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C-rate vs state-of-charge (SOC)

The peak C-rate* - charging power in relation to the total battery capacity of 80 kWh - is almost 2.0C. That's one of the highest levels.

The average C-rate when charging from 20% to 80% SOC is over 1.1C. This is more in line with the average in the industry.

*C-rate tells us how the charging power relates to the battery pack capacity. For example: 1C is 1-hour charging power (current), when the power value in kW is equal to the battery pack capacity in kWh. 2C would be enough to recharge in half an hour.

The net battery capacity of 74 kWh stands for about 93% of the total battery capacity.

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Range replenishing speed vs state-of-charge (SOC)

The rate of replenishing range depends on the energy consumption and the energy consumption depends on the use case.

In the case of BMW iX3 we only have data for the WLTP cycle:

WLTP
Taking into consideration the WLTP range of 458 km (285 miles) and available battery capacity of 74 kWh, we can assume energy consumption of 162 Wh/km (260 Wh/mile).
The effective average speed of range replenishing when charging from 20% to 80% SOC would be then 9.4 km/minute (5.8 miles/minute).

The rate of range replenishing is really strong, nothing to complain about:

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Comparisons with other EVs

2019 Audi E-Tron

Mercedes-Benz EQC 400 4MATIC

Mercedes-Benz EQC

Comparison of charging power

Now let's take a look at the BMW iX3 in comparison with two other German EVs: the outstanding Audi e-tron, which is well known for its great charging curve, and the Mercedes-Benz EQC.

Both of those cars have bigger batteries. The 2019 e-tron is equipped with a 95 kWh battery (83.6 kWh was usable at that time, increased to 86.5 kWh in new model year versions), while the EQC has a 85 kWh battery, and about 80 kWh is usable.

Despite the smaller battery pack, the iX3 does quite well. Initially, it outpaces the e-tron, then maintains its rate up to 30% SOC, before the decrease starts (the e-tron amazes with constant 150 kW rate up to 80%). The iX3 is no match for the EQC up to 50% SOC or so, and then it's slightly below EQC.

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Comparison of C-rate

Because of the smaller battery than the e-tron and EQC, the iX3 actually delivers a strong C-rate. There is no match for the iX3 in the first part, and then it basically matches the EQC (the e-tron has much better 50-100% part).

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Comparison of range replenishing speed

All of the individual tests and calculations culminates when we compare the range replenishing speed - in this case for the WLTP range number.

As you can see, the BMW iX3 amazes in the beginning with an outstanding 15 km/minute (9.3 miles/minute) up to almost 30% SOC!

Because the iX3 uses less energy than the Audi e-tron, it basically replenishes range faster or as fast as the e-tron up to about 45% SOC. The Mercedes-Benz EQC is far behind, under 10 km/minute (6.2 miles/minute).

In the second half of the battery capacity, the BMW iX3 and Mercedes-Benz EQC appears to replenish range at a similar rate, while the Audi e-tron glides above them.

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If all three show such different curves, which is actually better? Well, maybe we will stick to the average from 20 to 80% SOC.

Then the average power and WLTP range replenishing rate of the BMW iX3 is better than the Mercedes-Benz EQC by 10%, but 24% slower than Audi e-tron:

DC Fast Charging Comparison Model
[data source] Drive /
Battery
(kWh) Max
Power Avg
Power
(20-80%) Max
C-Rate Avg
C-Rate
(20-80%) WLTP range
rep. rate
(20-80%) 2019 Audi e-tron quattro 55 SUV
[Fastned] AWD
95 kWh 155 kW 149 kW 1.6 1.6 12.4 km/min
7.7 mi/min 2021 BMW iX3 (80 kWh RWD)
[Fastned] RWD
80 kWh 157 kW 91 kW 2 1.1 9.4 km/min
5.8 mi/min 2019 Mercedes EQC 400
[Fastned] AWD
85 kWh 113 kW 98 kW 1.3 1.2 8.5 km/min
5.3 mi/min

Conclusions

The conclusion from the DC fast charging test of the 2021 BMW iX3 is positive. The charging power and curve are quite strong, especially at the lower SOC levels.

The average rate of range replenishing of about 9.4 km/minute (5.8 miles/minute) is good, but not better than in the case of Audi e-tron.

2021 BMW iX3 :: DC Fast Charging Summary by InsideEVs
Drive: RWD; Battery pack (net / total): 74 / 80 kWh
[Data source: Fastned] Peak Power
Peak C-rate

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

Time (20-80% SOC) 157 kW
2.0

91 kW
58%
1.1

around half an hour Range Replenishing Speed (Average 20-80% SOC): WLTP 9.4 km/min (5.8 mi/min)