Mercedes-Benz EQS 450+ Charging Analysis: As Fast As Plaid?

The analysis reveals competitive results, but the peak power output above 200 kW is a bottleneck.

The Mercedes-Benz EQS is one of the latest electric cars on the market and today we will take a look at a real-world fast-charging test of the EQS 450+ version (rear-wheel drive).

The test was performed by our colleague Kyle Conner, for the Out of Spec Reviews channel, at an EVgo fast-charging station in Denver, Colorado. The charger was rated at 350 kW, but more importantly, was able to provide up to 500 A, which is important to reach high power at about 400 V.

There are two data streams – one from the charger’s display and one from the car’s display – that slightly differ. We are focusing solely on the charger’s display.

In the second part of the article, we will try to compare the results with some of the other high-end models, like the Lucid Air and Tesla Model S.

Let’s crunch some numbers!

Charging power vs state-of-charge (SOC)

According to the data obtained from the 0-100% SOC test in the video (charger’s display), charging power quickly increased to around 200 kW and remained near this level up to about one-third of the battery capacity.

The peak charging power was about 202-203 kW at about 29% SOC. Then, charging power gradually decreased to about 100 kW at 80% SOC. After that, the decrease accelerated, reaching about 40 kW before 90% SOC.

The overall shape, as well as the power level, is very similar to the charging curve shared by the manufacturer in Summer 2021.

The total energy delivered to the car (according to the EVgo charger) was 116 kWh.

State-of-charge (SOC) vs time

The charging session from 0-100% took 1 hour and 17 minutes (aside from an interruption due to the 60-minute session limit), but the more important values are:

• 10-80%: 31 minutes
• 20-80%: 27 minutes
• 10-90%: 42 minutes
• 20-90%: 39 minutes

Charging from 20% to 80% SOC took about 27 minutes and it’s not a bad result. The manufacturer promises 10-80% SOC in 31 minutes, which was achieved in the test.

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

The average power in the very important range from 20% to 80% SOC is 153 kW, which is 76% of the peak value. Between 10% and 80%, the average is 158 kW.

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

The Mercedes-Benz EQS 450+ is equipped with a 107.8 kWh battery (usable capacity). The manufacturer does not communicate the total battery capacity.

Kyle Conner guesses that the total battery capacity might be about 112 kWh, while we previously guessed 115 kWh.

The peak C-rate* – charging power in relation to the total battery capacity – is around 1.8-1.9C, depending on whether one assumes 115 kWh or 108 kWh. The average C-rate when charging from 20% to 80% SOC would be closer to 1.3C.

*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.

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

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

In the case of Mercedes-Benz EQS 450+, we have the WLTP range of about 770 km (479 miles), as well as the EPA range of 350 miles (563 km) (20″ wheels).

• WLTP
  Taking into consideration the WLTP range of 770 km (479 miles) and available battery capacity of 107.8 kWh, we can assume energy consumption of 140 Wh/km (225 Wh/mile). The effective average speed of range replenishing when charging from 20% to 80% SOC would be then 18.3 km/minute (11.3 miles/minute).
• EPA Combined range
  Taking into consideration the EPA Combined range of 350 miles (563 km) and available battery capacity of 107.8 kWh, we can assume energy consumption of 308 Wh/mile (191 Wh/km). The effective average speed of range replenishing when charging from 20% to 80% SOC would be then 8.3 miles/minute (13.3 km/minute).

The rate of range replenishing is pretty good, even for the EPA test cycle, but not as high as in the case of some other EVs.

Ultimate DC fast charging card

Here is our ultimate charging card for the Mercedes-Benz EQS 450+, which shows an estimated time of charging to add a certain number of SOC percent points, average charging power, added energy and added range for listed SOC ranges.

The matrix above, might be helpful from the user perspective, but be aware that it’s just an estimate from a particular test, with measure and calculation uncertainty probably above 5%. On top of that comes variation for individual case – car (version, age/battery state-of-health), charger, ambient and battery temperature, software version and more (including cabin heating/cooling during charging). Another thing is that the charging curve might shift when charging starts at a lower/higher SOC.

Comparisons with other EVs

Lucid Air Dream Edition

Tesla Model S Plaid (source: Tom Moloughney)

Now it’s time to compare the Mercedes-Benz EQS 450+ with the Lucid Air and Tesla Model S Plaid tests (both analyzed here):

• Lucid Air Dream Edition Range (Electrify America) – Tom Moloughney’s test (November 2022)
• Tesla Model S Plaid 21″ V3 Supercharging – Tom Moloughney’s test (October 2021)
  at 80% SOC, the session was interrupted and required a quick re-connection (see the bump on the black line), but it has a marginal influence on the result

Comparison of charging power

If we compare the Mercedes-Benz EQS 450+ with the Lucid Air Dream Edition and Tesla Model S Plaid, we will notice that there is a big difference in the power level in the first half. After 50% SOC, the three curves are more similar to each other.

One might think that the EQS charges much slower due to the difference in the first part. However, if we take a look at the average from 20 to 80% SOC, the EQS is basically on par with the Lucid Air and slightly above the Tesla Model S.

That’s a surprise, which would not be discovered without such detailed analysis.

* EQS battery capacity is usable, Tesla Model S battery capacity is just a guess

Comparison of State-of-charge (SOC) vs time

Another finding is that the charging time from 20 to 80% SOC is 27 minutes, not far behind the Tesla Model S, and 4 minutes faster than the Lucid Air.

It’s not intuitive because of the difference in the battery capacity – Lucid charges at higher power but has also more energy to recharge.

*The starting points were adjusted to the lowest common SOC.

In the 10-80% SOC window, the Tesla Model S needs 27.5 minutes, while the Lucid Air is over 34 minutes. The Mercedes-Benz EQS was in the middle between them at 31 minutes.

* EQS battery capacity is usable, Tesla Model S battery capacity is just a guess

Comparison of C-rate

The C-rate comparison confirms to us that Mercedes-Benz played it safe in the first part of the charging curve, not stressing the battery with a high charging rate.

Interestingly, it’s a little bit above the other two models between 55% SOC to over 80% SOC. The average between 20 and 80% SOC is very similar for all three.

Here are the C-Rate numbers, but remember, that we don’t know the official battery capacity of the Tesla Model S and EQS. It’s just a raw estimate.

* EQS battery capacity is usable, Tesla Model S battery capacity is just a guess

Comparison of range replenishing speed

Now, the most important metric from a consumer perspective – the range replenishing rate of the Mercedes-Benz EQS. We will use the EPA Combined range as a base (the only available common rating of the three models).

EPA range varies depending on wheel size, so we picked a few versions:

• Mercedes-Benz EQS 450+ with 20″ wheels
• Lucid Air Dream Edition Range with 19″ wheels
• Tesla Model S Long Range with 19″ wheels
• Tesla Model S Plaid with 21″ wheels

The chart reveals that the EQS is the slowest of the four:

The EQS’s average in 20-80% SOC window is 13.3 km/min (8.3 mi/min). That’s slightly less than in the case of the performance-oriented Tesla Model S Plaid, which has almost the same EPA range (348 miles) and bigger wheels.

One might ask why because the average charging power is almost as high as Lucid Air. Well, the range/efficiency in the EPA test cycle plays a role here. A comparison of the WLTP test cycle probably would be more favorable for the EQS.

* EQS battery capacity is usable, Tesla Model S battery capacity is just a guess

Conclusions

The DC fast charging test of the Mercedes-Benz EQS confirms that it’s one of the fastest charging electric cars on the market, but not as fast as the Lucid Air or Tesla Model S. The difference in range replenishing speed compared to Lucid Air is substantial.

The peak charging power of just above 200 kW is a weak point – it could be higher to improve the results.

The 400-volt battery architecture is another thing – the switch to an 800 V battery system (like in the Lucid Air or Porsche Taycan) might be a good idea.

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).

Keyword: Mercedes-Benz EQS 450+ Charging Analysis: As Fast As Plaid?