Nissan LEAF Might Have A Good Fast Charging Curve With Active TMS
Let’s take a look at a very special DC fast charging test and see the results that you will probably never repeat.
The Nissan LEAF was one of the first electric cars with lithium-ion batteries on the market. Overall, it was a good electric car, but with a major weak point – the lack of an active battery thermal management system (TMS).
Despite that, the company has improved the car over the years, with higher battery capacity (24 kWh, 30 kWh, 40 kWh and 62 kWh), higher onboard charging power, and a higher power electric motor/power electronics. However, the lack of active TMS has remained the fundamental flaw of the LEAF. We can only guess that the company wanted to save costs.
As a result, the LEAF never had a chance to fully show its potential. The longevity of the battery pack was affected (especially in hot climates) and the charge/discharge performance was significantly reduced in both hot and cold climates. It would not be as big an issue for a city car, but the LEAF was targeted as a replacement for the primary car.
Today we will analyze a little bit deeper our previous DC fast charging test of the 2020 Nissan LEAF Plus (62 kWh) SL from October 2020, as it’s a very specific case that shows what the LEAF could actually deliver if it was equipped with a liquid cooling battery system.
The car arrived at the charging station with basically 0% State of Charge (SOC) and low battery temperature. Moreover, the CHAdeMO charger rated at 50 kW, was able to provide close to 70 kW. Those higher power CHAdeMO chargers are not common.
This test might then be considered as the best-case scenario. We assume that typically users will not arrive with low battery temperature, especially after driving for some time, and the power output will be limited.
Charging power vs state-of-charge (SOC)
The 2020 Nissan LEAF Plus SL was able to achieve a peak charging power of about 69 kW. The shape of the charging curve is surprisingly good, compared to what we usually see when charging LEAFs.
Charging from 20% to 80% SOC took about 35 minutes. Not a bad result to replenish about 218 km (136 miles of range).
Average charging power vs state-of-charge (SOC)
The average power in the very important range from 20% to 80% SOC is 54 kW, which is 78% of the peak value.
C-rate vs state-of-charge (SOC)
The peak C-rate* – charging power in relation to the total battery capacity of 62 kWh is about 1.1C.
The average C-rate when charging from 20% to 80% SOC is 0.86C.
*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.
We guess that the net battery capacity is around 56 kWh, which would be about 90% of the total battery capacity.
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.
Applying range results for different test cycles, including our very own IEVs 70 mph range test, we can draw range replenishing speed vs state-of-charge (SOC):
- WLTP range
Taking into consideration the WLTP range of 385 km (239 miles) and available battery capacity of 56 kWh, we can assume energy consumption of 145 Wh/km (234 Wh/mile).
The effective average speed of range replenishing when charging from 20% to 80% SOC would be 6.1 km/minute (3.8 miles/minute).
- EPA Combined range
Taking into consideration the EPA Combined range of 215 miles (346 km) and available battery capacity of 56 kWh, we can assume energy consumption of 260 Wh/mile (162 Wh/km).
The effective average speed of range replenishing when charging from 20% to 80% SOC would be 3.4 miles/minute (5.5 km/minute).
- EPA Highway range
Taking into consideration the EPA Highway range of 192.5 miles (310 km) and available battery capacity of 56 kWh, we can assume energy consumption of 291 Wh/mile (181 Wh/km).
The effective average speed of range replenishing when charging from 20% to 80% SOC would be 3.1 miles/minute (4.9 km/minute).
- IEVs 70 mph range test
Taking into consideration the IEVs 70 mph range test result of 193.6 miles (312 km) and available battery capacity of 56 kWh, we can assume energy consumption of 289 Wh/mile (180 Wh/km).
The effective average speed of range replenishing when charging from 20% to 80% SOC would be 3.1 miles/minute (5 km/minute).
The conclusion of this test is that Nissan missed an opportunity to make the LEAF a great car for longer journeys and for use in higher temperatures. No one would probably complain about the charging curve like that if it would be easily achievable.
But it’s not easily achievable. Kyle Conner reports that he first skipped conducting the test because the car arrived at high battery temperature. And in the completed test, described above, the car went into power reduction mode after leaving the charging station.
* 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).
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