When it comes to benchmarking a new electric car for a road test, there’s one crucial step that often reveals a lot about the vehicle’s performance: draining the battery. While not formally part of the test process, this step is essential for understanding the true capabilities of an EV.
Starting with a minimum 90% charge, our testing typically involves acceleration, braking, handling tests, and more, gradually depleting the battery to between 45% and 65% state of charge (SoC). At this point, two key tests remain: measuring acceleration at less than 10% SoC and conducting DC rapid-charge testing.
So, how do we quickly drain an EV’s battery to simulate real-world conditions? As an Autocar road tester, the preferred method involves pushing the vehicle to its limits on a track. One tactic is to drive aggressively on a circuit like the Horiba MIRA proving ground’s ‘number one’ circuit, pushing the car to high speeds and cornering forces.
By accelerating hard, braking forcefully, and cornering aggressively, the battery is rapidly depleted, testing the powertrain’s cooling system and overall performance. While this intense driving may cause some EVs to limit motor output or enter a limp mode to cool down, it’s a necessary step to understand the car’s capabilities under extreme conditions.
Interestingly, some EVs lack a battery temperature gauge, which could provide valuable information about the battery’s health and performance during high-demand situations. Having a feature to quickly drain the battery to a specific SoC level could also be beneficial for testing purposes, although it may not be practical or safe for everyday use.
In the end, pushing an EV to its limits on the track is a valuable part of the testing process, providing insights into performance, battery management, and overall durability. While most owners won’t drive their EVs as aggressively as a road tester, understanding how the vehicle performs under extreme conditions is essential for evaluating its true capabilities.
