When the temperature drops, so does the ability of vehicles to safely and smoothly operate. Automakers including Karma Automotive turn to winter testing facilities to assess just how much sub-zero conditions affect vehicle performance.
Karma engineers took 2020 Revero GT prototypes to Northern Minnesota to simulate and test real-life scenarios that mimic a customer living and driving in arctic temperatures. Held at the Automotive Enviro Testing facility in the city of Baudette, where temperatures are frequently the lowest in the Continental U.S., Karma’s Powertrain, Chassis, and Vehicle Integration teams ran numerous tests to gather data in multiple areas, including: component durability, energy management system, traction control calibration, powertrain, emissions and overall vehicle ride and handling.
Cold-Start Stress Tests
Conventional wisdom would dictate that you let your car warm up before driving, but engineers conducting cold-start stress testing do quite the opposite. “We start the vehicle after cold soaking overnight in -22 degrees Fahrenheit temperature and immediately drive to test the car’s engine, emissions, engine controls, battery and electronics. Cold-start testing also ensures no faults are present and misfire monitoring was calibrated properly during cold starts and catalyst heating,” says Lindsey Heineman, Karma’s Engine Controls and Emission Compliance Manager.
The team also evaluated powertrain performance using numerous road conditions including split road surfaces that consisted of asphalt on one side and ice on the other, at different grade levels. “The power and performance of the new drivetrain is completely updated,” says Tom Gacka, Powertrain a**lysis Manager. “Every powertrain component in the Revero GT is brand new including the engine, generator, battery, and rear drive module (gearbox, motors and inverters). We have two completely independent drive systems that allow flexibility on how the Revero GT distributes torque. It can react to changing road conditions faster with a quicker response time.”
“The advantage is huge in terms of vehicle handling and traction and the main reason why we chose this type of architecture and brand new drive rear –wheel drive module program for our Revero GT.” Gacka also mentioned, “We completed all the required testing for powertrain, and the end results were incredibly successful.”
“When testing cars in Baudette, it can be extremely cold and component limitations are challenging in climactic weather,” says Heineman. In order to maintain maximum vehicle range and performance, it’s important that battery cells maintain stabilized temperatures at all times. Cold weather can also cause a slower charging rate. “When the battery is cold, charge and discharge limits are very small so there’s a lot of drivability calibrations our engineers implement to make sure the vehicle maintains a smooth propulsion. In testing the Revero GT battery state of charge (SOC) in the cold conditions, we outfitted our power pack with hundreds of thermal couples to monitor state of health, charge, and power to validate the thermal system,” says Heineman.
Pushing the limits
So what does all this validation mean in terms of the driving experience? Not only does it help us deliver class-leading all-electric range with our Revero GT, it also means using the latest electronic traction and technology to help ensure driver safety and user confidence for an unparalleled driving experience. If you’d like to validate that claim for yourself (in less extreme conditions), stay tuned to Karma Community and our social channels as we deliver news about the Revero GT coming to a location near you.