Electric Vehicle (EV) automakers, such as Mercedes-Benz, Polestar, and Tesla, can use over-the-air updates to sell customers additional horsepower. It’s not unlike the Record Feedback feature that Ford will employ in most of their production vehicles this year.
But How Does Increasing a Car’s Horsepower Over The Air Work?
Since EVs are not bound to a set amount of output power like their Internal Combustion Engine (ICE) predecessors are, all it takes to increase their potential horsepower is making a few adjustments to the inverter. However, while increasing an EV’s overall power without any mechanical additions is possible, it has limits.
Currents (often called amps) are what power electric drivetrains and voltage. The latter determines motor speed in EVs, while the former creates the vehicle’s torque. So, the greater the current (or more amps) an EV has, the more motor speed it generates and the more (wattage) horsepower it creates. Since voltage in EVs remains consistent in a designated charge state, changing up its current allows EVs to increase or decrease the power they output to the wheels.
As we mentioned above, there are limits to how safely automakers can do this. Electric drivetrains have a safety limit called a continuous current rating. It ultimately comes down to how much heat a given electric drivetrain can handle. Since currents produce heat, monitoring heat levels ensures the drivetrain can manage it soundly. If the current overheats the drivetrain, an EV’s dashboard will light up like a Christmas tree, as motor1 describes it.
It’s not unlike how excessive heat can induce harmful wear and tear on an EV’s battery, reducing its ability to hold a charge efficiently.
Most of the time, automakers can increase the current. However, EV makers must consider burst currents when increasing a vehicle’s amperage. If the amperage level exceeds the continuous current rating that the drivetrain can sustain for a finite amount of time, the current’s temperature can spiral out of control. In situations like these, an EV with an advanced cooling liquid system for the inverter, motor, and battery buys the vehicle some latitude by increasing its amperage.
It all relies on automakers doing their due diligence in testing their EV’s temperature limits around current increases. Hence, they know the vehicle’s drivetrain will respond positively to an increase in amperage.
With all this in mind, automakers can efficiently increase an EV’s horsepower in an over-the-air update.
However, issues can arise with some EV drivetrains not being able to handle the extra stress that a power burst might put on crucial components such as the contactor or the connector. Figuring out which parts might experience issues with this can be challenging for carmakers.
For example, Ford miscalculated the continuous current rating on the Mach-E GT. Ford did not gauge the amperage thermal readings in the correct places on the drivetrain, which caused them to issue an unsustainable maximum horsepower limit for the Mach-E. It led to problems in the real world because the drivetrain would overheat when people floored their Mach-E for too long.
It illustrates an apparent dichotomy between EVs and ICEs. While it’s convenient to have an automaker send over-the-air updates to fix or improve a vehicle’s software or performance, as Ford does with their Record Feedback feature, physical upgrades (like the kind a veteran mechanic could perform on a vehicle’s coolant system) are still better.