One of the biggest challenges with charging electric vehicles, especially heavy duty and transit vehicles, is handling extreme weather. In the North American market this is most often an issue with winter charging. The science behind this is fairly well understood; cold weather reduces vehicle range by as much as 40%.

There are additional problems in the cold with driver behavior. The drivers heat up the bus before they start to drive, which can drain the battery further if drawing from battery energy. Driving conditions can also reduce the efficiency of the regenerative braking. For some vehicles, it is recommended that regen is turned off to avoid loss of traction in icy conditions, further impairing the range a driver or fleet owner would usually expect from the vehicle.

Product Management Challenge

From a charging software perspective, we understood the problem, and now needed a solution. The parameters of the solution are that it had to be automatic and seasonally adjusted. We went to work for a couple of public school fleets that desperately needed the help, as their vehicles were having trouble even making it back to the charging depot. We designed a charging automation where we could optimize vehicle overnight charging so that the session would end right when the bus was scheduled to leave. It took months of testing and work with the bus manufacturer and bus dealers who were the boots on the ground, providing critical support.

Now getting there was tricky and took lots of experimentation. Some approaches we thought were clever become impossible to get right in practice without a huge investment in data scientists to help make best guesses. A solution parameter we learned about later was that changes to the vehicle and powertrain were not possible in a timely fashion, for good reason. The vehicle manufacturers all want to ship a solid product, and messing with basic settings around charging and battery conditioning introduces risk to a production vehicle. There are also significant regulatory requirements, especially around school buses (thank goodness, since my kids take a bus to school). Charging software can be more nimble and experimental without endangering vehicle or charger safety certifications.

This automation, when it finally worked as expected, solved the three problems neatly. First, the battery was at an optimal temperature at departure time, and the heating had come from the grid. Second, the vehicle's internal components were warm so the regenerative braking was not impaired by ice or slush. Third, the driver could turn the heat on and also draw from the grid, preserving battery life.