What Does a Medium/Heavy Duty Electric Vehicle Need From Its Charging Infrastructure

(Joseph Gottlieb, CTO, Tuesday October 6, 2020)

One of the vehicle segments that has been taking off from an electrification standpoint is medium/heavy duty (M/HD) electric vehicles (EVs). Transit buses in particular are being electrified at a very high rate. However, charging M/HD EVs is far more complex than charging electric automobiles.  M/HD EVs tend to have battery capacities significantly greater than that of other EVs – capacities can range from 150kWh to over 600kWh. A typical home charger for an electric auto might have a power output of 10kW, which can charge a car like a Chevy Bolt (60kWh battery capacity) in 6 hours. The same charger would require 15 hours to charge an M/HD EV with a 150kWh capacity, and 60 hours to charge one with a 600kWh battery capacity. Since M/HD EVs are almost always work vehicles, charging typically the charging window would be between 9pm and 5am (8 hours). This would require a charger with a capacity between 20kW (for a 150kWh vehicle) and 75kW (for a 600kWh vehicle).

This is only the first complexity. Since M/HD EVs are work vehicles, the chargers that support them also needs to be highly reliable. If the charger for your car breaks, you might have to take the bus, taxi, or a ridesharing service to work and back that day. You might even be able to buy a new charger at a local hardware store. An out-of-service charger for a M/HD EV is a little different – they are the size of a refrigerator, and cost tens of thousands of dollars. A broken M/HD charger requires a skilled maintenance technician, which can take several days to dispatch. The cost of the downed M/HD EV can easily be thousands of dollars. To minimize the likelihood of this, M/HD EV chargers must be designed for both high reliability and ease of maintenance,

Rhombus has built high-power inverters for renewable energy such as “behind the meter” grid energy storage systems for several years. We have applied that expertise to the design of our latest-generation bi-directional electric vehicle (EV) charging systems (which are designed from the start for the needs of fleet operators) and bi-directional smart inverter systems for microgrids. Rhombus expertise in energy management system (EMS) software is also embedded in our VectorStat EMS controller and software which is embedded in our EV charging systems and smart inverters. Rhombus also excels in the design and testing of high-power electrical equipment to meet the requirements of UL and other certification organizations. We have built hundreds of V2G-capable high-power, high-reliability chargers and bi-directional smart inverters for a variety of different sizes and classes of EVs. Find out how we can help you by contacting us at sales@rhombusenergy.com, or by reading our Vehicle to Grid Solution Brief.