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If Electric Cars, Buses and Trucks All Use High-Power Chargers, How do Their Use Cases Differ?

(Joseph Gottlieb, CTO, Thursday, January 23, 2020)

Our blog series this month has focused on the electrification of a variety of vehicles – autos, light trucks, SUVs, and public transit buses. One common element in this story is the importance of high-power electric charging systems for these electric vehicles (EVs). But while all of these vehicles are moving toward more and more powerful chargers, the use cases for these chargers (and their requirements) differ considerably – an important point that should be considered when selecting the right charging infrastructure partner for your EV.

Consider the use case for a Tesla supercharger “refueling” a Tesla Type S EV. The power output of the Tesla Supercharger is up to 150kW; when charging the Model S (which has an 85kWh battery pack operating at 400 VDC) the Supercharger puts out 100kW, and can charge it to 100% of range in 75 minutes. In contrast, a long-range electric bus can have 8X-10X the battery capacity; for instance the Proterra Catalyst E2 max electric transit bus has a battery capacity of 660kWh with an 1250 VDC operating voltage, with an operating range of 213-290 miles. Assuming that 95% of the energy of a DC charger can be transferred to the battery, a 125kW charger would take 5 hours and 33 minutes to charge the Proterra Catalyst E2 max bus. What does this mean for charger operation? For one thing, it means that a charger for the bus is essentially running continuously, while car chargers are likely running intermittently. Moreover, the bus charger (or any charger that is charging medium/heavy duty vehicles) is stressing its components continuously, and dissipating a LOT of heat. Unless the charger is designed for these conditions, its reliability will suffer.

Rhombus Energy Solutions is an expert in the development and manufacturing of high-power bi-directional DC charging systems, with a power range from 60kW to 500kW. We apply our expertise to build chargers that thrive in continuous operation scenarios – we have shipped hundreds of high-power chargers with vehicle-to-grid capabilities to a variety of customers. Rhombus chargers are also designed from the ground up to be integrated with energy storage solutions and renewable power sources such as PV panels to minimize grid demand. Our VectorStat® software provides intelligent demand management capabilities, including peak shaving, to reduce energy costs. Rhombus looks forward to playing our part in the electrification of the transport infrastructure. Find out how we can help you by contacting us at

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