Twenty-four percent of opportunity charging sessions start when the battery is already more than 80% charged, according to a report released by ViriCiti, a provider of electric fleet and infrastructure management solutions.

ViriCiti connects to more than 1,200 charger sockets (plugin & pantograph) across the world and has registered almost 3 million charging transactions from more than 1,000 vehicles since 2018. For the report, ViriCiti analyzed 40,000 charging sessions from ~190 charging stations in the US and EU.

Here, ViriCiti defines “opportunity charging” as charging sessions happening during regular service hours (5am-11pm) when most operators have their regular bus schedules, with a duration of maximum 60 minutes, and done through on-route chargers with a minimum power of 100 kW.

Charging power decreases as battery state-of-charge (SoC) increases—with a sharp inflection point at around 80% SoC. This well-known phenomenon happens because the BMS (Battery Management System) reduces the charging power to avoid overheating the battery cells. This also means that those 24% of opportunity charging sessions don’t use the fast chargers at their full capacity.

Source: ViriCiti

Furthermore, the report shows that the average duration of an opportunity charging session is close to 26 minutes, with an average energy charged of 69.8 kWh. Operators also seem to start charging their buses on-route at an already high SoC level averaging at approximately 64%.

The results also indicate that there is room for a more efficient driving of electric buses, which would mean lower starting SoC and faster charging rates, leading to shorter charging sessions and better on-route recovery.

Intelligent telematics systems such as ViriCiti’s help operators use existing charging infrastructure more efficiently, prioritizing chargers based on itinerary, lowering demand costs through peak shaving, and decreasing energy costs by shifting charging times to lower energy tariffs.