AC vs DC EV charging for commercial sites: choose by vehicle and dwell time

Choose AC when compatible vehicles have enough parking time to receive the required energy; consider DC when the charging window or vehicle duty requires it. Higher charger power is useful only if the vehicle, connector and available supply can use it. A 22 kW AC point does not make a car with a 7 kW on-board charging limit take 22 kW.

AC charging supplies the vehicle's on-board charger; DC equipment performs the conversion outside the vehicle. This distinction is explained in the NITI Aayog EV charging infrastructure handbook. Use that principle with the current vehicle manual and exact EVSE datasheet, rather than treating a generic connector label as proof of compatibility.

Start with the parking task

Use charging-time examples correctly

Suppose a car needs 21 kWh added to its battery before departure. If the charger and car together permit 7 kW AC input and the assumed overall AC-to-battery efficiency is 90%, the arithmetic is 21 ÷ (7 × 0.90) = 3.33 hours. On a 22 kW AC point, the same 7 kW-limited car still needs approximately that time. The 90% figure is an illustrative assumption, not a specification or guaranteed session time.

For DC, suppose the required battery energy is 30 kWh and the vehicle sustains an average 40 kW at the battery over the selected window. The energy-only estimate is 30 ÷ 40 = 0.75 hours, or 45 minutes. Do not divide by a peak 60 kW nameplate if the vehicle's charging curve averages less. Arrival state of charge, temperature, preconditioning, battery limits and session overhead can change the result.

Separate DC output from building input

A hypothetical charger delivering 60 kW DC at 95% conversion efficiency draws about 63.2 kW before any separately specified auxiliary loads. At an assumed input power factor of 0.99, that is approximately 63.8 kVA. Actual design uses the manufacturer's maximum input data, including its operating conditions. kW is real power; kVA is apparent power; kWh is energy delivered or consumed over time.

Check the cabinet's total output as well as each outlet's limit. Power may be shared between vehicles, and some products can share capacity across compatible cabinets. Exicom's power-sharing explanation is one manufacturer example, not a claim that every charger has that capability. Ask the bidder to show the simultaneous-output table for the exact configuration.

Ask for a compatibility schedule before ordering

• Vehicle model and model year, AC phase/current limit, DC voltage/current envelope and inlet.
• EVSE model, connector, output range, cable reach and permitted installation environment.
• Number of vehicles charging together and the allocated power when all outlets are occupied.
• Load-management behaviour during network failure and recovery after a power interruption.
• Demonstrated charging with representative vehicles at site acceptance.

The EV charging load calculator is a screening tool. Final selection needs the electrical study, operating schedule and supplier's data. Do not buy DC purely because it appears more future-proof: reserve expansion routes and capacity on evidence, then install the useful first phase.

Request an EV site assessment Share the site location and your requirement with Secured Engineers. Electrical infrastructure, charger supply, software and ongoing support responsibilities are agreed in the project scope.

Continue planning your installation

• Build a depot charging schedule around dispatch
• Set workplace and hotel access rules

Sources checked 7 November 2026. Confirm the applicable order, equipment revision and site conditions before procurement.