It usually comes down to voltage. Most North American homes are supplied at 240 volts, while many workplaces, car parks and public sites are supplied at 208 volts. A charger draws the same current on both, but power is volts times amps, so at 208 volts the same charger delivers roughly 13 percent less power — and your car charges that much slower.
Key Takeaways
- Power is volts times amps: at 208 V a charger delivers about 13 percent less than at 240 V.
- Homes are usually 240 V; many commercial buildings are 208 V three-phase.
- The gap rarely matters overnight, but it matters for short stops and fleet planning.
- Trust the rate on the display, not the nameplate, when you compare sites.
The arithmetic
A charger’s nameplate rating is normally quoted at 240 volts. Feed it 208 volts and every figure shrinks in the same proportion:
| Circuit | At 240 V (typical home) | At 208 V (many commercial sites) |
|---|---|---|
| 32 A charger | 7.7 kW | 6.7 kW |
| 40 A charger | 9.6 kW | 8.3 kW |
| 48 A charger | 11.5 kW | 10.0 kW |
Across a long session the gap adds up. Filling a 60 kWh battery from empty at a steady 7.7 kW takes about 7.8 hours; at 6.7 kW it takes about 9 hours. Real sessions slow down near full, so treat those as simple arithmetic, not promises. Our explainer of how many kW a Level 2 charger is shows where the nameplate numbers come from.
Why buildings differ
North American homes use split-phase supply, which provides 240 volts for large loads. Larger buildings are usually served by three-phase supply, and the voltage between two phases of that supply is 208 volts. A Level 2 charger wired across two phases therefore sees 208 volts, not 240. Nothing is broken, and nobody is throttling you. The U.S. DOT describes Level 2 as a broad 7–19 kW band partly because site supply varies this way. The rate shown on the charger display or in your car is the honest number; the figure on the box was quoted for a different building.
When the gap matters, and when it does not
- Overnight and workday parking: rarely. Eight hours at 6.7 kW is about 54 kWh, more than most drivers use in a day. The car finishes either way.
- Short stops: yes. A one-hour top-up returns roughly an eighth less range, which matters at gyms, shops and meeting points.
- Fleets and shared posts: plan with the lower figure. Turnaround calculations should use the 208-volt number, not the nameplate.
- It cuts the other way at home. A charger that feels ordinary at work may be running at its full rating on your 240-volt supply.
If a charger is slower than even the 208-volt figure explains, the limit sits somewhere else: the car’s onboard charger, a current setting chosen at installation, or power being shared between posts.
Equipment for sites and homes
For shared sites, the EV-AC03201T dual-connector AC station serves two cars with OCPP 1.6J management and RFID access, so an operator can see what each post is actually delivering. At home, the EV-ACT5006T 48A wall charger reaches 11.5 kW on a 240-volt circuit; on a 208-volt feed the same unit delivers about 10 kW. That difference is the circuit talking, not the charger.
Frequently Asked Questions
Is a slower workplace charger faulty?
Usually not. If its rate is close to the 208-volt figure for its circuit size, it is working exactly as installed. A rate far below that figure is worth reporting to whoever runs the site.
Why does my portable charger show different power at home and at work?
The same reason. It draws the same amps from a lower voltage at work, so the kilowatts fall. The display is reporting the building’s supply, not a defect in the charger.
Can a site turn a charger up from 208 to 240 volts?
Not with a setting. Voltage comes from the building’s electrical service, and changing it is service work involving the utility and a licensed electrician, not an adjustment on the charger.
Related Reading
- How Many kW Is a Level 2 Charger?
- How Long Does It Take to Charge an EV at 7 kW, 11 kW and 22 kW?
- Single-Phase vs Three-Phase EV Charging: 7kW, 11kW and 22kW Explained
- 11 kW vs 22 kW Wallbox: Which Should Distributors Stock for Europe?
