3.3kW vs 6.6kW vs 11kW OBC: Which One Do You Need?
Compare 3.3kW, 6.6kW and 11kW onboard chargers for commercial EVs — charging time, battery size, AC supply, and how to choose the right power. Read more.
Selection Checklist
- ☐ Daily energy use (kWh) and charging window (hours) are written down.
- ☐ Required power is calculated as daily energy ÷ window, with 10-20% taper margin.
- ☐ AC supply — voltage, phases, and continuous current — is confirmed.
- ☐ Battery voltage platform is matched to the OBC output range.
- ☐ Power at 110 Vac vs 220 Vac is checked for the specific model.
- ☐ Space, weight, cooling, and mounting are checked for the chosen power.
- ☐ DC-DC power is checked separately, especially for 2-in-1 units.
- ☐ Future route or shift changes that could shorten the window are noted.
Related reading: How to Choose an On-Board Charger (OBC) for Commercial EVs · OBC + DC-DC Integration: When Does a 2-in-1 Make Sense? · OBC RFQ Checklist: What EV Manufacturers Should Provide Before Requesting a Quotation
FAQ
Is 6.6 kW always twice as fast as 3.3 kW?
In the simple formula, yes — about 6.5 hours versus 13.0 hours for a 40 kWh pack. In practice, both are limited by the CC-CV taper near full charge and by the BMS current limit, so the ratio is approximate.
Can I use an 11 kW OBC on single-phase AC?
Usually not at full power. 11 kW normally needs three-phase AC. Confirm the input requirement, connector, and whether the unit derates on single-phase before specifying it.
Does a bigger OBC damage the battery?
Not if the BMS controls the charge. The OBC follows the BMS current and voltage limits. A larger unit does not force more current into the battery than the BMS allows.
What if my depot only has 110 Vac?
Then a 6.6 kW OBC will deliver about 3,300 W in the Echelon example. Size the system on the power at the actual AC voltage, not on the headline rating.
Should I choose 6.6 kW just to be safe?
Only if the duty cycle may grow. If the daily energy and window are stable and 3.3 kW fits with margin, the smaller unit saves space, weight, and cost.
Related Echelon Products
See the full range on the products page.
Next Step
Calculate your daily energy and charging window, then request a datasheet and RFQ from the Echelon engineering team for the power level that fits — 3.3 kW or 6.6 kW in the confirmed range — and confirm 11 kW availability separately if your duty cycle needs it.
To start, share your vehicle and battery requirements through our contact page, and see how a custom programme is scoped on our OEM/ODM page. Before requesting a quotation, the OBC RFQ checklist lists the inputs that let Echelon quote accurately in one pass.
About Echelon Charger
Echelon Energy Technology specializes in onboard chargers, DC/DC converters, and integrated EV power solutions for commercial and specialty electric vehicles.
For technical discussions, product selection, or OEM/ODM cooperation:
Email: nancy@tici-energy.com
WhatsApp: +86 18114665311
