What does Ramp-Up mean?

Explanation

When you plug into a DC fast charger, the power does not instantly jump to maximum. Instead, the charger and car communicate to negotiate a safe power level, then the car gradually increases the amount of power it draws. This initial climb from near zero to peak power is called the ramp-up phase.

Ramp-up typically takes 1-5 minutes depending on the car and conditions. If your battery is cold, the ramp-up may be slower because the battery management system limits power until the cells warm up. Some cars, like the Tesla Model 3 with preconditioning enabled, reach peak power very quickly. Others take several minutes.

You can watch the ramp-up happen on the charger screen. The kW number will climb steadily from something like 20 kW up toward the car's peak power. If your battery is preconditioned and at a low SoC, the ramp-up is usually fast. If the battery is cold or nearly full, you might see a slow, limited ramp that never reaches the car's advertised peak.

For official definitions, visit National Renewable Energy Laboratory.

Where you'll see this

• On the charger screen
• On your car dashboard

Common confusion

Some drivers unplug and replug if they see low initial power, thinking the charger is faulty. In most cases, the car simply needs a minute or two to ramp up. Wait a few minutes before troubleshooting.

Example

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