What does Taper mean?

Explanation

Taper refers to the way your car reduces the charging power it accepts as the battery approaches full. Imagine filling a glass of water: you pour fast when it is empty, but slow down near the top to avoid spilling. Your car does the same thing to protect the battery cells from damage caused by high power at high charge levels.

You will notice taper by watching the kW reading on the charger screen drop as your SoC climbs. A car might start at 150 kW at 20%, drop to 100 kW at 60%, then slow to 40 kW at 80%, and crawl at 10-15 kW above 90%. This is why charging from 80% to 100% can take as long as charging from 10% to 80%.

Understanding taper is the key to efficient road trip charging. The sweet spot for most EVs is charging from about 10-20% to 70-80%, then driving on. You spend less total time charging by making more short stops rather than fewer long ones, because each minute spent above 80% delivers very little additional range.

Where you'll see this

• On the charger screen
• On your car dashboard

Common confusion

Drivers sometimes think their charger is broken when power drops at high SoC. It is not the charger. It is your car deliberately limiting the power to protect the battery.

Example

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