Why your car charges slower at 80% — and why that is correct behaviour

Drivers new to EVs often report the same thing: the charger promised 180 kW, the car pulled 140 kW for a while, then dropped to 40 kW. Nothing is broken. This is the charging curve, and every lithium-ion pack has one.

What limits the rate

Charging speed is set by how fast lithium ions can move into the anode without plating out as metallic lithium. That rate depends on how full the anode already is, and on temperature. As the cell fills, the battery management system reduces current to stay safely inside the envelope. Push past it and you permanently lose capacity.

The shape of a typical curve

On a modern 400V CCS2 car: near-peak power from 10% to about 45%, a first step down around 50%, a steeper taper from 65%, and by 80% you are typically at a third of peak. From 80% to 100% often takes as long as 10% to 80% did.

Temperature matters as much as state of charge

A cold pack charges slowly regardless of how empty it is. Cars with active thermal management precondition the battery when you navigate to a charger — which is why using in-car navigation to a station genuinely produces a faster session. On a hot Rajasthan afternoon the opposite applies: the pack may throttle to shed heat.

What this means in practice

Plan around 10–80%, not 0–100%. Two shorter stops beat one long one on a highway drive. And if you need 100% — because the next leg is long — do it overnight on an AC bay, where the taper costs you nothing.

Reading the bay rating correctly

A 180 kW bay is a ceiling, not a promise. Your car takes what its own curve allows. A car limited to 90 kW gains nothing from a 180 kW dispenser except a shorter queue.