EV Charge Curve Simulator

Why Charge Curves Exist

Lithium-ion batteries accept charge much faster at low states of charge than at high. The reason is electrochemical: as the battery fills, the lithium-ion concentration gradient inside each cell flattens out and the battery management system (BMS) has to reduce current to avoid plating metallic lithium on the anode, which would permanently kill capacity. Every EV has a manufacturer-programmed curve that trades peak power for long-term battery health, and that's what you see charted here.

The 10%-to-60% Rule

On most 2024+ EVs, you add 50-60% of total battery capacity in the first 12-18 minutes of a DC fast-charging session starting at 10% SOC. The second half of the charge takes roughly twice as long for half the energy. On road trips, stopping at 10% and leaving at 60% is almost always faster-per-mile than stopping at 30% and leaving at 80%, even if you make more stops. This calculator lets you run that comparison numerically for your car.

Why 800V Matters

Cars like the Hyundai Ioniq 5, Kia EV6, Lucid Air, and Porsche Taycan run 800V battery packs. At a given power level, doubling voltage halves the current, which halves resistive heat losses (which scale with I²R). That's why 800V cars can hold near-peak power deep into the SOC range: they're producing less waste heat, so the BMS doesn't have to taper as aggressively. A 2024 Ioniq 5 can hold 235 kW from 5% to 50% SOC; most 400V cars see their peak power for only 10-15% of the curve.

What The Charger Cap Does

If your car's peak is 270 kW and the charger is 150 kW, you see 150 kW for most of the session, until the car's natural taper drops below 150 kW, after which the charger stops being the bottleneck. You can see this on the chart as the point where the green line separates from the orange dashed cap line. For 400V cars paired with 350 kW chargers, most of the session is car-limited.

Data Sources

• InsideEVs published 10-80% charging tests (2022-2025)
• Out of Spec Studios charging curves on YouTube
• Bjorn Nyland 10-80% tests
• Fastned network statistics (published charging data per model)
• Manufacturer spec sheets for battery capacity and peak kW

Curves are representative of a well-preconditioned battery at moderate ambient temperature. Cold starts without preconditioning can cut peak power by 40-60%; hot batteries on a second back-to-back session can also reduce the curve significantly (especially on passively cooled models like the Leaf and early Bolt).