Why does charging slow down after 80%?

This is called the 'Charging Curve.' As the battery gets full, the car's software slows down the intake of energy to prevent overheating and cell damage. The last 20% often takes as long as the first 80%.

Is it bad to charge to 100%?

For daily driving, yes. Keeping a battery at 100% degrades it faster. However, for road trips, charging to 100% just before you leave is perfectly fine. LFP batteries (like in base Model 3s) can be charged to 100% regularly.

EV Charging Time Calculator

Estimate how long it will take to charge your EV battery.

🔋 Battery Status

Battery Capacity (kWh):

e.g., Model Y (75), Bolt (65)

Current (%):

Target (%):

🔌 Charger Type

Charger Power:

Custom Power (kW):

Efficiency Loss (%):

~10% is standard energy loss.

The "Always Be Charging" Rule

With an EV, you shouldn't think like a gas car owner ("fill up only when empty"). The goal is to maximize your "dwell time"—charging while you are parked anyway (sleeping, working, shopping).

Level 1 (Trickle)

Plugging into a standard wall outlet adds about 3-5 miles per hour. It's slow, but over a 12-hour overnight stay, that's 40-60 miles—enough for most daily commutes.

Level 3 (Fast Charging)

Used for road trips. Speed is not linear. You get the fastest speeds between 10% and 50% SOC (State of Charge). Arriving at a charger with 10% is faster than arriving with 40%.

The 80% Road Trip Strategy

On long trips, you save time by stopping more often but for shorter periods. Charging from 10% to 80% might take 20 minutes. Charging from 80% to 100% might take another 30 minutes!
Rule: Unplug and leave as soon as you have enough range to reach the next charger + 10% buffer.