Charging from 20% to 80% means adding 60% of the battery, and with the EV-ACS4005T the time depends on your pack size and the current step you select. For a 60 kWh battery that is 36 kWh: about 4 to 4.5 hours at the full 40 A setting (9.6 kW), allowing roughly a tenth for losses. Smaller packs finish sooner, larger packs take proportionally longer.
Key Takeaways
- The 20–80 window adds 60% of the battery; time is that energy divided by power, plus about 10%.
- At 40 A, a 60 kWh pack takes about 4 to 4.5 hours; a 100 kWh pack about 6.5 to 7.
- Lower settings stretch the window in proportion — 16 A roughly triples the 40 A time.
- The car’s onboard AC limit can override every setting; check it before the charger.
The Arithmetic of the 20–80 Window
The formula is the same one behind our general guide to how long it takes to charge an EV at 7 kW, 11 kW and 22 kW: energy to add, divided by charging power, plus about 10% for conversion losses. The 20–80 window is the fast part of the battery — it skips the slowest top end, which is why charging slows down after 80% and why drivers plan around this window. All figures below are worked examples at 240 V, not ratings.
| Battery size | Energy for 20–80% | At 40 A (9.6 kW) | At 32 A (about 7.7 kW) |
|---|---|---|---|
| 40 kWh | 24 kWh | About 2.5–3 hours | About 3–3.5 hours |
| 60 kWh | 36 kWh | About 4–4.5 hours | About 5–5.5 hours |
| 75 kWh | 45 kWh | About 5–5.5 hours | About 6–6.5 hours |
| 100 kWh | 60 kWh | About 6.5–7 hours | About 8–8.5 hours |
The Lower Settings Stretch the Same Window
The two lower steps exist for smaller circuits, and they stretch the same window in proportion. At 24 A (about 5.8 kW), the 60 kWh example needs roughly 7 hours; at 16 A (about 3.8 kW), roughly 10.5 hours — still an overnight session, but with little margin. Which step you may use is decided by the circuit, not by preference: our guide to how many amps an EV charger needs explains the pairing. On a 50 A circuit, run the full 40 A and take the fastest column.
The Car Can Still Be the Limit
These times assume the car accepts everything the charger offers. With AC charging, the car’s onboard charger does the conversion and sets the ceiling: a car limited to 7.4 kW of single-phase AC will charge at 7.4 kW no matter which step you select, and the 60 kWh example stretches to about 5.5 hours. A cold battery also starts more slowly until it warms. Check your car’s AC charging specification alongside its battery size before blaming the charger for a long session — the same weakest-link logic explains most cases of an EV charging slowly at home.
The EV-ACS4005T sits in the U.S. DOT’s Level 2 band of 7–19 kW at its top two settings, and its four steps let one unit serve circuits from 20 A to 50 A. For the 20–80 routine most drivers actually run, the practical answer is simple: on a 50 A circuit, even a 100 kWh pack finishes the window inside a normal night.
Frequently Asked Questions
Why do drivers quote 20% to 80% instead of a full charge?
Because the top of the battery charges slowest and the bottom is rarely reached in daily use. The 20–80 window is the part of the pack drivers actually cycle, so its time is the useful planning number.
Does a bigger battery always take longer in this window?
Yes, in proportion. The window is always 60% of the pack, so a 100 kWh battery needs two and a half times the energy — and roughly two and a half times the hours — of a 40 kWh battery at the same setting.
What if my car only accepts 7.4 kW on AC?
Then the car sets the pace at every setting. Use the 32 A column as your closest guide, and expect the 60 kWh example to take about 5.5 hours instead of 4 to 4.5.
Related Reading
- How Long Does It Take to Charge an EV at 7 kW, 11 kW and 22 kW?
- Why Does EV Charging Slow Down After 80%?
- How Many Amps Does an EV Charger Need?
- Why Is My Electric Car Charging Slowly at Home?
