What is the VinFast VF9 Charging Time Calculator?
This tool estimates how long it will take to charge a VinFast VF9 electric SUV between any two state-of-charge levels. The VF9 ships with a large battery pack (roughly 92–123 kWh depending on trim), so charging time varies dramatically between a slow home wall box and a high-power DC fast charger. Enter your battery size, charger power, the percentage you start at, the percentage you want to reach, and a charging efficiency factor to get a realistic estimate.
How to use it
Set the battery capacity to your VF9 trim (default 123 kWh). Enter the charger power in kW — about 11 kW for a Level 2 home charger, or up to 150–250 kW at a DC fast-charge station. Pick your start and target charge levels, then choose a charging efficiency (85–95% is typical; AC charging and heat losses mean not all power reaches the battery). The result shows hours and minutes plus the kWh of energy added.
The formula explained
The calculator first finds the energy you need: \(E = \text{battery} \times (\text{target} - \text{start}) / 100\). It then divides by the effective charging power, which is the charger rating multiplied by efficiency: \(\text{Time} = E / (\text{charger} \times \text{efficiency})\). Because efficiency is below 100%, real-world charging always takes a little longer than the ideal calculation.
$$t = \dfrac{\text{Battery (kWh)} \times \dfrac{\text{Target \%} - \text{Start \%}}{100}}{\text{Charger (kW)} \times \dfrac{\text{Efficiency \%}}{100}}$$
Worked example
Charging a 123 kWh VF9 from 20% to 80% on an 11 kW home charger at 90% efficiency: energy needed = \(123 \times 0.60 = 73.8\) kWh. Effective power = \(11 \times 0.90 = 9.9\) kW. Time = \(73.8 / 9.9 \approx 7.45\) hours, or about 7h 27m.
FAQ
Why doesn't this match the manufacturer's 10–80% DC fast-charge time? DC charging tapers as the battery fills, so real fast-charge curves are non-linear. This calculator assumes constant power, which is accurate for AC home charging but optimistic for the top end of DC sessions.
What efficiency should I use? 88–92% is a good default for AC charging. DC fast charging is often slightly more efficient at the wall but limited by the taper.
Is the VF9 battery really 123 kWh? Capacity differs by trim and market; check your spec sheet and adjust the battery field accordingly.
