Fleet charging time comes down to one equation: energy needed divided by charging power. A vehicle that needs 70 kWh takes about seven hours at 10 kW and about 28 minutes at 150 kW, at best. Those two numbers decide how many chargers a depot needs, how much power to request from the utility, and how many vehicles can go back to work each shift. This guide shows the math, a table by charger level, and what changes in real fleet operations.
How do you calculate fleet charging time?
Use this formula:
Charging time (hours) = energy to add (kWh) ÷ charging power (kW)
Energy to add is battery size times the share you need to refill. A 70 kWh battery that goes from 20% to 80% needs about 42 kWh. A full 0 to 100% refill is 70 kWh. The figures below use 70 kWh as an illustration only; your vehicles will differ.
How long does a 70 kWh battery take at each charging power?
| Charging power | Typical use | Full 70 kWh, best case | 42 kWh (20% to 80%), best case |
|---|---|---|---|
| 7 kW | Slow AC (Level 2) | 10 hours | 6 hours |
| 11 kW | Mid AC (Level 2) | 6 h 22 min | 3 h 49 min |
| 19 kW | High-power AC (Level 2) | 3 h 41 min | 2 h 13 min |
| 10 kW | Wireless, as claimed by one vendor [1] | 7 hours | 4 h 12 min |
| 50 kW | DC fast | 1 h 24 min | 50 min |
| 150 kW | High-power DC fast | 28 min | 17 min |
| 350 kW | Ultra-fast DC | 12 min | 7 min |
These are constant-power, best-case numbers. They ignore charging losses, taper as the battery fills, cold weather and battery condition. They also assume the vehicle can accept that much power. A vehicle's own onboard charger can cap AC speed, and its battery limits DC speed. For reference, the U.S. Department of Energy says Level 2 charging adds roughly 25 miles of range per hour.[2]
Why does dwell time matter more than the charger label?
Dwell time is how long a vehicle sits available to charge. A delivery van that parks for 10 hours overnight can use slow AC charging and still be full by morning. A vehicle that must be back on the road in 20 minutes cannot. The right question is not "which charger is best" but "how many kWh does each vehicle need in the time it is parked."
Start with each vehicle's daily energy use, not battery size. A van that uses 45 kWh per day does not need a 70 kWh refill. Then compare that to the energy a charger can deliver during the dwell window.
How much power does a depot need?
Total site demand is the number of vehicles charging at once times the power of each charger. Fifty vehicles on 11 kW chargers, all charging together, draw about 550 kW. If you stagger them in two waves with load management, the peak falls to about 275 kW, at the cost of a longer overall charging window. Utility capacity and upgrade timelines often set the schedule more than the charger order does.
Our guide to fleet depot charging covers why power, not vehicles, often sets the pace.
Does wireless charging change fleet charging time?
Charging Robotics, an Israeli company, announced in October 2026 an inductive wireless charging platform for robotaxis and autonomous fleets. According to the release, the system is designed to deliver up to 10 kW and up to 95% efficiency under specified operating conditions.[1] Those are the company's claims.
Wireless charging removes plugs and cables and suits unattended operation. But at 10 kW the table above applies: a 70 kWh battery needs about seven hours before losses. That fits long-dwell parking. It does not fit a fleet that wants vehicles back on the road in 15 to 20 minutes, which takes power in the hundreds of kilowatts. For fast turnaround, high-power plug-in DC charging is what depots use today.
What does a fast-turnaround depot look like in practice?
Road to Autonomy's field report on a Waymo and Avis site in Dallas describes temporary skid-mounted DC fast chargers on generators at the working site, and a permanent hub under construction with about ten Alpitronic HYC-400 units, roughly 40 charging points, under canopies, with switchgear and transformer pads in place.[3] It is one reporter's observation of one site. It shows that heavy electrical work sits behind a fast-charging lot. The same issue shapes robotaxi sites generally; see our piece on robotaxi industrial real estate.
Questions to settle before you buy chargers
- What is the dwell time? Overnight fleets can use AC. Multi-shift fleets need DC.
- How many kWh per vehicle per day? Work from real route energy.
- What power can the site get, and by when? The utility timeline can be the longest task.
- Can charging be staggered? Load management lowers peak demand.
- What happens when a charger is down? Plan spare capacity and a service response.
Fleet Pit Stop is developing charging and depot servicing support for electric fleets, with Tesla Certified Installer capability on the electrical side. See our services or talk to us if you are sizing power for a depot.
Sources
[1] Clearmind Medicine / Charging Robotics release via GlobeNewswire, Oct 12, 2026 (company claims): Charging Robotics launches next-generation automated EV-charging technology
[2] U.S. Department of Energy, Alternative Fuels Data Center: Electric vehicle charging stations
[3] Road to Autonomy, Oct 12, 2026: Waymo Dallas Avis depot field report
Frequently asked questions
How long does it take to charge a fleet vehicle?
Divide the energy you need to add by the charger's power. A 70 kWh battery takes about 10 hours at 7 kW, about 3 hours 41 minutes at 19 kW, about 28 minutes at 150 kW and about 12 minutes at 350 kW, in best-case constant-power conditions. Real sessions take longer because charging tapers as the battery fills.
How many chargers does a fleet depot need?
It depends on dwell time and daily energy use per vehicle. If each vehicle can sit on its own charger overnight, you need roughly one per vehicle; faster chargers let several vehicles share one. Peak site power equals vehicles charging at once times charger power, so staggering can lower the utility load.
Is wireless charging fast enough for fleets?
At the 10 kW level one vendor describes, a 70 kWh battery needs about seven hours before losses. That suits long parking stays, not 15 to 20 minute turnarounds, which need power in the hundreds of kilowatts.
Why does DC fast charging take longer than the math says?
Charging power tapers as the battery fills, cold weather and battery health slow it, and the vehicle itself limits how much power it accepts. The simple formula gives a best case.
Independent commentary. Brand references describe public industry examples and do not imply affiliation. Operator and company claims are attributed, not independently audited.
Discuss your fleet