How to build an AV fleet charging schedule that has every car ready by morning

How much energy does each robotaxi need back?

Start from the EPA rating, not the brochure. EPA lists a 2026 Hyundai Ioniq 5 under the name "Robo taxi" at 48 kWh per 100 miles and 168 miles of range.¹ The ordinary rear-drive 2026 Ioniq 5 is rated at 30 kWh per 100 miles and 318 miles.² Same body, 60% more energy per mile. EPA doesn't say why, but a robotaxi carries sensors and computers the regular car doesn't, so plan from the robotaxi figure if your cars have one.

Charging isn't free of losses. Fueleconomy.gov puts battery charging efficiency at 84% to 93%,³ and NREL's national charging study assumes 90% for AC charging.⁵ The meter at your service entrance sees the grid figure, so that is the number your schedule and your power bill run on.

Miles are the number you control least. Use a week of your own data, take each car's worst day rather than the average, and the schedule will hold on a busy Saturday.

How many hours does one charger give you in a night?

The Department of Energy's Alternative Fuels Data Center puts Level 2 equipment at 2.9 to 19.2 kW, on 40 to 80 amp circuits. DC fast chargers go up to 500 kW, but AFDC notes many EVs can't take more than 200 kW.⁴ The car sets the ceiling as often as the charger does.

DC charging also slows as the battery fills. NREL's 2030 network study describes the car's battery management system tapering its charge rate as state of charge rises, to protect the pack.⁵ Fueleconomy.gov puts even a fast charge to 80% at about 30 minutes.³ So a DC charger is quick from 20% to 80% and slow after. A car that has to go above 80% is usually better finished on Level 2, or left to finish while nobody else is waiting.

What sets the power a depot needs overnight?

This is the number to take to your utility and your electrician first. Shorten the window to 6 hours and the floor rises to 533 kW. Stretch it to 9 hours and it drops to 356 kW. Chargers only decide whether you can reach that floor, and how many times someone or something has to move a car.

Wiring is sized above the charger rating. EV charging counts as a continuous load, and the National Electrical Code requires the wiring and overcurrent protection for a charger to be 125% of its continuous output, as Pacific Northwest National Laboratory summarizes it.⁸ A 19.2 kW, 80 amp charger needs a 100 amp circuit. Twenty-four of them add up to a service that is easy to oversize if every charger is counted at full power.

In what order should the robotaxis charge?

• Sort by departure time, then by energy needed. The car that leaves first and needs the most starts first.
• Set a target, not 100%. Most cars only need what the next day's miles require plus a reserve; every kWh above that holds a charger for nothing.
• Put the low cars on DC and the nearly full cars on Level 2. DC is fast below 80% and slow above it.⁵
• Count the moves. Every swap is a person walking the yard or a car repositioning itself. A schedule that needs 40 moves at 2 a.m. fails on the night someone calls in sick.
• Leave one charger spare. A charger that faults at midnight should cost you one car's top-up, not the morning.

The waste in most yards isn't a slow charger. It is a full car still plugged in while an empty one waits. A full car holding a charger for two hours is two hours of 19.2 kW, about 38 kWh, that someone else didn't get.

How do you keep the whole yard under one power limit?

AFDC's fleet guidance says networking allows smart charging: scheduling charging at night, staggering vehicles and using lower off-peak rates, and it advises choosing chargers on OCPP 1.6 or higher so you can switch networks without new hardware.⁶ The Open Charge Alliance describes charging profiles as a schedule that sets how much power an EV may draw over time, including a default profile that allows charging only in off-peak hours.⁷

The payoff can be large. NREL found charge management could cut peak charging load at school bus depots by up to 77%.⁹ Buses aren't robotaxis, and nobody has published the same figure for a robotaxi yard, but the mechanism is the same: the cars are parked longer than they need to charge, so they don't all have to charge at once.

A lower cap means a smaller service and a lower demand charge. Demand charges bill your single busiest 15 or 30 minutes, so letting every charger start at the same moment at 11 p.m. can cost more than the energy itself.

We worked one night for a 40-car robotaxi yard

Our method: EPA's 48 kWh per 100 miles for the Ioniq 5 robotaxi,¹ NREL's 90% AC charging efficiency,⁵ and every car returning by 10 p.m. Twenty-four Level 2 chargers at 19.2 kW can supply 3,226 kWh in 7 hours, just over the 3,200 needed, but only if every charger is busy every minute. That leaves no room for a late car, a faulted charger or a move that takes ten minutes. In practice we would plan 28 to 30 chargers, or set the window an hour longer.

Four 150 kW DC chargers can also supply the energy, but they put the whole night's power through four plugs, which means a swap somewhere in the yard about every 12 minutes all night. The Level 2 yard needs about 16 swaps in the night; the DC yard needs about 36. For a yard where cars move themselves, DC is easier. For a yard where people move them, Level 2 is.

Your tariff may give you more than 7 hours. PG&E's business EV rate prices 9 p.m. to 9 a.m. as off-peak every day, a 12-hour window,¹² and NV Energy's EV recharge period runs from 12:01 a.m. to noon.¹³ Over 12 hours the same yard needs only 267 kW, and every charger has slack for a late car.

When an overnight schedule is the wrong plan

• Your cars run all night. If your service runs around the clock, there is no 7-hour window with every car parked. Plan staggered charging through the day and night instead, and size for the busiest hour.
• Your cheapest hours are in the middle of the day. PG&E's cheapest period is 9 a.m. to 2 p.m.¹² Check your time-of-use rate before you assume night is cheap.
• Your service can't reach the floor. If 3,200 kWh over 7 hours needs 457 kW and your utility can give you 300, no schedule fixes that. You need a longer window, fewer cars per site or a second site.
• You can't staff the moves. If nobody is on site at 2 a.m. and the cars can't reposition themselves, plan one car per charger and stop.

If the depot can't hold enough chargers, the cars can charge elsewhere. XoomPark arranges fleet charging at existing stations in the hours their stalls sit unused, never blocks a station's regular customers and never pushes the station past its monthly peak; when the station fills, the robotaxi leaves.

Questions depot managers ask