How to charge a robotaxi fleet
Depot charging, fast charging and timing: how to keep a robotaxi fleet charged without eating the margin, with cost per paid mile from the base case.
By Fleetsly · Updated
A robotaxi earns while it drives and costs money while it charges, so charging is a scheduling problem as much as an energy bill. This guide covers where to charge, when, and how to tell whether charging is eating your margin.
What charging costs one robotaxi
In the estimator’s base case, one car drives 100 paid miles a day plus 30% empty miles between rides, at 5.5 miles per kWh and $0.30 per kWh:
| Miles a year, incl. empty miles | 47,143 |
|---|---|
| Energy a year | 8,571 kWh |
| Charging cost a year | $2,571 |
| Per paid mile | $0.08 |
These are illustrative assumptions. Change the electricity price and efficiency in the earnings estimator to match your depot.
Depot charging vs fast charging
- Depot charging is usually the cheapest energy you can get, and it happens where the car is already parked for cleaning and inspection. The trade-off is time: a slower charger keeps the car off the road longer.
- Fast charging gets a car back on the road quickly, at a higher price per kWh. It is the right call when demand is high and every hour on the road earns more than the price difference.
Most fleets use both: depot charging overnight and in quiet hours, fast charging only when a car would otherwise miss a busy period.
When to charge
- Overnight and early morning, when demand is lowest and many utilities charge less.
- In the midday dip, for the cars with the lowest batteries.
- Staggered, so the whole fleet never sits on chargers at the same time.
Watch empty miles
Every mile between rides uses energy without earning a fare. In the base case, empty miles are 30% of all miles, so nearly a third of the charging bill pays for driving with no one inside. Comparing charging cost per paid mile per car shows which cars waste the most.
Track it per car
Record every session against the car that used it, and look at cost per paid mile each month. A car whose charging cost climbs while its paid miles fall is the first one to look at. For how charging fits into a full year’s P&L, read How much does a Tesla robotaxi earn?