Depot Charging vs Public Charging for Fleets: Which Lowers Your Cost per Mile?
Every fleet manager I talk to is running the same comparison study. When you put depot charging vs public charging for fleets side by side, the gap shows up in two places: your cost per mile and your on-time window. The public network looks easy on day one. The depot approach looks expensive on paper. But from our fleet's data, the real total cost flips once you count downtime, driver pay, and the questions your DOT inspector will ask. What it costs, what it pays back, what it triggers with DOT.
The Real Cost Split: Depot Charging vs Public Charging for Fleets
The quickest way to compare these options is your cost per mile, not the sticker price of a charger. On public fast charging, a commercial EV running 1.8 kWh per mile at 45 cents per kWh costs about 81 cents a mile just for energy. At 65 cents per kWh, that jumps past $1.17. Over 10,000 miles, that's an $8,100 to $11,700 energy bill for a single vehicle. Depot electricity from the utility, meanwhile, often lands between 10 and 16 cents per kWh depending on your rate class. Same truck, same route, and you're looking at 18 to 29 cents a mile. That gap alone is $5,400 to $9,000 a year per truck. This three-way split is why depot charging vs public charging for fleets is not a decision you can make from a spec sheet alone.
The public side also includes session fees, idle fees, and the time your driver waits while the battery climbs from 20 to 80 percent. A 150 kW station adds meaningful range in 45 minutes, but on route schedules, 45 minutes can kill a 6-hour window.
Why Public Charging Punishes the Schedule
The second number your CFO will ignore until it's too late is driver hours. Every minute a driver spends waiting at a charging station counts against their 14-hour on-duty window. A public charger that's down, a cable that won't lock, or a line of three trucks ahead means the truck sits, and you pay for it. In our pilot, we lost 55 minutes of productive time per public charging stop. At an average loaded cost of $45 an hour per driver plus the truck, that's over $41 per stop in unproductive labor. Depot charging is the opposite: the truck backs into its stall, plugs in, and the driver clocks out.
Depot charging also lets you use smart load management to finish charging by a fixed pull-out time. Chargers talk to your telematics, prioritize trucks with morning dispatch, and defer the rest. Public charging gives you none of that control.
The Payback Math for Depot Chargers
If you're doing the depot math, the hardware is real money. A dual-port 150 kW DC charger installed runs about $80,000 to $150,000 when you include electrical upgrades and the pad. But the payback comes from four streams: energy cost savings, elimination of idle time, reduced driver overtime, and the federal tax incentive for commercial EV charging infrastructure, which can cover a meaningful share of the installation cost if you qualify. On a 10-truck EV fleet running 12,000 miles a year, energy savings alone can be $54,000 to $90,000 annually. Add the labor recovery, and a $250,000 depot installation pays back in roughly 30 to 36 months. The exact number depends on your utility rates and duty cycle, but it holds up on paper in almost every region we've modeled.
Fleet Impact: With 20 or more EVs, the cost per stall drops because the transformer, not the charger, is the main cost driver.
DOT and Compliance: What Actually Changes
DOT doesn't have a checkbox for your charging brand, but your charging choice shows up in compliance in two ways. First, driver hours: with public charging, the waiting time is not off-duty unless the driver logs it properly, and many drivers won't want to log a 50-minute stop as off-duty when they're stuck on the road. That creates pressure to drive back to the yard with low state of charge, which is a risk. Second, if you install depot charging, you trigger local building, electrical, and fire codes that become part of your facility audit. That's not a bad thing; it's just a line item. The FMCSA doesn't certify chargers, but your safety audit will ask how you ensure vehicles are available and drivers aren't exceeding hours. Depot charging gives you a clean answer.
A Step-by-Step Path From Public Charging to Depot Charging
You don't have to flip an entire fleet overnight. Start with the 10 or 15 vehicles that return to the same yard every night. Install Level 2 charging first if your routes are under 100 miles; the cheap, overnight approach works there. Keep public DC charging only for the long-haul exceptions and breakdowns. Run a six-month pilot tracking cost per mile, driver hours, and missed departures. From our fleet's data, the depot group showed a 30 percent lower energy cost per mile and zero departure delays, while the public-charging group had more variability. Once the pilot confirms your numbers, expand in phases and apply for utility make-ready programs before you order transformers. That gives you cost certainty before you commit the capital.
The decision comes down to your route structure and your willingness to invest in infrastructure. If every truck sleeps in your yard, depot charging vs public charging for fleets becomes a simple math problem. Start with the pilot. Run the numbers with your utility and your finance team. And if you want my read on a specific charger vendor, ask me in the comments — I'll share what our data says.