• The metric
• Know your vehicles
• The 80% rule
• Power and windows
• Reliability
• Operations

The metric that matters is throughput

For a public site, the question is how many strangers show up. For a fleet, you already know. The questions are how many vehicles you can charge in a day, whether each one is ready on time, and what each charge costs. Utilization is an output, not the goal.

A fleet charger sitting idle for an hour because nobody moved the car is a staffing problem, not a demand problem. That distinction runs through everything below.

Know your vehicles

• Every model has its own charging curve. The peak number on the spec sheet lasts for a short stretch in the middle of the battery, and only if the pack is warm. The battery section explains why.
• The car's onboard charger caps Level 2. An 11 kW car on a 19.2 kW charger is an 11 kW car.
• 400-volt and 800-volt vehicles behave differently on the same charger, and some chargers can't give both full power.
• In a mixed fleet, plan around the slowest vehicle you charge often, not the fastest one in the brochure.
• Software updates change charging curves. What you measured last year may not be what you get today.

The 80% rule

Charging slows sharply as the battery fills. On a typical fast-charging curve, going from 80% to 100% can take as long as going from 20% to 80%. For one driver, that's an annoyance. For a fleet, it's a whole vehicle you didn't charge.

• Set a charge-to target by use. Most rental returns and dealer service turns only need 70% to 80%.
• Stop the session at the target automatically, through the charger, the software, or the vehicle's own charge limit, then move the car.
• Take cars to 100% only when the next trip genuinely needs it, and do it where time is cheap: overnight, on Level 2.

Power on site, and the charge window

• Power. Total site power decides how many chargers can run flat out at once. Shared power slows everyone down when the lot is busy, and managed charging keeps demand charges in check.
• The window. This is when cars are actually available to charge. A depot might have eight to ten hours overnight. A rental return lot sees a steady stream all day. A dealer service lot has whatever time falls between drop-off and pickup.
• Match the charger to the window. If a car sits for ten hours, Level 2 will finish it cheaply. If it has to go back out in an hour, only DC fast will get it there.

Reliability, success rate and compatibility

Fleets feel failures more than anyone. A failed public session loses one sale. A failed fleet session means a car isn't ready, a porter made a wasted trip, and the whole schedule slips.

• Track success rate by vehicle model, not just by charger. Compatibility problems are usually specific to one model on one software version.
• Test every model in your fleet on the exact hardware and software you plan to buy, before you buy it. Bring the cars to the vendor, or the vendor to the cars.
• Control firmware updates. An update that fixes one model can break another, and a fleet finds out at 6am.
• Budget for retries. A failed start costs a swap and someone's time, and the throughput tool counts it.
• Don't forget the network. A charger that can't reach its software can't start a session. See Connectivity.

Operations, where fleets are won

• Staff the moves. The people swapping cars set the ceiling as often as the chargers do. Count swaps per hour, not just chargers.
• Design the lot for flow. A queue lane, pull-through stalls, and cables that reach every model's charge port.
• Charge in priority order. The car leaving soonest charges first, and only to what its next trip needs.
• Use telematics. Know each car's charge level before it arrives, and stop sessions at target without anyone walking out to do it.
• Schedule around the rate. Shift what you can into cheap hours and cap site power at peak.
• Measure what matters. Vehicles ready on time, vehicles charged per port per day, success rate by model, and cost per charge.

Model your fleet