There is no standard ratio of DC chargers to vehicles. The count comes from your own duty data: how many vehicles need DC inside the same turnaround window, how long each session takes at the rate the vehicle accepts, and what happens when one unit is down. The five steps below run on your busiest recurring window.
Key Takeaways
- Count DC from the busiest window: simultaneous demand, session time at the vehicle’s accepted rate, sessions per unit.
- Decide the outage answer explicitly — spare unit, AC fallback, or accepted delay.
- DOE-cited U.S. figures put DC fast at about $38,000–$90,000 plus $20,000–$60,000 installed per unit — each unit in the count carries real money.
First, Only Count the Vehicles That Truly Need DC
Vehicles parked for eight to twelve hours take what they need at Level 2 rates — the U.S. DOT puts Level 2 at 7–19 kW — and our guide to sizing depot AC chargers for vans and light commercial vehicles works that side in full. DC enters the plan only for classes whose window is too short for AC to refill the next shift: two-shift vehicles, midday top-ups, standby units. A class that can be served overnight does not belong in the DC count — DC hardware is the expensive way to do an AC job.
The Count, Step by Step
| Step | What you count | Where the number comes from |
|---|---|---|
| 1. Vehicles needing DC per window | Classes that return and must leave again inside one turnaround window | Dispatch records for the busiest recurring window, not the average day |
| 2. Session time per vehicle | Energy the next shift needs, divided by the rate the vehicle accepts | The vehicle’s own handbook figure for DC acceptance; allow for taper as the battery fills |
| 3. Sessions one unit serves per window | Window length divided by session time | Your arithmetic from steps 1 and 2 |
| 4. Units for simultaneous demand | Vehicles per window divided by sessions per unit, rounded up | The ceiling the operation must cover at the same time |
| 5. The outage answer | What one unit down does to departures | Your decision: a spare unit, an AC fallback for some classes, or an accepted delay |
A single DC unit is a single point of failure: if the turnaround plan depends on it, its repair day becomes the fleet’s problem. Some depots answer with a second, smaller unit; some let part of the demand fall back to AC at lower readiness; some accept the risk because a delayed departure is cheap for them. There is no correct answer — only one your operation has actually chosen.
What Each Unit in the Count Costs
U.S. DOE-cited figures put DC fast charging at about $38,000–$90,000 in equipment plus $20,000–$60,000 in installation per unit (the DOT’s DC fast band is 50–350 kW). Every added unit repeats most of that stack — hardware, electrical work, its share of the supply. That is why the count matters: one unit too many is a five-figure rounding error; one too few shows up as vehicles leaving short.
Where EVDANCE’s Compact DC Fits — and Where It Does Not
The EV-RHDC30K-L is a compact DC charger at 22 kW, with OCPP 1.6J, IP54 and an LCD, in a single-connector floor-standing form. Say the boundary plainly: at 22 kW it sits below the DOT’s 50–350 kW DC fast band. A depot whose arithmetic needs band-class sessions — large energy inside very short windows, or the 150 kW-class ports U.S. corridor programmes specify — is shopping a different hardware class, and this unit is not it. For light-duty top-ups — an hour-class window restoring a working charge between duties — the pattern is one compact unit per simultaneous exception. One check before ordering: the listing does not name the DC connector standard, so confirm in writing that the fitted connector matches your vehicles. Depot plans can be brought to our commercial charging team or via contact us.
Frequently Asked Questions
Is there a standard ratio of DC chargers per vehicle?
No. A ratio ignores what decides the count: simultaneous demand, session time, and how much outage the operation tolerates. Identical fleets on different shift patterns need different counts.
Should a depot automatically buy one spare DC unit?
Only if a unit down stops departures that matter. If an AC fallback or a day’s delay covers the failure, the spare is optional; if a missed departure breaks a contract, the second unit is part of the real count, not an extra.
Can one DC charger serve two vehicles at the same time?
Not the EV-RHDC30K-L: it is single-connector, so it charges one vehicle at a time and its sessions are serial. Dual-connector hardware exists on the AC side — the EV-AC03201T serves two vehicles from one unit — but that is AC power, not DC turnaround power.
Related Reading
- Fleet Depot Charging: How to Size AC Chargers for Vans and Light Commercial Vehicles
- How Do DC Fast Chargers Work?
- Level 1 vs Level 2 vs DC Fast Charging: A Practical Comparison
