Free
Depot charging calculator
Use this free depot charging calculator to estimate how much energy your fleet needs each night, how many AC and DC chargers to install and what size they should be, and how much grid capacity your depot needs, with and without load management.
Calculator
Size your depot charging
Your results
Estimates to guide planning, not a design.
–kWh from the grid per vehicle per day
–average kW per vehicle overnight
–AC chargers
–DC chargers
–kWh per night for the fleet
–kW capacity needed with load management
Assumptions and disclaimer. Results are planning estimates, not a design. Energy per vehicle includes a 20% allowance for winter weather and battery ageing and a 10% allowance for charging losses. Average power is energy divided by the charging window. Charger sizes are the smallest standard rating (7, 11 or 22 kW AC; 50, 100, 150 or 350 kW DC) that meets the need, never above what the vehicle can accept, because a larger charger adds cost without charging faster. DC charging slows as the battery fills, so real top-ups take longer than a flat-rate calculation suggests. Capacity with load management adds 25% headroom to the fleet's average load, a rule of thumb to check against your half-hourly meter data. DC chargers are shared on a rota, allowing 10 minutes per changeover. Check every vehicle model's specification and your site's electrical design with a qualified engineer.
How to use it
Getting reliable results
Get the inputs right
Use a busy day, not the average
Use real energy figures from telematics or trials
Allow for late returns and early starts
Take charge acceptance from each vehicle specification
Reading the results
One AC charger per vehicle, sized to what it needs
Load management sizes the grid to the average, not the peak
DC chargers only for vehicles that cannot wait
Amber messages show where to look harder
Questions
Frequently asked questions
How accurate is the depot charging calculator?
It gives planning estimates from the figures you enter. A full design should use half-hourly meter data, vehicle schedules and each model's charging limits.
Why size chargers to charge acceptance?
A vehicle charges no faster than its own limit, so a charger larger than it can accept adds cost without saving time.
Why does load management reduce the capacity needed?
It shares the available power between chargers, so the site never needs every charger running at full power at once.
What if my site does not have enough capacity?
Options include a flexible connection, battery storage and phasing the rollout, while the full connection is arranged.
What is charge acceptance?
It is the maximum power a vehicle can take: on AC, the rating of its on-board charger; on DC, its maximum DC charging power. Both are in the vehicle specification.
Does the calculator allow for charging losses and winter?
Yes. It adds 20% for winter weather and battery ageing and 10% for charging losses to the energy each vehicle needs.
Further reading
Depot charging insights
Insight
How many depot chargers do you need?
The worked example behind this calculator.
Learn more
Insight
Fleet depot charging: the complete guide
From vehicle data to chargers, power and contracts.
Learn more
Insight
Dynamic load management for depots
Charging more vehicles on the same supply.
Learn more
Tool
Which EV charging technology fits?
Eight questions to find your best-fit technology.
Learn more
Talk to us about your depot
Send us your results and we will tell you plainly what your depot needs: chargers, power, storage and the order to do it in.