Depot charging for electric vans: calculate energy needs from routes and dwell times

The charging needs of a van depot are determined by the routes actually driven and the energy that must be replenished before the next departure. Battery size alone is not a suitable measure. For each vehicle, record its duty, return time, next departure window and realistic consumption. This allows you to check whether the available charging times are sufficient and what supply the depot must provide.

Start with a representative sample of routes

Do not simply take the average daily mileage from the fleet report. A regional delivery route, a motorway journey and a service run with many stops can face different conditions despite covering the same distance. Group duties according to a clear pattern and add demanding days that recur regularly.

Several weeks of actual operating data are helpful for an initial assessment, where available. Note any seasonal gaps in the sample. A period measured in summer cannot reliably represent winter. Initially use explicitly labelled scenarios for missing conditions and replace assumptions with measurements later.

The NOW quick guide to truck charging infrastructure at depots presents vehicle requirements, dwell times and the connection as interconnected planning factors. The calculation method below applies this logic to vans; it does not replace a design tailored to the vehicles and site.

What data you need for each route

A nominal return at 6 pm does not mean charging starts at 6 pm. Unloading, cleaning, workshop visits and repositioning may intervene. Similarly, the usable window may end before the scheduled departure because the vehicle needs another parking space for loading.

Record these deductions separately. This lets you identify later whether an energy shortfall comes from technology or from a process that can be changed.

Calculate battery requirements and electricity drawn separately

A hypothetical van travels 160 kilometres a day. For this example, battery-side consumption is assumed to be 25 kWh per 100 kilometres, including the auxiliary loads considered here. The daily requirement is therefore 40 kWh at the battery. This is not a consumption figure for any specific vehicle.

For charging planning, a further assumption is that 90 percent of the energy drawn at the charge point reaches this energy balance. The required draw is then 40 / 0.90 = approximately 44.4 kWh. The assumed proportion serves only for this calculation and is not a universal charging-loss figure. If suitable measured electricity-draw data is already available, losses must not be added again.

Different measurement boundaries are a common source of errors. The article on charging losses and charging invoices explains why a vehicle display and a charging meter do not necessarily show the same amount of energy.

Plan reserve as stored energy, not additional daily consumption

For its next route, the vehicle needs sufficient energy plus an agreed reserve. The amount to recharge is therefore the difference between the target energy before departure and the energy remaining on return. A reserve that is already present is not fully recharged again every evening.

Suppose the vehicle needs 50 kWh of usable energy before its next route and returns with 10 kWh. It is then short of 40 kWh at the battery. If it returns from a shorter route with 20 kWh, it needs only 30 kWh. This exact difference represents the actual charging requirement.

Set reserves according to the task. Unplanned additional trips or uncertain alternative stations may justify different buffers from a short, fixed route. Avoid a uniform percentage without reference to the required distance and the specific vehicle.

Check each time window before total power

In the first example, approximately 44.4 kWh must be drawn over eight hours. This gives an average required power of around 5.6 kW. It does not mean that any charge point with that rated power will suffice: vehicle limits, interruptions, power management and actual charging behaviour must be compatible.

Eight such vans would require around 355.6 kWh in total. Over a fully shared eight-hour window, this works out at approximately 44.4 kW. If some vehicles return later, the daily energy requirement stays the same, but the power needed in the final hours may increase.

Create a schedule for each vehicle and add the requirements within shared windows. A daily average can hide a bottleneck just before the early shift. The supply is sufficient only when individual vehicles reach their targets by their respective departures.

Add the rest of the site's load

The charging infrastructure may share its connection with a workshop, refrigeration, heating or warehouse equipment. Compare charging demand and the existing load profile at the same times. Spare daytime capacity is of limited help for overnight charging if other major loads operate at night.

PV generation can change electricity purchases, but its timing does not automatically match a fleet that is out during the day. A storage system must be sized separately and assessed economically. It is not a freely available additional source of energy.

For the initial concept decision, show at least normal operation, a demanding day and planned expansion. Identify which assumptions come from measurements and which still need checking. Technical planning can then reduce uncertainty in a targeted way.

Identify operational alternatives before buying hardware

Some bottlenecks can be reduced through changes in process: connecting vehicles earlier, using a different space for loading or adjusting vehicle assignments. Check, however, whether staffing makes the change sustainable. A plan requiring spontaneous vehicle movements every night is reliable only if someone is responsible for them.

Other cases genuinely need more power or supplementary charging. A vehicle with a very short turnaround cannot receive the same charging provision as a van with a long overnight break. Assess public charging using reachable, suitable stations, rather than treating it as an unlimited reserve in a spreadsheet.

Turn the calculation into a depot assessment

The result should be a vehicle list with energy requirements, usable windows, target states of charge and unresolved assumptions. Add a site load profile and existing connection data. These documents are more informative than a blanket request for a particular number of rapid chargers.

StromNow Logistics describes depot planning based on routes, dwell times and available grid capacity. Bring precisely this data to an assessment of your van depot. Then agree a test with typical and demanding routes so that the design is assessed against vehicles being ready for duty on time.