Cold-chain electric vans: a marginal route, a shared DC pair and a 24-hour event
A grocery home-delivery operation runs 40 battery-electric 3.5 t vans with 60 kWh usable packs and an electric refrigeration unit drawing 2.6 kW on average and 4.5 kW during pull-down. Summer routes average 130 km at 0.28 kWh/km, and the fridge runs for about 70% of a seven-hour shift. Vans return with 9–14% state of charge. The depot has 20 single-phase 7 kW AC points and two shared 50 kW DC chargers on a 200 kVA supply, with about 60 kVA spare at the daytime peak. Drivers on the longest rural route - 155 km, six stops and 40 minutes of total door-open time - report range warnings at 40% state of charge. Winter testing on the same route shows a 22% range loss. The operations manager wants to add a seventh stop to the rural route and to lend three vans to a 24-hour promotional event.
1. Build the energy budget for the rural route and decide whether it is achievable as specified.
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Traction: 155 km × 0.28 kWh/km = 43.4 kWh. Refrigeration: 2.6 kW average over a seven-hour shift is about 18.2 kWh, plus roughly 1.3 kWh extra for pull-down during 40 minutes of door-open time at 4.5 kW. Cab heating or cooling and auxiliaries add around 4 kWh in summer.
Total is around 67 kWh against a 60 kWh usable pack. The route as specified is not achievable; the 9–14% returns apply to the shorter 130 km loops, not this one, and the warnings at 40% are the BMS correctly predicting the shortfall. Add a reserve of 10% for degradation and the requirement rises to about 74 kWh.
The honest options are a shorter loop, a mid-route opportunity charge, or a larger-battery vehicle for this route - not driver coaching.
2. Construct a nightly charging plan for the 40-van fleet against the depot's supply and charger assets.
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Fleet energy: 40 vans at roughly 52 kWh average is 2,080 kWh per night, about 2,250 kWh with 8% charging loss. Over an eight-hour window that is about 280 kW average, far above the 60 kVA spare at peak.
Two 50 kW DC chargers cannot carry the fleet; at best they deliver 800 kWh in eight hours, so reserve them for the two longest routes and for vans returning late. The 20 AC points at 7 kW total 140 kW if all run, which also exceeds the spare, so use OCPP charging profiles to stagger starts and cap total site import below the authorised figure, with a fallback contactor rather than relying on drivers.
Build the plan on measured 24-hour load data. If the cold store drops to 80 kVA overnight, available capacity roughly triples and the plan becomes workable; at daytime peak figures it does not. Present both cases to the operations manager with the connection-upgrade cost alongside.
3. Advise on the seventh stop and the 24-hour promotional event, with numbers.
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The seventh stop adds roughly 15 km: about 4.2 kWh traction plus 0.6 kWh extra fridge, so about 5 kWh, taking a marginal 67 kWh route to 72 kWh. Refuse it unless the route is re-planned with an opportunity charge at the store or a shorter loop; on the winter basis it is clearly impossible.
For the event, an always-on fridge in standby draws roughly 0.3–0.5 kW continuously, and the van would be out of the charging rotation for a full day, removing about 52 kWh of fleet capacity and one vehicle from the nightly sequence. Approve only with a dedicated static supply or a separate battery unit at the venue.
Set the precedent now: any route change is assessed on the winter figure of about 0.34 kWh/km with a 22% range loss and a 10% degradation reserve, not on the summer best case.