Question 1

How many chargers does a 60-bus electric depot need?

Accepted Answer

Work backwards from the window, not the bus count. With about 200 kWh to replace per bus, 120 kW guns and a 21:30–05:15 window, 30 chargers move 60 buses in two rotations with roughly 45 minutes to spare. Then add three or four more for charger downtime and changeover overrun — the nominal answer has no tolerance in it.

Question 2

Do electric buses need mid-day charging, or is overnight enough?

Accepted Answer

On typical Indian intracity duty it depends on the block, not the fleet. At 1.38 kWh/km a 225 km day needs about 310 kWh, while 80% usable depth of discharge on a 250 kWh pack gives roughly 145 km. Blocks under about 145 km clear overnight; longer blocks need either a depot swing or a terminus top-up inserted into the schedule.

Question 3

What does a missed charge cost under a gross-cost contract?

Accepted Answer

Twice: the kilometres are not billed, and the shortfall counts against the service-level commitment. At around ₹70/km a bus that runs 60 km short loses about ₹4,200 that day, and SLA penalties are commonly capped at 10% of the monthly payment — 5% operational, 5% technical. On a 100-bus fleet that ceiling is roughly ₹23.6 lakh a month.

Question 4

Is pantograph opportunity charging worth it for an Indian city fleet?

Accepted Answer

Only where depot dwell is short — under about five hours — or where daily route distance exceeds roughly 1.4 times single-charge range with no mid-day depot swing available. A 10-minute top-up at 300 kW returns about 36 km, but it spends the layover that absorbs delay, so on a route with eight hours of overnight dwell the money does more good as extra depot guns.

Question 5

Why does the depot's power contract matter more than the bus specification?

Accepted Answer

Because chargers can out-draw the sanctioned load. Around 100 buses create 4–5 MW of demand and a 90-bus depot often runs on roughly 4 MW of sanctioned load, so 30 guns at 120 kW cannot all run flat out. Exceeding contract demand triggers penal charges, which makes staged ramping and per-gun power caps an operating requirement rather than an optimisation.

gross cost contract

Electric Bus Fleet Operations: Running A 100-Bus Timetable On Charge