Planning a long journey
Turning range, charging curves and stop times into a real itinerary.
- Explain planning a long journey clearly and accurately
- Read the numbers that define the behaviour
- Apply the idea to a real charging session
Overview
Long-distance EV travel is an optimisation problem with a simple answer: more short stops, low arrival state of charge, and a warm pack.
In depth
Range Estimator
Realistic range from usable capacity, consumption and a reserve buffer.
range (km) = usable × (1 − reserve) ÷ consumption × 100Range is usable energy divided by consumption. Keeping a reserve means you never plan to arrive at 0%.
Example: 75 kWh, 10% reserve, 18 kWh/100 km → 67.5 ÷ 18 × 100 = 375 km.
- Motorway range is typically 25–35% below the WLTP figure.
- A 10% arrival reserve is the standard road-trip planning rule.
- Cold weather can cut range by 20–30% before preconditioning.
- 1Set the buffer
Plan to arrive at each stop with 10–15% remaining.
- 2Prefer the steep part
Charge 10–60% where power is highest.
- 3Precondition
Route through the navigation system so the pack warms on approach.
- 4Have a fallback
Note a second site within range of every planned stop.
Efficiency Calculator
Compare energy leaving the wall with energy doing useful work.
η (%) = useful output ÷ energy input × 100Every conversion stage loses a little energy as heat. Multiplying the stage efficiencies gives the end-to-end figure.
Example: 40 kWh drawn, 34.8 kWh reaching the wheels → 87% end-to-end efficiency.
- Motor + inverter typically exceed 90%; the charger and cell losses dominate.
- An efficiency below 80% on AC usually means a small charge on a high standby load.
- Regeneration recovers 60–70% of braking energy, not 100%.
Key takeaways
- Short, frequent stops beat long ones.
- Arrive low, leave at 60–80%.
- Modest speed reductions save large amounts of energy.
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