E-Bike Battery Range: What Affects It

E-bike makers quote a range, but the number you actually get can be half that or better than it. Here's what changes it, and how to estimate your own.

1. Range starts with battery energy

Battery energy is watt-hours (Wh), which is volts × amp-hours. A 36V 14Ah battery holds about 500Wh. A 48V 14Ah battery holds about 670Wh. More watt-hours means more range, all else being equal.

2. What uses that energy

Assist level: the biggest one. Riding in eco or low assist can use half the energy of turbo or high.
Throttle: riding on throttle alone, with little or no pedalling, uses far more than pedal assist.
Weight: rider, bags, kids' seat or a trailer all add to the work the motor does.
Hills and wind: climbing and headwinds use a lot. A flat, still day uses the least.
Stop-start riding: getting going again from a stop takes more than cruising.
Tyres: low pressure and knobbly tyres add drag.
Cold: lithium batteries give less in cold weather.
Battery age: an older battery holds less than it did new.

3. Rough energy use

As a rough guide with pedal assist on mixed riding:

Low assist, flat roads: about 7 to 10Wh per km.
Medium assist, some hills: about 10 to 15Wh per km.
High assist or hilly: about 15 to 20Wh per km.
Mostly throttle: 20Wh per km or more.

So a 500Wh battery might give about 50km on high assist and well over 60km on low. Work out your own with the E-Bike Range calculator.

4. Getting more range

Use a lower assist level on the flat and save the high levels for hills.
Change down gears before stopping and before climbs, so the motor isn't straining.
Keep the tyres pumped up to the pressure on the sidewall.
Pedal smoothly rather than hard bursts.
Store and charge the battery at room temperature where you can.

5. When range drops off

All lithium batteries lose capacity with age and charge cycles. If your range has dropped a lot in a short time, or the battery cuts out under load while it still shows charge, have it checked by the bike's dealer or maker. Don't open an e-bike battery yourself. They hold a lot of energy and need the right gear to handle safely.