Topic
Batteries, range and fixes
Battery size in Wh, real-world range, charging, storage and the faults that stop an e-bike working.
- Battery size
- V x Ah = Wh
- Typical use
- 10 to 25 Wh per mile
Battery capacity is energy: volts x amp-hours = watt-hours (Wh). A 504 Wh pack at 15 Wh per mile gives about 34 miles (54 km).
Hills, a heavy load, cold weather and high assist levels all raise the Wh per mile. Store a battery indoors, part charged, and use the charger made for it.
Common mistakes
- Charging a battery that has been dropped, swollen or soaked: replace it instead.
Guides on this topic
- What size e-bike battery do you need?Work out what size e-bike battery you need: volts times amp hours gives Wh, then match it to your commute distance, hills and how often you can charge.Guide
- How to store an e-bike battery over winterStore an e-bike battery over winter at the right charge level and temperature, in a safe spot indoors, with a simple top-up routine to protect it.How-to
- How to charge an e-bike batteryHow to charge an e-bike battery safely, how long a full charge takes, and the UK fire service advice on chargers, supervision and where to charge.How-to
- How long does an e-bike battery last?How long an e-bike battery lasts in charge cycles, years and miles per charge, plus the charging and storage habits that slow capacity loss.Guide
- E-bike range explained: what really affects itWhat sets e-bike range in real riding: battery Wh, rider weight, hills, assist level, tyre pressure and cold, and how to estimate miles from Wh per mile.Guide
- Why is my electric bike not working?Electric bike not working? Check the battery, key, connectors, brake cut-off sensors, display and motor cable in order before you book a shop visit.Fix
- E-bike motor cutting out: causes and fixesWhy an e-bike motor cuts out on hills or bumps: low-voltage cut-off, loose connectors, brake sensors, speed sensor magnets and overheating, with checks.Fix
- E-bike display not working: what to checkE-bike display blank, flickering or showing an error code? Trace the cause through the battery, plugs, settings and controller with these checks.Fix
- E-bike battery not charging: causes and fixesWhy an e-bike battery will not charge: charger lights, plug fuse, connectors, cold, deep discharge and BMS cut-outs, with safe checks and when to replace the pack.Fix
- How much does an e-bike battery cost to replace?What sets the price of a replacement e-bike battery, from Wh and cells to mount type, and how to work out the cost of each charge from your tariff.Guide
- 36 V vs 48 V e-bike batteriesWhy voltage alone does not decide e-bike power, range or UK legality, how 36 V and 48 V packs compare, and how to match a replacement battery to your controller.Comparison
Buying guides on this topic
- Best replacement e-bike batteriesReplacement e-bike batteries compared by voltage, Ah, mount style, connector, stated certification and size, so you can match your bike.Buying guide
- Best long range electric bikesRoad-legal 250 W e-bikes with the biggest batteries compared by Wh or V and Ah, the maker's claimed range, wheel size and weight.Buying guide