Battery dies fast or range dropped

Range changes a lot with how and where you ride, so start by ruling out the easy causes. If range dropped suddenly rather than slowly, the battery or charger is more likely at fault.

Things that cut range without anything being broken

• Assist level. Bosch's own example shows roughly half the range in its strongest mode compared with its most economical one (Bosch owner guide).
• Load, terrain, wind and tire pressure. Bosch lists support level, riding style, air resistance, rider weight, tire pressure and terrain as range factors (Bosch battery FAQ). Check pressure against the range on the tire's sidewall (Aventon tire tips).
• Lots of braking and low effort. Bosch says frequent braking uses more power, and its drives are most efficient above 60 pedal revolutions a minute (Bosch owner guide).
• Cold. Shimano says charging at 5 C or below shortens range for that charge, and that it comes back once you charge at room temperature (Shimano winter battery tips). Bosch says to bring a battery below 0 C (32 F) up to room temperature before riding (Bosch battery FAQ).
• A brake rubbing. Lectric notes a wheel that stops within one or two turns after you stop pedaling may have brakes that need adjusting (Lectric).

Signs of a worn battery

• Range has slipped gradually over years of use. Bosch calls batteries wear parts, and says heavy use, heat and storing at very low or very high charge shorten their life (Bosch battery FAQ).
• The bike cuts out on hills or under load with charge still showing. Himiway says voltage drops during climbs and hard acceleration, and if the problem only shows under heavy load, the battery may be the cause (Himiway). See motor cuts out.
• A Shimano battery that self-discharged while sitting may not show full after charging. Shimano says to ride with assist for a while before charging again (Shimano STEPS FAQ).

What you can do

• Charge to full and ride a known route to compare, on flat ground if you're checking for cut-outs (Himiway).
• Use a lower assist level and lower gears for starts and climbs (Bosch owner guide).
• Store the battery indoors and partly charged if you won't ride for weeks. See battery care.
• Use only the maker's charger for your battery, not a universal one (CPSC charger warning).
• If the pack is worn out, get the maker's replacement first. If it isn't sold anymore, see battery rebuilders and replacement pack builders.

Get it checked if

• The bike cuts out under load with charge showing.
• Range dropped by a lot in a short time.

A shop can test the pack and tell you whether it's the battery, the charger or the bike. If it's worn out, replace it with a pack the maker approves (CPSC micromobility center). Charging trouble? See battery won't charge.

Sources

• eBike owner's guide (US), Bosch eBike Systems
• 12 questions about your eBike battery, Bosch eBike Systems
• Ebike tire pressure best practices, Aventon
• Looking after your e-bike battery in winter, Shimano
• New bike brakes rubbing or squealing, Lectric eBikes
• Why does my ebike motor keep cutting out, Himiway
• Shimano STEPS FAQ, Shimano
• Warning on universal chargers, CPSC
• E-bike and scooter safety tips, UL Standards and Engagement
• Micromobility information center, CPSC

Stuck after these checks? Find a shop near you.