Batteries
Used electric bike batteries are the cheapest route to more range or a straight replacement, since your e-bike is only as powerful as the pack it carries. At Cranxs you'll find new and second-hand batteries from brands including Bosch, Shimano and Specialized, listed directly by the sellers who own them.
Will it fit my bike?
Battery fit is not universal. Packs are built around a specific mount and a specific motor system, so a Bosch battery won't drop into a Shimano or Specialized frame, and even within one brand the generations differ. Check the part number on your existing pack against the listing before you buy, and ask the seller which bike and model year it came off. The wider electric components listings are the place to start if you're not sure what system you're running.
What should I check buying used?
Age and use matter more than looks. Ask how old the pack is, roughly how many charge cycles it has done and whether it has been stored fully charged or fully flat over winter, as both shorten a battery's life. Inspect the casing in the photos for cracks, dents or any swelling, check the contacts for corrosion, and walk away from anything that has been dropped or opened up.
How much range do you need?
Range depends on capacity, but also on your weight, the terrain and how much assistance you use. Long-range options make sense for touring and hilly commutes, while a smaller, lighter pack is often enough for short trips around town. Some riders buy a second battery rather than a bigger one, carrying it for the days that need it.
Do you need a charger as well?
Batteries and chargers are often sold separately, and a pack with no charger is worth less to you than the price suggests. Confirm what's included before you commit, and if you need one, look at e-bike chargers for the matching system. Quick-charging units exist for most of the major brands and are worth the extra if you turn the bike around between rides.
Replacing a battery or building an e-bike?
If you're buying a pack as part of a bigger project rather than a straight swap, conversion kits bundle the motor, battery and wiring so the parts are known to work together. Buying a battery on its own makes most sense when you already know the system and just want more range on the bike you have.