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How to identify and measure your e-bike battery
Identifying a battery is less about the pack itself and more about the system it belongs to, because the motor, mount and connector together decide what will fit.
Start with the label
Almost every pack carries a label with its nominal voltage, amp-hours and often watt-hours, plus a model or part number. Record all of these. The voltage tells you the electrical family, and the part number is the fastest route to an exact replacement.
If the label is worn, the three electrical numbers are self-checking: voltage times amp-hours should equal the watt-hours, so you can recover a missing value from the other two.
Identify the motor system
Branded batteries are tied to a motor system rather than sold as generic parts, so identifying the motor is the key step. Look for a Bosch, Shimano, Yamaha, Brose or Bafang mark on the motor housing near the cranks, and note the exact system name such as Bosch Smart System or Shimano STEPS EP8.
The system name narrows the battery choice to the packs built for that mount and communication. This is why the finder starts from the system, not from the battery.
Record the mount and connector
Note how the pack attaches: an in-tube rail, an external cradle, or a rack base. Photograph the mount and the lock, and note whether the pack slides down the down tube or clips to a rack. For conversion kits, identify the connector type between pack and controller, such as an XT60 or a barrel plug, and confirm its polarity.
These physical details decide fit as firmly as the voltage does. Two 36V packs are only interchangeable if their mounts and contacts also match.
Measure only when there is no part number
For unbranded or older conversion packs with no useful markings, measure the case dimensions and the mounting hole or rail spacing with a caliper or tape, and note the connector. Combined with the measured pack voltage, these dimensions let you find a physically compatible replacement even without a model number.
Identify your system, then find the battery
Open the Fit My E-bike system finderPick your motor system to see the packs that fit it.Find e-bike battery by model on eBayaffiliateRelated
Sources: Bosch eBike Systems battery identification guide ยท Shimano STEPS dealer documentation