Start with the exact cell model
Samsung, Panasonic and LG each offer different cells for different duties. Even cells of the same physical size can differ in capacity, discharge current, resistance and temperature limits. A high-capacity cell is not automatically suitable for sustained heavy loads. Ask for the complete model designation, its data sheet and batch records. Terms such as Grade A need measurable acceptance criteria, not just a label.
- Specify the cell model and approved alternatives in the order.
- Relate cell current limits to the controller and intended load.
Understand energy, current and range
A nominal 48 V, 20 Ah battery stores approximately 960 Wh: voltage multiplied by amp-hours. This compares nominal energy, not guaranteed range or climbing ability. Speed, total weight, gradient, tire pressure, temperature and assistance level change consumption. In an illustrative 13-series, 4-parallel pack delivering 20 A, each parallel cell would ideally supply 5 A. Real performance also depends on cell consistency and connection resistance; one weak group can trigger an early protection cutoff.
- Compare usable energy under stated test conditions.
- Check behavior on climbs and at a low state of charge.
Inspect the complete pack
Pack quality includes cell supports, welds, busbars, insulation, fuses, wiring, connectors, the enclosure and its attachment to the bicycle. A weak weld may heat up only under load; an unsecured cable may wear through after months of vibration. Sealing should be considered over the product's service life, including temperature changes and repeated battery removal. A good-looking sample does not demonstrate that later production uses the same materials and assembly controls.
- Ask how welds, insulation, sealing and final electrical checks are recorded.
- Keep an approved bill of materials and a controlled change record.
Check what the BMS actually protects
The battery management system monitors conditions such as cell-group voltage, pack current and temperature. Its thresholds must suit the cells and the application, and temperature sensors must monitor relevant hot spots. A list of protection features says little without settings and validation. Cell balancing can reduce differences between series groups, but it cannot repair damaged cells, poor welds or water ingress. Do not treat the BMS as a substitute for sound pack engineering.
- Request protection thresholds and sensor locations.
- Confirm whether fault information is available for service diagnosis.
Match the battery, charger and controller
A matching plug is not proof of compatibility. Charging voltage, current, polarity, charging profile, temperature limits and any communication protocol must agree with the specified battery. A conventional 13-series lithium-ion pack using 4.2 V cells typically reaches 54.6 V when fully charged, but this is not a universal charger specification for everything labeled 48 V. The controller's continuous and peak demand must also remain within the ratings of the cells, BMS, connections and wiring. Use the charger specified for the actual pack.
Read reports and lifetime claims in context
Transport testing, battery testing and whole-system evaluation serve different purposes. UN 38.3 concerns transport testing; UL 2271 addresses light electric vehicle batteries, while UL 2849 evaluates e-bike electrical-system combinations. None is a promise of a particular range or cycle life. Check the report's model, version, applicant and covered components. A cycle-life claim also needs charge and discharge conditions, temperature, depth of discharge and the remaining-capacity endpoint. Ask whether changes to cells, the BMS or the enclosure affect the documented configuration.
Apply the checklist to a WAYBYK order
Start a WAYBYK configuration request with the destination market, model, route, total load and daily distance. A WK-CT1 commuter and a WK-R1Pro used for deliveries may need different energy and current margins. The configurator lets buyers express cell-brand and range preferences; a selection is a request for review, not proof that every combination is available. Ask for the agreed cell model, battery and charger specifications, relevant documentation and service records in the written proposal. For after-sales diagnosis, retain the battery serial number, production date and configuration version.
- Cell identity → pack construction → protection → system compatibility → traceability.