Knowledge base
Battery
Possible causes
- Aged cells, increased internal resistance
- Weak or discharged cell group
- Contact fault at battery connector/mount
- BMS protection or BMS fault
Safe test steps
- Resting voltage at the pack output vs. the nominal class (S × 3.6 V nominal, S × 4.20 V full for Li-ion).
- Load test with current: R = ΔU / I (E-Bike Doctor battery calculator).
- Condition of mount contacts, discoloration, play.
Workshop reference values
- Li-ion cell: 3.6–3.7 V nominal, 4.20 V full; manufacturer minimum typically 2.5–3.0 V (per datasheet).
- Pack full voltage (Li-ion): 7S 29.4 V · 10S 42.0 V · 13S 54.6 V · 14S 58.8 V.
Repair approach
- Full charge with the original charger, then re-measure.
- Pack repair/re-celling only by a qualified battery shop with identical matched cells; otherwise replace the pack.
Tools needed
- Digital multimeter (CAT III, fused inputs)
- Fused load tester or clamp meter
- Manufacturer dealer diagnostic tool/software (if available)
Safety
- Do not charge or open a swollen, hot, damaged, hissing or smelling pack – isolate it safely.
- Never connect an ammeter directly across the battery. Never bypass the BMS.
Related verified fault codes
| Code | Meaning | Component | Reliability |
|---|---|---|---|
| Bosch 530 | Battery fault | Battery | Per manufacturer documentation |
| Bosch 602 | Internal battery fault during charging | Battery | Per manufacturer documentation |
| Bosch 603 | Internal battery fault | Battery | Per manufacturer documentation |
| Bosch 606 | External battery fault | Battery | Per manufacturer documentation |
| Bosch 640 | Internal battery fault | Battery | Per manufacturer documentation |
| Bosch 655 | Multiple battery fault | Battery | Per manufacturer documentation |
| Shimano STEPS E021 | Connected battery conforms to the standard but is not supported | Battery | Per manufacturer documentation |
| Shimano STEPS E022 | Connected battery does not conform to system standards | Battery | Per manufacturer documentation |
| Bafang 43 | Total power from battery cells too high | Battery | Per manufacturer documentation |