If your 41Ah battery behaves normally but its percentage or Ah reading looks wrong, the BMS readout may need calibration. This corrects reporting; it does not balance cell groups, repair weak cells, or recover lost capacity.
If the Problem Is Not the Readout
For genuine group imbalance, use 41Ah balancing . For extreme readings that change with movement, see the balance lead failure case .
ONYX 41Ah 72V Calibration
If voltage, percentage, and Ah readings do not align:
Example
- 83-84V reads ~36Ah instead of ~40Ah
Calibration corrects inaccurate readings. It does not repair damaged cells or restore lost battery health.
Calibration Steps
- disconnect battery from bike and charger
- ensure voltage between 61V and 84V
Steps:
- open Xiaoxiang app
- Config -> Current Cal
- enable calibration
- perform Idle Calibration
Duration:
- 5 minutes to 1 hour
ONYX 41Ah 72V Calibration Tables
80%-20% Readout
| Description | Value |
|---|---|
| Number of Cell | 20 |
| Total Battery Capacity | 41000 |
| Total Cycle Capacity | 32800 |
| Cell Full Voltage | 4150 |
| Cell Minimum Voltage | 3000 |
| Cell Self Discharge | 0.2 |
| Cell 80% Cap. Voltage | 4000 |
| Cell 60% Cap. Voltage | 3800 |
| Cell 40% Cap. Voltage | 3600 |
| Cell 20% Cap. Voltage | 3300 |
100%-10% Readout
| Description | Value |
|---|---|
| Number of Cell | 20 |
| Total Battery Capacity | 41000 |
| Total Cycle Capacity | 32800 |
| Cell Full Voltage | 4150 |
| Cell Minimum Voltage | 3000 |
| Cell Self Discharge | 0.2 |
| Cell 100% Cap. Voltage | 4150 |
| Cell 90% Cap. Voltage | 4100 |
| Cell 80% Cap. Voltage | 4000 |
| Cell 70% Cap. Voltage | 3700 |
| Cell 60% Cap. Voltage | 3800 |
| Cell 50% Cap. Voltage | 3700 |
| Cell 40% Cap. Voltage | 3600 |
| Cell 30% Cap. Voltage | 3500 |
| Cell 20% Cap. Voltage | 3300 |
| Cell 10% Cap. Voltage | 3200 |
41Ah BMS Calibration (Incorrect Percentage or Ah Readings)
This procedure corrects inaccurate State of Charge (SOC), percentage, and Ah readings reported by the BMS.
It does not fix imbalance, voltage sag, or weak performance. It only corrects how the battery data is reported.
When To Use This
- battery percentage drops too quickly
- battery shows empty while voltage is still high
- battery shows inconsistent or incorrect Ah usage
- range estimate does not match actual voltage behavior
If voltage behavior and performance are normal but the display is incorrect, this is a calibration issue.
Required Conditions
- battery must be disconnected from the bike
- battery must NOT be connected to a charger
- battery voltage must be between 61V and 84V
- use Xiaoxiang or compatible BMS app
Do not perform calibration while the battery is in use or charging.
Calibration Procedure
- open the BMS app
- connect to the battery
- go to Current Cal
- enable BMS Calibration Function
- run Idle Calibration
- wait for calibration to complete
- confirm values update correctly
Do not interact with the battery during calibration.
Readout Behavior Models
The 41Ah battery may report percentage using one of two internal models:
| Model | Behavior |
|---|---|
| 100% -> 10% | full-range reporting |
| 80% -> 20% | compressed reporting range |
This affects how percentage appears during use but does not change actual battery capacity.
Voltage is always the correct reference for true state of charge.
Important Notes
- this does not repair weak cells or imbalance
- this does not improve performance
- this does not affect voltage behavior
If the battery still:
- sags excessively
- cuts out early
- shows large cell delta
then the issue is not calibration.
Diagnostic Priority
Always verify:
- voltage behavior
- cell delta
- performance under load
before assuming the problem is calibration.
Calibration only fixes incorrect reporting, not actual battery condition.
If calibration is correct but cell delta remains elevated, proceed to imbalance correction.