If your BMS app shows the battery is charged between 83V and 84V but displays 36Ah out of 41Ah instead of the expected 40Ah, this discrepancy suggests the need for recalibration.

Onyx 41AH - BMS Apps Download

Battery Settings Instructions

Ensure your BMS (Battery Management System) settings are accurate. Stand near your battery for better connectivity.

Connect to the Overkill Solar BMS App or Xiaoxiang BMS App

  • Connect to your Onyx 41Ah battery (either the “EK” or “HD” model).
  • Tap “Settings” (bottom left of the screen) and select “BMS Read.”
  • Verify that your settings match the recommended values below. If not, correct them, then tap “BMS Write” to save changes. A popup will confirm the update.

Note: Some Onyx 41Ah BMS readouts display percentages between 80% and 20%, while others display from 100% to 10%. Both configurations are listed below.

Readouts From 80% To 20%

  • 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

Readouts From 100% To 10%

  • 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

What Does Nominal Voltage Mean

Nominal voltage can be understood at 50% charge which for 18650 and 21700 is generally regarded as 3.6v or 3.7v per cell.

Calibration Instructions

  • Ensure the battery is not connected to the bike or charger.
  • The battery voltage should be anywhere between 61V and 84V.
  • Follow the steps below, and once completed, fully charge the battery. You may need to repeat the process once the battery is fully charged (between 83V and 84V).

Calibration Steps

  • Open the Xiaoxiang BMS App and connect to your battery.
  • Tap the Config button (bottom left).
  • Tap the Current Cal icon (bottom center).
  • Enable the “BMS Calibration Function.”
  • Tap Idle Calibration.

The recalibration process may take between 5 minutes to an hour to adjust the voltage, percentage, and amp-hour readings.