ONYX 41Ah Battery BMS Fix

The original ONYX 41Ah battery is equipped with an 80A BMS, while newer versions come with a 100A model. Misconfigured settings-like incorrect “Charge” or “Discharge Overcurrent Protection” limits or an inaccurate “Total Cycle Capacity”-can lead to performance issues. If you’re noticing problems such as inaccurate charge readings or early cut-offs, it’s important to check and fine-tune your BMS settings.

Inconsistent charging habits can also raise the cell delta above 0.060, increasing the risk of cut-offs during acceleration or at lower voltages. Taking the time to properly configure your ONYX 41Ah battery helps ensure reliable performance and a longer lifespan.

Steps to Address Misconfigurations

  • Download the App: Install the Xiaoxiang BMS app.
  • Changes can be made whether the battery is installed in the bike, removed, or connected to a charger.
  • Ensure you are within 5 feet of the battery while using the app.
  • Connect to the Battery: Open the app, pair it with your Onyx 41Ah battery, and navigate to the Config tab.
  • Unlock Full Features: Purchase the Pro version of the app if necessary for advanced configurations.
  • Go to BMS Settings and tap BMS Read.
  • Total Battery Capacity: Ensure it’s set to 41000.
  • Total Cycle Capacity: Confirm it’s set to 32800. If incorrect, tap the field and update it to 32800.
  • Tap BMS Write in the top-right corner to save the updates.

Confirm and Apply Changes

  • Tap BMS Read again to ensure the new values are applied.
  • Scroll down to verify the following settings
  • 80A BMS
  • Charge Over Current: 90000
  • Discharge Over Current: 90000
  • 100A BMS:
  • Charge Over Current: 110000
  • Discharge Over Current: 110000
  • Adjust if Necessary:
  • If values differ, update them and save changes with BMS Write.

Balancer Configuration

  • Start Voltage: 3700
  • Delta to Balance: 15
  • Balance Only When Charging: OFF (Grey)

Monitoring Cell Balance

  • Open the Xiaoxiang BMS app and check the “Cells” reading, represented by a triangle below “Power” in the top-left corner.
  • A healthy cell balance for the Onyx RCR is 0.040 or lower.

Addressing High Balancer Readings

  • If the Value Exceeds 0.040:
  • Charge the battery fully.
  • Toggle “Balance Only When Charging” to OFF.
  • Allow 1–2 days for the cells to balance.
  • Target Reading:
  • Aim for a reading below 0.020.