My RCR 72v Battery cuts out, losing range, won't charge

My RCR 72v Battery cuts out, losing range, won't charge

This guide explains what it means when your RCR 72v Battery will not accept a charge.

Common Symptoms

You may notice:

  • Bike has significantly reduced range
  • Bike cuts out prematurely 
  • Bike powers on only when plugged into the charger showing ~83.8V (full charge)
  • After unplugging, the bike stays on for ~15 seconds, then shuts off
  • You hear a double chirp when it powers down
  • Charger shows 83.8V, 0 amps
  • Charger fan does not engage
  • Battery does not appear to be charging

What This Means

If your bike only powers on while plugged in, has reduced range, or cuts out prematurely 

  • The battery cannot hold operational voltage on its own
  • The charger is temporarily supplying enough voltage to power the system
  • Once unplugged, the battery cannot sustain that voltage, causing shutdown
  • The battery is reaching it's end of life, unable to fully discharge the full capacity of the battery
  • Old battery age attributes to cell health, over time deteriorating 
  • The battery was left in storage for a long period of time without being cycled or left at 50%

Why This Happens

Lithium batteries require regular use and proper storage conditions to stay healthy.

A helpful way to think about it is like caring for a houseplant::

With regular attention and the right conditions, it stays healthy and ready to grow.

If it is left unattended for eight months without enough care, it may deteriorate to the point where it cannot fully recover.

Similarly, a battery that sits unused for extended periods—especially at improper charge levels—can degrade to the point where it no longer functions properly.

Low mileage does not necessarily mean a battery is still healthy. Battery condition is also affected by factors such as storage habits, time spent in storage, charge level during storage, and overall cycle frequency.

What You Can Try

Confirm which battery your RCR 72v is utilizing:

72v 23ah:
  • Unfortunately the 23ah battery does not have a Bluetooth BMS
  • This means cell health and data cannot be viewed or accessed.
  • The BMS in these batteries were manufactured with cost and convenience in mind, hence the lack of additional BMS features. 
For the 41ah
  • Attempt to connect to the Bluetooth BMS via the Xiaoxiang BMS app here:
  • Once connected, take a screenshot of the individual cell voltages 1-20
  • Create a support ticket and attach the screenshots for our team to take a look
    • If the battery is not discoverable by the BMS app, the battery is likely beyond operational voltage for the BMS to register voltage or connection. 
For the 45ah
  • Attempt to connect to the Bluetooth BMS via the Xiaoxiang BMS app here:
  • Once connected, take a screenshot of the individual cell voltages 1-20
  • Create a support ticket and attach the screenshots for our team to take a look
    • If the battery is not discoverable by the BMS app, the battery is likely beyond operational voltage for the BMS to register voltage or connection. 


At this point, the battery is likely unrecoverable.

We recommend Replacing the battery pack entirely

ONYX RCR 72v 45ah battery:
  1. Purchase Here
  2. Installation Guide
ONYX QS8 Discharge Cable (mandatory):
  1. Purchase Here
An alternative battery vendor we recommended: