RCR 72v 45ah Battery Upgrade

RCR 72v 45ah Battery Upgrade

This guide walks you through installing the ONYX 72v 45ah battery into your RCR, including connector compatibility and frame-specific fitment steps.

Before You Begin (Important)

  1. Purchase the RCR 72v 45ah Battery
    1. If we're out of stock, check out our recommended battery vendor: Amorge Batteries
  2. If your bike still uses the older red Anderson SB50-style connector, you’ll need to swap out your main battery cable to be QS8-compatible.
    1. 👉 Buy the ONYX QS8 Main Battery Cable
    2. ⚠️ Note: Anderson-style battery leads are not compatible with the new 45Ah ONYX batteries.
  3. If you have already installed the QS8 Main Battery Cable, continue to our Battery Fitment & Installation Guide

(OLD Red Anderson SB50-style connector pictured)


Step-by-Step Installation

1. Remove the Righthand Side Panel

To access one of the five panel screws, you'll need to remove the seat.
If you do not have a rear rack installed, you can instead loosen the four seat nuts and slide the seat backward and out of the way.

2. Unplug & Remove the Battery

Disconnect your battery and remove it from the tray.

3. Remove the Existing Battery Cable

Use a 14mm wrench to remove the two terminal nuts securing the existing Anderson battery lead.

Remove the old Anderson cable completely — it will no longer be used.

4. Install the QS8 Battery Cable

Route the new QS8 connector through the designated hole (see diagram/photo).

❌ Do not route it through the hole inside the battery tray — this will interfere with battery placement.

5. Connect to Terminal Posts

Attach the new positive (red) and negative (black) ring terminals to the matching posts.

These terminals should sit:
On top of the battery/controller lugs
Underneath the terminal post nuts

âś… Color Match Reminder:
Red → Yellow/Positive
Black → Black/Negative


6. Secure the Installation

Tighten the nuts using a 14mm wrench.
Reattach the righthand side panel.
Reinstall or slide the seat back into position and tighten seat nuts if loosened.

7. Install your 45ah! 

    • Related Articles

    • ONYX RCR 45Ah Battery Fitment & Installation Guide

      This guide walks you through installing the ONYX 45Ah 72V battery into your RCR, including connector compatibility and frame-specific fitment steps. Before You Begin (Important) This guide applies to riders installing the ONYX 45Ah 72V battery into ...

    • My RCR 72v Battery 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 powers on only when plugged into the charger Display shows ~83.8V (full charge) After unplugging, the bike stays on for ~15 ...

    • The ONYX 72v RCR Whisperer— John Angel

      If you’ve owned, researched, or seriously ridden an ONYX RCR—especially a 72V—there’s a very good chance you’ve come across John Angel. Known throughout the NYC e-bike scene as “the ONYX RCR whisperer” and often referred to as the godfather of NYC ...

    • RCR 72V Controller Guide

      Controller Overview The RCR 72V uses a Kelly KLS series controller. All wiring diagrams, configuration parameters, and error code definitions are handled through Kelly’s official documentation and software. This article provides an overview of the ...

    • RCR 72v 41Ah & 45Ah BMS Info / Connection Guide

      This guide walks you through identifying your battery, connecting to the correct BMS app, and checking battery health. Step 1: Identify Your Battery Before connecting, confirm which battery you have. 41Ah Battery Requires the Xiaoxiang BMS app ...