1. Introduction
This manual provides essential instructions for the safe installation, operation, and maintenance of your APC SMX120RMBP2U External Battery Pack. This unit is designed to extend the runtime of compatible APC Smart-UPS X RT 120V Uninterruptible Power Supply (UPS) systems. Please read this manual thoroughly before installation and operation to ensure proper use and to prevent equipment damage or injury.
2. Safety Information
Important Safety Instructions: Save these instructions. This manual contains important instructions that should be followed during installation and maintenance of the APC External Battery Pack and UPS.
- This battery pack contains sealed lead-acid batteries. Do not open or mutilate batteries. Released electrolyte is harmful to the skin and eyes. It may be toxic.
- A battery can present a risk of electrical shock and high short-circuit current. The following precautions should be observed when working on batteries:
- Remove watches, rings, or other metal objects.
- Use tools with insulated handles.
- Wear rubber gloves and boots.
- Do not lay tools or metal parts on top of batteries.
- Disconnect charging source prior to connecting or disconnecting battery terminals.
- Servicing of batteries should be performed or supervised by personnel knowledgeable about batteries and the required precautions.
- When replacing batteries, replace with the same type and number of batteries or battery packs.
- Do not dispose of batteries in a fire. The batteries may explode.
- Do not open or mutilate the battery. Released material is harmful to the skin and eyes and may be toxic.
3. Setup and Installation
3.1 Unpacking
Carefully unpack the battery pack and inspect it for shipping damage. If any damage is found, notify the carrier and your dealer. The packaging materials are recyclable; save them for reuse or dispose of them properly.
3.2 Physical Installation
The SMX120RMBP2U is designed for rack-mount installation. Ensure the rack is stable and capable of supporting the unit's weight (approximately 101.4 pounds). Install the battery pack in a location with adequate airflow to prevent overheating.

Figure 1: Front and rear view of the APC SMX120RMBP2U External Battery Pack, showing the power input/output and ventilation.

Figure 2: Angled view of the APC SMX120RMBP2U External Battery Pack, highlighting the rackmount ears for secure installation.
3.3 Connecting to a UPS
Connect the external battery pack to a compatible APC Smart-UPS X RT 120V UPS using the provided battery cable. Ensure the UPS is turned off and disconnected from utility power before making connections. Connect the battery pack cable to the external battery connector on the UPS. Secure all connections firmly.
After connecting the battery pack, connect the UPS to utility power and turn it on. The UPS will automatically detect the external battery pack and begin charging it.
4. Operation
Once connected and recognized by the UPS, the SMX120RMBP2U External Battery Pack operates automatically. It provides additional runtime during power outages, seamlessly integrating with the UPS's power management system.
- The UPS will display the combined battery capacity and estimated runtime.
- The battery pack charges whenever the UPS is connected to utility power.
- No user intervention is typically required during normal operation.
5. Maintenance
5.1 Battery Care
The SMX120RMBP2U uses sealed lead-acid batteries that are designed for a long service life (3 to 5 years). For optimal battery life, ensure the unit is operated within recommended environmental conditions (temperature and humidity).
- Avoid operating the unit in extreme temperatures.
- Keep ventilation openings clear of dust and debris.
- Regularly check the UPS display for any battery-related warnings or alarms.
5.2 Battery Replacement
The batteries within the SMX120RMBP2U are hot-swappable, meaning they can be replaced without powering down the connected UPS. However, it is recommended to consult the UPS user manual and APC support for specific battery replacement procedures. Always use genuine APC replacement battery cartridges (RBCs) to ensure compatibility and optimal performance.
Proper disposal of old batteries is crucial. Contact your local recycling center or APC for information on battery recycling programs.
6. Troubleshooting
If you experience issues with your SMX120RMBP2U External Battery Pack, refer to the troubleshooting section of your connected UPS user manual first. The UPS typically provides diagnostic information and error codes related to external battery packs.
- Battery Pack Not Detected: Ensure the battery cable is securely connected between the UPS and the battery pack. Verify the UPS is powered on.
- Reduced Runtime: This may indicate aging batteries. Check the battery health status on the UPS display. Consider battery replacement if necessary.
- Overheating: Ensure adequate ventilation around the battery pack. Clear any obstructions from the air vents.
For persistent issues, contact APC Technical Support.
7. Specifications
| Feature | Specification |
|---|---|
| Model Number | SMX120RMBP2U |
| Battery Type | Sealed Lead Acid (SLA) |
| Voltage | 120 Volts DC |
| Amperage | 12 Amps |
| Battery Life (Minimum) | 3 Years |
| Battery Life (Maximum) | 5 Years |
| Hot Swappable | Yes |
| Package Dimensions (H x W x D) | 23.62 x 9.45 x 9.45 inches |
| Item Weight | 101.4 pounds |
| Color | Black |
8. Warranty and Support
8.1 Warranty Information
APC by Schneider Electric provides a standard warranty for this product. For detailed warranty terms and conditions, please refer to the warranty card included with your product or visit the official APC website. Proof of purchase is required for warranty claims.
8.2 Technical Support
For technical assistance, product information, or troubleshooting, please contact APC Technical Support. Have your product model number (SMX120RMBP2U) and serial number ready when contacting support. You can find the serial number on a label on the unit, similar to the one shown below.

Figure 3: Example of a product label showing the model number and serial number. The serial number is typically a unique identifier for your specific unit.
Visit the official APC website for up-to-date contact information and online resources: www.apc.com/support





