Renogy RBC2125DS-21W User manual

USER MANUAL
VERSION A0
January 5, 2024
Dual Input DC-DC On-Board with MPPT Battery Charger
Renogy
RBC2125DS-21W
12V/24V 50A IP67

Before Getting Started
The user manual provides important operation and maintenance instructions for Renogy 12V/24V 50A
IP67 Dual Input DC-DC On-Board with MPPT Battery Charger (hereinafter referred to as battery charger).
Read the user manual carefully before operation and save it for future reference. Failure to observe the
instructions or precautions in the user manual can result in electrical shock, serious injury, or death, or
can damage the battery charger, potentially rendering it inoperable.
zRenogy ensures the accuracy, sufficiency, and the applicability of information in the user manual
at the time of printing due to continual product improvements that may occur.
zRenogy assumes no responsibility or liability for personal and property losses, whether directly and
indirectly, caused by the user’s failure to install and use the product in compliance with the user
manual.
zRenogy is not responsible or liable for failures, damages, or injuries resulting from repair attempted
by unqualified personnel, improper installation, and unsuitable operation.
zThe illustrations in the user manual are for demonstration purposes only. Details may appear
slightly different depending on product revision and market region.
zRenogy reserves the right to change the information in the user manual without notice. For the
latest user manual, visit renogy.com.
Disclaimer
Renogy 12V/24V 50A IP67 Dual Input DC-DC On-Board with MPPT Battery Charger User Manual © 2024
Renogy. All rights reserved.
RENOGY and are registered trademarks of Renogy.
zAll information in the user manual is subject to copyright and other intellectual property rights of
Renogy and its licensors. The user manual may not be modified, reproduced, or copied, in whole or
in part, without the prior written permissions of Renogy and its licensors.
zThe registered trademarks in the user manual are the property of Renogy. The unauthorized use of
the trademarks is strictly prohibited.
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1. General Information ........................................................................................................................... 1
1.1. Symbols Used .............................................................................................................................................. 1
1.2. Introduction ................................................................................................................................................. 1
1.3. Key Features ................................................................................................................................................ 1
1.4. SKU................................................................................................................................................................. 1
2. Get to Know 12V/24V 50A DC-DC Battery Charger with MPPT .....................................................2
2.1. What’s In the Box?...................................................................................................................................... 2
2.2. Product Overview....................................................................................................................................... 2
2.3. System Setup ............................................................................................................................................. 3
3. Preparation .........................................................................................................................................4
3.1. Recommended Tools & Accessories ...................................................................................................... 4
3.2. Size Wires..................................................................................................................................................... 5
3.3. Plan a Mounting Site ................................................................................................................................. 5
3.4. Check the Battery Charger ...................................................................................................................... 6
3.5. Check the Auxiliary Battery ......................................................................................................................7
3.6. Check the Solar Panel(s)........................................................................................................................... 8
3.7. Check the Alternator on Your Automobile ...........................................................................................10
3.8. How to Install 15/32 in Lugs or 3/8 in Lugs?....................................................................................... 11
3.9. How to Install Cables on the Battery Charger?...................................................................................12
4. Installation ........................................................................................................................................ 15
4.1. Wear Insulating Gloves.............................................................................................................................15
4.2. Connect the Battery Charger to a Busbar ...........................................................................................15
4.3. Connect the Battery Charger to an Auxiliary Battery .......................................................................16
4.4. Connect the Battery Charger to a Solar Panel....................................................................................17
4.5. Connect the Battery Charger to a Starter Battery.............................................................................18
4.6. Install a Battery Temperature Sensor...................................................................................................19
4.7. CAN Communication Wiring (Optional).................................................................................................19
4.8. Wire Inspection......................................................................................................................................... 23
5. LED Indicators...................................................................................................................................24
6. Configuration....................................................................................................................................25
6.1. Set a Battery Type.................................................................................................................................... 25
6.2. User Mode.................................................................................................................................................. 25
6.3. Configure Charging Parameters........................................................................................................... 26
6.4. Activate Lithium Batteries..................................................................................................................... 27
7. Monitoring .........................................................................................................................................28
7.1. Short-Range Monitoring.........................................................................................................................28
7.2. Wireless Long-Range Monitoring ......................................................................................................... 29
7.3. Wired Long-Range Monitoring (Backbone Network)........................................................................30
7.4. Wired Long-Range Monitoring (Daisy Chain Network)......................................................................31
Table of Contents

8. Working & Charging Logic................................................................................................................32
8.1. Automatic Voltage Matching Function................................................................................................32
8.2. Charging Logic..........................................................................................................................................33
8.3. Battery Charging Stages........................................................................................................................ 35
9. Troubleshooting................................................................................................................................37
10. Dimensions & Specifications...........................................................................................................39
10.1. Dimensions................................................................................................................................................39
10.2. Technical Specifications......................................................................................................................... 39
11. Maintenance..................................................................................................................................... 40
11.1. Inspection.................................................................................................................................................40
11.2. Cleaning .....................................................................................................................................................40
11.3. Storage.......................................................................................................................................................40
12. Emergency Responses..................................................................................................................... 41
12.1. Fire ...............................................................................................................................................................41
12.2. Flooding ......................................................................................................................................................41
12.3. Smell ............................................................................................................................................................41
12.4. Noise............................................................................................................................................................41
Renogy Support ........................................................................................................................................42

— 1 —
1. General Information
1.1. Symbols Used
The following symbols are used throughout the user manual to highlight important information.
WARNING: Indicates a potentially hazardous condition that could result in personal injury or
death.
CAUTION: Indicates a critical procedure for safe and proper installation and operation.
NOTE: Indicates an important step or tip for optimal performance.
1.2. Introduction
Renogy 12V/24V 50A IP67 Dual Input DC-DC On-Board with MPPT Battery Charger allows you to
charge your house (auxiliary) battery from solar panels or the starter battery in your RV. It is a charging
device that not only converts direct current to the appropriate voltage for charging a battery but also
incorporates MPPT (Maximum Power Point Tracking) technology to optimize power conversion from
solar panels.
The battery charger is versatile and can be connected to either 12V or 24V auxiliary batteries. The built-
in buck converter module is designed to adapt to different voltage requirements, enabling 12V solar
panels to charge 24V batteries at their native voltage and 24V solar panels to charge 12V batteries at
their native voltage.
Thanks to the exclusive intelligent charging logic, the battery charger prioritizes solar energy and
automatically adjusts working modes based on sunlight intensity, efficiently charging your house
battery while easing the load on generators. The battery charger seamlessly switches to solar
charging in ample sunlight and smoothly transitions to generator charging during low light, ensuring
uninterrupted device power.
Equipped with intelligent boost and buck logic, it seamlessly accommodates 12V/24V voltage systems,
elevating DIY possibilities to the uttermost. Maximizing energy utilization, it boasts a robust 50A current
and an impressive 720W output power, making a slim, waterproof dual charging solution perfect for
confined spaces. You can embrace an eco-conscious charging experience without compromising
efficiency or space, redefining sustainable energy utilization with the battery charger.
1.3. Key Features
zIntelligent Boost and Buck Logic
Effortlessly converts between 12V and 24V systems with over 90% efficiency for boosting and 94%
for voltage reduction, offering a dual charging solution adaptable to various DIY configurations.
zPrioritize Solar Green Energy
Features auto-switching charging mode while prioritizing green power, achieving 97% charging
efficiency, and delivering 720W high charging power for a greener approach.
zIP67 Waterproof
Ensures robust safety standards with multiple certifications like CE, FCC,and RoHS, guaranteeing a
secure off-grid power experience alongside strong IP67 waterproof performance.
zExtremely Compact and Lightweight
Compact and light enough to be mounted in engine compartment and side storeroom, allowing for a
more spacious and comfortable living space.
zSmart Living Unleashed
Compatible with both built-in Bluetooth and wired CAN communication to get real-time data, striving
for the most reliable experience for off-grid users.
1.4. SKU
Renogy 12V/24V 50A IP67 Dual Input DC-DC On-Board
with MPPT Battery Charger RBC2125DS-21W

— 2 —
2. Get to Know 12V/24V 50A DC-DC Battery Charger with MPPT
2.1. What’s In the Box?
VERSION A0
January 5, 2024
Dual Input DC-DC On-Board with MPPT Battery Charger
Renogy
12V/24V 50A IP67
RBC2125DS-21W
QUICK GUIDE
Renogy 12V/24V 50A IP67
Dual Input DC-DC On-Board
with MPPT Battery Charger × 1
Quick Guide × 1
15/32 in Lugs
(M12 Ring Terminals) × 4
Battery Temperature
Sensor (3 m) × 1
Mounting Screws x 4
ST4*20 mm
Make sure that all accessories are complete and free of any signs of damage.
The accessories and product manual listed are crucial for the installation, excluding warranty
information and any additional items. Please note that the package contents may vary depending
on the specific product model.
The 15/32-inch lugs (M12 ring terminals) are used to connect starter battery on your vehicle to
your auxiliary battery.
2.2. Product Overview
█Right-side View
Battery Type
Setting Button
Battery Type Indicator
Auxiliary Battery Indicator
Alternator Charging Indicator
Solar Charging Indicator
Bluetooth Antenna

— 3 —
█Left-side View
Mounting Holes
CAN Communication Ports
Battery Temperature
Sensor Cable
(with connectors)
Positive Starter
Battery Cable (red)
Negative Common
Cable (black)
Positive Solar
Cable (yellow)
Positive Auxiliary
Battery Cable (brown)
2.3. System Setup
RV-C or Renogy devices supporting CAN communication
Solar Panel (s)
Auxiliary Battery
(12V / 24V)
Starter Battery
DC-DC Battery Charger
+
-
+
-
+
-
Communication
Temperature
Negative
Positive
The wiring diagram only shows the key components in a typical DC-coupled off-grid energy
storage system for the illustrative purpose. The wiring might be different depending on the
system configuration. Additional safety devices, including disconnect switches, emergency
stops, and rapid shutdown devices, might be required. Wire the system in accordance with the
regulations at the installation site.
The battery charger can be connected separately to the solar panel for charging the auxiliary
battery or to the vehicle’s starting battery for charging the auxiliary battery.

— 4 —
3. Preparation
3.1. Recommended Tools & Accessories
Measuring TapeInsulation Tape
3
4
5
6
Insulating Gloves
Phillips
Screwdriver (#1) Wire stripper
Manual Hydraulic Pliers
Heat Gun
Heat Shrink Tubing
Butt-Splices
3/8 in Lugs (M10 Ring Terminals) Busbar (60A to 100A)
Bare Wires
Prior to installing and configuring the battery charger, prepare the recommended tools,
components, and accessories.
Choose proper mounting screws specific to your installation site. This manual takes self-tapping
screws for wooden walls as an example.
The 3/8-inch lugs (M10 ring terminals) are used to connect the busbar and ANL fuse.
For how to size bare wires, refer to “3.2. Size Wires” in this manual.
In this manual, the red cable represents the positive cable, and the gray cable represents the
negative cable.
Do not use the bare wire if there is any visible damage.

— 5 —
3.2. Size Wires
Select proper bare wires based on the cable length in your power system. Refer to the table below for
recommended gauge sizes.
Cable Cable Length Cable Gauge Size
Output
(to Auxiliary Battery)
0 ft to 10 ft (0 m to 3 m) 10 AWG (5.25 mm²)
11 ft to 20 ft (3 m to 6 m) 8 AWG (8.36 mm²)
21 ft to 30 ft (6 m to 9 m) 6 AWG (13.3 mm²)
Input
(from Starter Battery)
0 ft to 10 ft (0 m to 3 m) 10 AWG (5.25 mm²)
11 ft to 20 ft (3 m to 6 m) 8 AWG (8.36 mm²)
21 ft to 30 ft (6 m to 9 m) 6 AWG (13.3 mm²)
Input
(from Solar Panel)
0 ft to 10 ft (0 m to 3 m) 12 AWG (3.31 mm²)
11 ft to 20 ft (3 m to 6 m) 10 AWG (5.25 mm²)
21 ft to 30 ft (6 m to 9 m) 10 AWG (5.25 mm²)
The cable specifications listed above account for critical, less than 3% voltage drop and may not
account for all configurations.
The specification of fuse cable is consistent with the input or output terminal of the battery
charger.
3.3. Plan a Mounting Site
The battery charger requires adequate clearance for installation, wiring and ventilation. The minimum
clearance is provided below. Ventilation is highly recommended if it is mounted in an enclosure. Select
a proper mounting site to ensure the battery charger can be safely connected to the battery, solar
panel(s), and the other necessary devices with the relevant cables.
You can mounting the battery charger vertically on a wall or horizontally on the floor.
5.91 in
(150 mm)
5.91 in
(150 mm)
5.91 in
(150 mm)
FRAGILE VENTILATION
0% to 95%
-31°F to 176°F
-35°C to 80°C
SolarVehicle Stage Battery
5.91 in
(150 mm)
Solar Vehicle Stage Battery
Risk of explosion! Never install the battery charger in a sealed enclosure with flooded batteries!
Do not install the battery charger in a confined area where battery gases can accumulate.
The battery charger should be installed on a flat surface protected from direct sunlight.
Keep the battery charger out of the reach of children and animals.

— 6 —
Do not expose the battery charger to flammable or harsh chemicals or vapors.
Make sure that the battery charger is installed in a place at ambient temperature from -31°F to
176°F (-35°C to 80°C).
Make sure that the battery charger is installed in an environment with relative humidity between
0% and 95% and no condensation.
If the battery charger is installed improperly on a boat, it may cause damage to components of
the boat. Have the battery charger by a qualified electrician.
The battery charger should be as close to the battery as possible to avoid voltage drop due to
long cables.
It is recommended that all cables (except communication cables) should not exceed 10 meters
(32.8 feet) because excessively long cables result in a voltage drop. The communication cables
should be shorter than 6 m (19.6 feet).
The cable specifications listed in the user manual account for critical, less than 3% voltage drop
and may not account for all configurations.
Keep the battery charger away from EMI receptors such as TVs, radios, and other audio/visual
electronics to prevent damage or interference to the equipment.
3.4.Check the Battery Charger
Inspect the battery charger for any visible damage including cracks,
dents, deformation, and other visible abnormalities. All connector
contacts shall be clean, free of dirt and corrosion, and dry.
Do not use the battery charger if there is any visible damage.
Do not puncture, drop, crush, penetrate, shake, strike, or step on the battery charger.
There are no serviceable parts in the battery charger. Do not open, dismantle, repair, tamper with,
or modify the battery charger.
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damage to the battery charger and other connected devices, thus voiding the warranty.
Do not touch the connector contacts while the battery charger is in operation.
Wear proper protective equipment and use insulated tools during installation and operation. Do
not wear jewelry or other metal objects when working on or around the battery charger.
Do not dispose of the battery charger as household waste. Comply with local, state, and federal
laws and regulations and use recycling channels as required.