How to Set Up a DC-DC Charger

Adding a dual battery system to your camper, caravan, or 4WD will undoubtedly take your off-grid adventures to the next level - and one of the key components to this system running efficiently is your DC-DC charger.

The components you need

Before beginning any installation, it’s important to make sure you have all the tools and components needed to complete the installation safely. Every DC system will be a little bit different, to suit the specific needs of your individual vehicle, however, there are some basic tools and components you’ll need for a simple DC-DC Charger setup.

Firstly, you’ll need your two power sources: your starter battery and your auxiliary battery, and you’ll need a DC-DC charger suitable for your batteries and loads.

In addition to these components, you’ll need some cables and cable accessories, depending on where your auxiliary battery and DC-DC charger will be in comparison to the starter battery. As a rough guide, you’ll need some heavy-duty cables to connect your starter battery & some lighter-duty cables for your ignition connection. Where you can, we recommend using pre-wired kits with built-in fuse holders for extra protection.

If you’re needing to cut and connect cables, you will also need some good quality cable cutters and crimpers, cable lugs, and some heat-shrink tubing to seal off the connections. It’s also important to protect your circuits with circuit breakers and fuses in fuse holders where they’re required.

If your installation requires stripping and connecting cables, we recommend that you ask a qualified electrician to perform these procedures.

Finally, you’ll need some basic bits and pieces to finish off and tidy up your installation. This may include any nuts, bolts & washers for mounting components in the system, and some cable ties and conduit to run your cables together neatly.

Before starting your installation, you must disconnect your battery from any live power source and ensure that the system is safe for you to begin.

Setting up the DC-DC Charger

There are several different ways to set up a DC-DC charger within a dual battery system, as each individual system will be tailored to suit the needs of whatever it is powering. This means the specific wiring for your DC-DC charger might vary slightly, but there are some basic rules to follow to get your system working properly.

Installing a Non-Isolated Charger:

A cable connecting the negative terminal (‘Battery -’) on the auxiliary battery to the ‘Ground’ terminal (GND) on the DC-DC charger, which is also bolted to the chassis of the vehicle
A cable connecting the positive terminal (‘Battery +’) on the auxiliary battery to the ‘Output Positive’ terminal (OUT +) on the DC-DC charger (this connection should be fused)
A cable connecting the ‘Input Positive terminal’ (IN+) on the DC-DC charger to the positive terminal (‘Battery +’) on the starter battery and the alternator (this connection should be fused)
A cable on the negative terminal (‘Battery -’) on the starter battery that is bolted to the chassis of the vehicle
A negative cable on the alternator that is bolted to the chassis of the vehicle

Below, we have provided a basic diagram of a solar and battery system to showcase how these components need to be connected to work together.

Installing an Isolated Charger:

A cable connecting the negative terminal (‘Battery -’) on the auxiliary battery to the ‘Output Negative’ terminal (OUT -) on the DC-DC charger
A cable connecting the positive terminal (‘Battery +’) on the auxiliary battery to the ‘Output Negative’ terminal (OUT -) on the DC-DC charger (this connection should be fused)
A cable connecting the ‘Input Positive’ terminal (‘IN +’) on the DC-DC charger to the positive terminal (‘Battery +’) on the starter battery and the alternator (this connection should be fused)
A cable connecting the ‘Input Negative’ terminal (‘IN -’) on the DC-DC charger to the negative terminal (‘Battery -’) on the starter battery and the alternator

Below, we have provided a basic diagram of a solar and battery system to showcase how these components need to be connected to work together.

Programming a Victron Orion DC-DC Charger

Once you have correctly connected the DC-DC charger to your system, you will need to program the charger so it can begin charging the batteries in your system. Most DC-DC chargers these days can be easily programmed via a compatible app on any smart device.

Below is a step-by-step guide to programming a Victron Orion DC-DC Charger. While other DC-DC charger brands will have their own specific steps to follow, the general concept outlined is the same.

1. Connect the DC-DC charger to your phone

Download the VictronConnect App
Find and select the DC-DC charger you have
Connect to the charger via Bluetooth
The DC-DC charger is now connected to your phone

2. Open the settings menu

3. Ensure the function is set to ‘Charger’

Sometimes the Victron DC-DC chargers come set to ‘Power Supply’, but it needs to be set to ‘Charger’ in order to work properly.

4. Ensure that the ‘Charger Enabled’ toggle is on

You know the toggle is ‘on' if the toggle is to the right and is shaded blue. If it’s to the left and shaded grey, it is off, and you need to tap it to turn it on.

With the Orion XS, you can change your current limits. This is not available in the other Victron DC-DC charger models, and therefore, the ‘current limits’ section will not be shown on this screen. If you have an Orion XS and you have a specific need to reduce your current limits, you can do so in here, but for the basic programming, this can be left at its default settings

5. Click on ‘Battery Settings’ to open this setting

This is where you will need to set the parameters for the battery you want to charge.

If you have a more complex system, you can create your own profile within this section. You can just select ‘user defined’ instead of ‘select preset’ and you can input your specific parameters in here.

6. Click on ‘Factory Default’ to open the dropdown.

Choose ‘Select Preset’ to open the preset menu.
In this menu, select the type of battery you want to charge, i.e. AGM, lithium, etc.
Click OK to close the menu.
The app will then automatically fill in the parameters based on the type of battery you have selected.

7. Click the back arrow to return to the Settings menu

8. Click on ‘Engine Shutdown Detection’ to open this setting

This is where you will be telling the DC-DC charger when to turn on, when not to turn on and when to shut down based on the battery’s state of charge.

9. Ensure that the ‘Engine Shutdown Detection Enabled’ toggle is on

You know the toggle is ‘on' if the toggle is to the right and is shaded blue. If it’s to the left and shaded grey, it is off, and you need to tap it to turn it on.

10. Ensure that the alternator type is set to ‘Smart Alternator’

If it’s not, click on the dropdown menu and select ‘Smart Alternator’.

11. Click on ‘Start Voltage’ to open this setting

Change the Start Voltage to 13.2. This is essentially saying that once the start battery reaches 13.2V, the DC-DC charger can kick in and begin to charge the auxiliary battery. 13.2V is what we recommend for most vehicles.

12. Click on ‘Delayed Start Voltage’ to open this setting

This should be set to just below the start voltage. This allows the start battery to get charged once the alternator reaches the voltage for the time determined in the Delayed Start Voltage Delay setting. We recommend setting this to 13V, given that the Start Voltage is set to 13.2V.

13. Ensure that the ‘Delayed Start Voltage Delay’ is set to 120s

120s should be the default value that appears, but if it’s not, click on it to open the setting and change it to 120s.

14. Click on ‘Shutdown Voltage’ to open this setting

This is where you are telling the unit to turn off. If the input voltage drops below the set voltage for more than 60s, the charger will consider the engine to be turned off and will shut down and stop charging. We recommend setting this to 12.7V.

To get the most out of your charger and your system, we recommend that you measure your specific vehicle. You can do this by turning on the vehicle and using a voltage reader to measure the voltage you get from your alternator. However, these parameters are a general baseline that should be okay for most modern vehicles.

15. Click the back arrow to return to the Settings menu

16. Note the Input Voltage Lockout Setting

The last setting in this menu is the input voltage lockout setting. As a default, this should be set to 12.5V & 12.8V. This setting is a backup to the shutdown voltage settings we just programmed. The default settings are fine for a standard modern vehicle, and we recommend leaving them at the default setting.

17. The DC-DC charger is now connected & ready to begin charging

These are the basic settings that you will need to program to get your DC-DC charger set up and efficiently charging your dual battery system. These components are smart and have a variety of codes and algorithms that can be changed to best suit your needs. You can check out more of these specific settings in the VictonConnect Manual, however, these additional settings are not required for the ’basic’ DC-DC charger setup demonstrated in this blog.

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With an in-house team of 12V/24V experts, we can offer advice and support as you set up your off-grid, off-road, or DIY battery system. We are Queensland-based and house our stock, so check out our online store here or visit us at Lawnton or Capalaba for in-store help.

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