Charging a camper van’s leisure batteries while driving is a critical ability for those who require a reliable source of electricity during van life. This can be done by installing a DC-DC charger between your vehicle’s starting battery and your leisure batteries. And the installation process is not as difficult as you might think.
Though we always recommend installing solar panels for your camper, it’s important to have a second method to charge your leisure batteries. And for many, installing a DC-DC charger is a popular choice.
In this post, we will discuss what a DC-DC charger is and how to install one in a camper van. All the parts and components you need is included in this guide.
Let’s dive into it!
Charge your leisure batteries quickly with Victron's 30A DC-DC charger (up to 360W). Works great for both lithium and AGM batteries. But the highlight is the charger's Bluetooth connectivity, which pairs with Victron's UI-friendly smartphone app.
What Is A DC-DC Charger?
A DC-DC charger takes DC power from one battery and uses it to charge another battery. For camper vans and RVs, this device is most used to charge the leisure (house) batteries in the camper from the vehicle’s starting battery.
This charger is only activated when it senses that the engine is turned on. When the engine is off, the charger is also deactivated. This is to prevent the leisure battery from draining the starting battery. When the engine is on, there is no risk of draining the starter battery because the vehicle’s alternator ensures that the starter battery is continually being charged from the engine.
What Size DC-DC Charger Do You Need?
There are two specs to look at when determining which size DC-DC charger you need: DC voltage (V) rating and current (A) rating.
1. DC Voltage Rating
Before purchasing a DC-DC charger, you will need to know the following specs.
- Your starter battery voltage: In most cases, this battery will be rated for 12V.
- Your leisure battery voltage: A 12V leisure battery bank is most common, but some decide on a 24V system. (Read our 12V vs. 24V system post to learn more.)
Next, you need to find a DC-DC charger that accepts your starter battery voltage and outputs the correct voltage to your leisure battery.
- 12V starter battery and 12V leisure battery? Get a 12V/12V charger
- 12V starter battery and 24V leisure battery? Get a 12V/24V charger
- 24V starter battery and 12V leisure battery? Get a 24V/12V charger
- 24V start battery and 24V leisure battery? Get a 24V/24V charger
2. Current (Amps) Rating
The current (amp) rating of a DC-DC charger determines how fast the device will charge your leisure batteries. The greater the amp rating, the faster the charger, but also the more expensive the device will typically be.
DC-DC chargers come in several different current ratings. For example:
*All links above go to Amazon.com
Our Recommendation: If your daily energy usage is high (i.e. charging laptops, induction stove, heater), go with a charger that has a higher current (A) rating. But if you only need to charge cell phones and power some LED lights, a smaller charger is sufficient. We use the Victron 18A charger, but would upgrade to the 30A charger if we could do it again. Doing so would make our electric system more resilient during the winter season and consecutive cloudy days.
Download our FREE PDF to help build your van's electrical system; from batteries, to solar, to inverter, and more. 38+ pages of detailed diagrams, product recommendations, and links to additional resources.
Connect DC-DC Charger To Starter Battery
The first step to installing a DC-DC charger in a camper van is to connect the charger to the vehicle’s starting battery. Other than the charger, you will need the following products.
- Red & Black 6 AWG Wire – These 6 AWG wires will safely handle the current when connected to Victron 30A DC-DC charger.
- 60A ANL Fuse – Protects the 6 AWG wire and downstream devices from over-current situations.
- Copper Lugs (6 AWG & 3/8″) – Connects the 6 AWG wire to the 50A fuse and bus bars.
Recommended wire size for DC-DC chargers installation.
The products we recommend above are appropriately sized for both Victron’s 18A and 30A chargers.
Step-By-Step Instructions
- With 6AWG black wire, connect one end to the vehicle starter battery and the other end to the negative input terminal.
- With 6AWG red wire, connect one end to the vehicle starter battery and the other end to the 50A fuse.
- Connect the 60A fuse to DC charger’s positive input terminal with 6AWG red wire.
Connect DC-DC Charger TO Leisure Batteries
The second step is to connect the DC-DC charger to the leisure batteries. If you follow our electrical guide, you will know that we prefer to connect all our devices, including the DC-DC charger, to ‘bus bars’ instead of directly to the batteries. This helps to keep our camper electrical system clean and orderly.
By the way, if you haven’t already, you should absolutely pick up a pair of bus bars. They make the entire wiring process easier and cleaner. This is because instead of wiring every single device (like inverters, solar charge controllers, and 12V panels) directly to the batteries, you just connect them to the bus bars instead.
Bus bars are power distribution centers that collect and distribute electricity to/from multiple sources. They simplify the wiring process and help keep electric wiring clean and orderly. Connects to batteries, solar charger, inverter, and DC-DC charger.
The materials you need to complete this wiring section will be exactly the same as the items in the previous step. So you can refer to the product table above to find the items,
Step-By-Step Instructions
- With 6AWG black wire, connect the charger’s negative output terminal to the bus bar.
- With 6AWG red wire, connect the charger’s positive output terminal to the 60A fuse.
- With 6AWG red wire, connect the 60A fuse to the bus bar.
Completed DC-DC Charger Installation Diagram
When completed, the finished result should look something like the DC-DC installation diagram below.
Required Tools To Install A DC-DC Charger In A Camper Van
There are only three tools we recommend to help you install a DC-DC charger in your camper.
- Wire Stripper – Cuts the 6 AWG wire to your desired length and strips away the protective jacket.
- Hydraulic Lug Crimper – Crimps the copper lugs onto the 6 AWG wire. The hydraulic version is much better than the cheaper hammer crimper.
- Heat Gun – Activates the heat shrink over the copper lugs and wire.
This is the tool we wish we had for our build. This hydraulic crimper makes high quality, strong copper lug crimps every time (we can't say the same about the cheaper hammer crimper). Works on lugs from 2/0AWG down to 12AWG.
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Why We Recommend Victron Orion DC-DC Chargers
Victron products have a reputation for being pricier than competitor products but there’s a reason why they are the preferred brand among the camper van and RV communities. High-quality build, responsive customer service, and Bluetooth connectivity (to their Victron Connect app), makes all Victron products an obvious choice.
With the Bluetooth-enabled Victron Orion DC-DC charger, you can easily connect to the device through Victron’s smartphone app. This makes monitoring your leisure battery charging easy. Additionally, through the Victron app, you can easily change any settings of the DC-DC charger to better fit your battery’s charge profile needs.
Below are the most popular Victron DC-DC chargers. (The first listed voltage corresponds to your starter battery, the second corresponds to your leisure battery)
DC-DC Charger | Buy Wire |
12V/12V - 18A | |
12V/12V - 30A | |
12V/24V - 10A | |
12V/24V 15A |
Conclusion
We hope you found this DC-DC charger installation guide useful. As we mentioned in the introduction, the ability to charge your leisure batteries while driving is an important feature for all campers to have. This ensures you have a backup plan in case your solar panels can’t adequately charge your house batteries.
If you have any questions related to wiring a DC-DC charger in your van conversion, please don’t hesitate to reach out through our contact form.
Happy building!
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