Install A DC-DC Battery Charger. We have already installed a simple battery isolator to keep our auxiliary battery system charged while we finished other parts of our build before the summer season started. This low budget option works, but it is time to upgrade and install a DC-DC Charger in our Van.
Install A DC-DC Battery Charger
Something that was clearly noticeable with only a battery isolator was that the battery was not getting a full charge, no matter how long the engine was running.
Shore Charge VS Alternator Charge
Shortly after shutting the engine off, we would watch the voltage go from 14v down to 12.9v. Then with just a small load the voltage quickly would drop lower. We compared this to a wall charger to see the battery hold at 13.0V for a long while before dropping to 12.9V. This test confirmed our suspicions that our battery was being undercharged.
So even though the auxiliary battery isolator worked,(kind of) we needed to get a full charge into the battery to lengthen it’s lifespan as well as give us more usable Amp Hours.
Choosing A DC to DC Charger To Suit Our Requirements
Originally, we wanted a dual-input DC to DC charger with Solar MPPT, we had our sights set on the Renogy DCC50S 12V 50A DC On-Board Charger with MPPT. Unfortunately, all in one DC-DC, solar chargers were a little above our current affordability. With that in mind, we decided to split up the cost by installing the DC to DC Charger in the van first and adding solar at a later date.
Enter the Renogy 12V DC to DC On-Board Battery Charger
Browsing Amazon, I came across the 20amp version of Renogy’s 12V DC to DC On-Board Battery Charger for $139 CAD, I was soon sold! Our power needs are small, and we will be supplementing with solar in the future, so why not give it a go. 
Now Let’s Take A Closer Look At How We Installed The Renogy 12V DC to DC On-Board Battery Charger In Our Weekender Van Life Ram ProMaster Campervan Conversion
Installing A DC-DC Battery Charger In Our Van – How We Did It
Tools and Materials
- Renogy’s 12V DC to DC On-Board Battery Charger
- 6 Gauge Ring Terminals
- Heat Shrink
- Split Loom Flex
- ¼ 20×1/2” Machine Screws
- ¼ 20 Lock Nuts
- Rubber Splicing Tape
- Vinyl Insulation Tape
- Crimp Tool
Step-1 Inspect The Goods
Straight out of the box, a quick look at the battery charger reviled a questionable burn mark on the power terminal! Could this mean the unit is second hand and had been installed previously, I’m not sure? We kept going with the install so we could test it out.
Step-2 Reroute Aux Power Supply / DC-DC Battery Charger Install Wiring Diagram
We have already run the auxiliary power supply from the vans factory upfitter connection, now we just needed to adjust our wiring to work with the new DC-DC Battery Charger Install.
Step-3 Build Backer Panel
To avoid screwing into our nice wall panels, we used a piece of plywood as a Backer Panel. We didn’t have any stain left and couldn’t go to the store (Covid19) so we wrapped the wood in Extra Wide Vinyl Electrical Tape.
Step-4 Main Wire Connections
Next, we spliced the wires using ring terminals and ¼” bolts with locknuts. Wrapping them with rubber splicing tape to finish.
Step-5 D+ Wire / Ignition Power
The Renogy 12V DC to DC On-Board Battery Charger needs a positive feed, energized when the vehicle engine is running. This prevents the charger from operating when the engine is off. Because we already have a battery isolator, I just fed this from the supply side of the charger.
Step-6 Test And Charge!
Green means go, Works like a dream! 
DC-DC Van Battery Charger Installed And Working
The only real load on our battery bank is our small Dometic fridge, and we are not currently leaving operating full time. so far a short drive each day seems to be keeping the battery bank topped up. Time will tell if the 20amp model will be enough. We are optimistic🤞
Here Are Some Related Posts You Might Be Interested In
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More Interesting Articles To Check Out
- DIY Portable Solar Generator
- Renogy 500A 12V Battery Monitor Install
- Camper Van Fridge Installation
- Van Electrical System
Lastly, if you have any questions, post a comment below, we would be happy to help.
Thanks for reading, and remember to always take the road less traveled!
Hi, Did you connect the ignition signal wire to your DCDC charger? Can this Dcdc charger work as normal without connect the ignition wire?
The photo of the seat box. What are you connecting the ground wire too?
That photo isn’t the best
Hi Jason,
You may want to check out our van battery isolator installation It shows how we tap into the 70 Amp Up Fitter Power Connection
I am contemplating installing the 20 amp dc to dc charger in my minivan. How did yours work out for you?
Hi Steve,
So far we are very happy with the 20 Amp. My van is my only vehicle and it gets driven multiple times a day, if this weren’t the case I may think about going with the bigger model.
With our low power use and regular charge periods, it is working great.
Hi did you put a fuse in the d+ ignition side of things thanks
Hello,
I just purchased a promaster not long ago and have been reading all over the place about doing a dc to dc charging system. I like how simple your system is to start out. Since it’s been a few months since you have done this has it worked out well keeping your Aux battery charged ? And how much usage are you Using vs how much is it charging?
Thank you!