[Guide] DC-DC Charger (for leisure battery) -- How I Done It --
- Thread starter Dellmassive
- Start date
Hi Dell question as I got similar set up with factory battery and hoping to reuse as you mention in post. Removing relay etc. I assume the original wiring its ok for victron Orion xs as you already swapped few different dc dc chargers there and newer mentioned about wires, my question its what if I need move charger away from seat as inverter too big and need get under bad next to wheel arch. Does that wire would be still ok or should I fit new one bigger size? It says 16mm under 5m but no clue how long wire it’s up to seat. And ideas please let me know and thank you, I try learn as much as possible from you postsPart2 added, part3 to come . . . . . . .
Part3 is more about the install,
once you have decided on what unit you want to go for, its time to get it fitted.
Now even though i have the BCDC1240 which has built in solar MTTP i chose to go with a seperate Victron MPPT and just run them side by side.
Now you have a few options: If you have the factory fitted leisure battery or not?
If you have the Factory fitted kit then VW will have done all the hard work for you and run all the cables, fitted fuses etc . . . the even give you a nice ignition/engine run wire. (which is nice)
Vw fit a SCR like this : (this is under the front seat (double bench in my case)
This needs to be removed and replaced with your shiny new DC-DC charger.
They will also have fitted a second battery for you: again here under the double bench:
Now at this point depending on the Amp rating of your new DC-DC you may be able to just replace the relay with this mod from @travelvolts https://www.travelvolts.net/product-page/plug-and-play-upgrade
View attachment 52401
Which make the install plug-n-play and leaves the original factory setup in place.
If not then you can do as i done and just cut out the factory supply fuse and relay and replace it with your own . . . . i went for MIDI style fuse holders and crimps.
I also chose to add some battery monitors at the same time . . . at this point it was a couple of BM2 battery monitors . . . . like these :
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Because i had the factory wiring, the link to the starter battery was already in place and fused,
the link to the AUX battery was there and fused,
The ignition feed wire was already there,
all i needed to add was a new ground cable for the DC-DC.
i used velcro to stick the DC-DC to the seat basr, and made all the connections with MIDI fuses and crimps.
I also decided to fit a new fusebox to the AUX battery at the same time . . .
once complete i used the BM2 battery monitor to keep an eye on the performsnce of the new DC-DC charger . . . as we can see here it works perfectly (on the EFB+ AUX battery)
it also worked great as a jumpstart for a dead AGM battery when camping charging the battery at the full 40Amps with the engine running. see here > Mobile Solar Panels ? . . . - How I Did It -
and some final battery testing . . .
.
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more in part 4
That's a much longer run and so you'll get more voltage drop, and more heat so I'd personally want to increase the size.
I'm using an Orion XS with the standard factory wiring and it's been perfectly fine, but mine is under the passenger seat.
Dang that’s what I did planning to do but with moving all away I might consider run 25mm then. Or might run 16 from seat then test run with thermal camera and heavy load to see if cable getting too hot or it’s ok 
Same as me. I used as much of the original installation under the passenger seat as I could. I replaced the VW split charge relay with a fabricated box that fitted into the space left and that clipped in using the same attachment method. Inside this box is a midi fuse holder with a 60A fuse that allowed me to use the original VW vehicle battery cable and crimped tag (with an M6 hole) to connect via it to the Orion XS’s Vehicle Battery terminal. I also modified the battery +ve connection (drilling out the rivet holding the 200A fuse and replacing it with an M5 bolt) to allow a 60A midi fuse to be fitted (shown in second picture).
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Trying to get my head around lol
I might give up on spit charge wire as it’s only 16mm but I find there 25mm for jump charger from engine as show on ex rac diagram next to side door
Wonder if keep any of wiring for lights etc or just do new new hmmmm
I might give up on spit charge wire as it’s only 16mm but I find there 25mm for jump charger from engine as show on ex rac diagram next to side door
Wonder if keep any of wiring for lights etc or just do new new hmmmm
jgm0
Member
Hey @Dellmassive I'm using this as A guide and I'm about to start my installation. I have the factory Aux setup under the passenger seat. I'm going to use the existing wiring from my engine battery into the MPPT/DCDC controller. Do I also need to run a new negative cable from the controller all the way back to the engine battery? Or is it already wired up and grounded to the chassis somewhere? cheers
Your leisure battery will have an OEM ground cable that's connected direct to the chassis next to the battery.
You can connect your dcdc charger to either the leisure battery negative or a negative bus bar or the chassis connection.
Make sure that the cable is the same thickness as the incoming power and that is fused correctly.
The OEM setup on my van had a 100 amp relay and was fused down to 80 amp from memory.
But I would say around 30 amp is the sweet spot. So set the dcdc charger for 30 amp maximum fuse the cable at 50 amp assuming it's thick enough cable... The OEM cable normally comes from the SA fuse box under the battery and is 100 amp fused.
As you say there is two domed knuckstuds underneath the carpet in the middle of each seat base..
These can be used as an egg chassis connection for batteries they say DC chargers neg bus bars. Etc etc.
If you need a higher power connection you can use the seatbase bolt, provided that you clear off all of the paint so you have a good metal to metal connection.
jgm0
Member
Cheers @Dellmassive – I'm getting rid of the factory aux/leisure battery and relocating everything under the driver seat with a new 100ah lithium. Hoping the factory wires are long enough to fish under the carpet. I will extend the factory engine battery pos cable and add a 40amp fuse before it goes into the dcdc.
I'll be using 25mm² cable as the biggest coming from battery to switch and then for the main earth which will go to a neg bus bar, then I'll connect the dcdc and all my other negs to that. So is it ok to just snip off the OEM ground cable?
Thinking the seat base bolt will be the best negative so will take out a bold a sand it down to metal.
Do you know which cable is the ignition feed in this factory setup? I need to get that to my mppt/dcdc as well.
First time dabbling with electrics so its a lot to take in! Appreciate your help
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