DIY Campervan Wiring…With STRING! | Sprinter/Crafter Van Conversion

Hmm...why is our electrics not working? Could it be the string?!

Written By Freedom Strider

On June 13, 2020

Wiring freaks us out a little bit, so before we sliced up our copper and do it for real, we decided to DIY wire up our campervan safely...with string! For someone who is new to wiring, this helped us visualize our system and worked very well to help us decide the campervan's electrical system layout.

1

Obtain all electrical boxes + string

We pulled all our electronics out of their fancy packaging and put them all on a table in front of us to see what we are dealing with.

We luckily had a digital wiring diagram we had drawn earlier so we knew what should be connected to what, but now we had to figure out the most efficient way to do so, keeping weight and cable length in mind. 🔌

We connected everything up on the table, which was helpful because it was very hands on. But to finish off the planning properly, we had to take the rig into the van.

To the van! 

off-grid electrical system - victron mppt
off-grid electrical system - lithium batteries

2

First Draft

We moved everything to the van, created a cardboard box and put the batteries inside.

This box was a mockup for a plywood box which would be used to contain the batteries, and can be used to mount our other electrical boxes to the side, so they are visible and we can work on them easily. 📦

It sort of worked, and for a first draft it gave us an idea of what we wanted, although we did wire up the BMV shunt wrong and the box was quite unnecessary as we only used 2 sides, so the rest was wasted material and weight…

Back to the drawing board.

off-grid electrical system
off-grid electrical system
DC Wiring - Van Build Freebie
VAN BUILD ELECTRICS WORKSHEET – BEGINNER

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Plan your electrical wiring for your van build. Electrics are a palm-sweating, procrastination inducing thought, and starting is the hardest part.

This worksheet will help you identify the terminology you need to advance your research and explain what and why you need what you need

3

Revised model

After thinking some more, we created 2 cardboard templates for a 2 sided mount, which would house the boxes, and then created a minimal base for the batteries to sit on.

Using this, we managed to duct tape everything onto the cardboard where it needed to go and the design looked much better, so we began to string it all up. 🏷️

off-grid electrical system

TOP TIP

For our battery setup, we chose to go with Lithium batteries, instead of Lead Acid AGM’s.

We did go back and forth for a while between the two, and although Lithiums are more expensive initially, the benifits outweigh the cost, especially the weight saving and lifespan.

We compared the two batteries types in our video here. 🔋

4

DC-DC-Where?

We started with the DC-DC charger since this had wires already attached to it; best to get it out the way first.

We followed the instruction manual labeling where everything goes, and we physically attached the wires to the negative end of the BMV shunt and the positive battery terminal (with a tapped eyelet).

We only tapped them because this was a model, and if we had to get any wire extensions this was the time to figure it out, plus no electricity is running through things.

When it comes to actually wiring everything, you crimp the eyelets onto the wires, but that is permanent.

off-grid electrical system
off-grid electrical system

5

STRING

Since the rest of our boxes had no cables, instead of guessing their cable length and cutting up our expensive 16mm cable, we instead used green and brown string (+ and -) to wire up our 50A MPPT Solar Charge Controller, our 30A AC charger, our 12V fuse box, and the BMV-712 Shunt.

We ran the string as though we were running cable, tying it into place around our eyelets (where needed). We attached the string to our fuse holders, as well as a kill switch and any other small extras, but we only focused on the charging side, everything coming out the fuse box we ignored for now, as that cable length is not as vital to get the correct length.

off-grid electrical system

TOP TIP

All wiring is at least a little bit messy. We tried to organise our ‘cables’ to run intuitively to where they needed to go, and kept them as neat as it is possible to do.

We know it will never be straight lines and 90 degree angles, but it’s better to go for neat rather than end up with a mess, as it’s easier for diagnostics and repairs.

6

Measure up

Once we had everything connected and we triple checked to make sure it was all correct, we began measuring each string length between every component with a flexible tape measure. 

We noted every length down, so we know exactly what size to cut all our 16mm cable to.

This exercise not only helped us grasp what connects to where in physical form (rather than on a digital wiring diagram), and let us play around with the components, but was also a safe way to do so, since all the wires are string and no electricity will be running through them, allowing us to swap, cut and change things around without running the risk of electrocuting ourselves. ⚡

off-grid electrical system - lithium batteries
off-grid electrical system

quick look

Quick Steps Overview:

  1. Gather all electrical boxes
  2. Create a mockup
  3. Move to van, and refine mockup
  4. Use string to wire everything together
  5. Measure string lengths

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