Van Conversion # 7 – The electrical system

Pé na estrada! (2)

First of all, it is important to say that everything that follows was written by us, people with electricity experience equal to 0 before we converted the van.

Before we start doing the electrical system we read a lot, we saw photos and videos and we feel confident we can do this for ourselves, but do not take what is written here as 100% sure, because as we said we have practically no experience.

Electricity is a serious issue, as poorly wired wires can cause short circuits, melt, cause fires, so it is always advisable for someone with experience to do something like this.

electrical stuff

1 – Wire 25mm2 (6 meters) / 2 – Wire 6mm2 (6 meters) / 3 – Wire 0.75mm2 – (10metros) /4-Wire juctions /5- 750W convertor / 6V 6– Bar for the negatives / 7 – Junctions for Wire 6mm2 / 8 – Gas Detector / 9 – Solar Panel Controller / 10 – Voltmeter Monitor / 11 – Battery Terminals / 12  Fuse Box- 13 – Main switch / 14 – 80 Amperes / 15 fuses – Led lights 5 wx 8/16 – Junction box for wires / 17 – USB sockets (12v) / 18 – Switches x7 / 19 Light regulator / 20 – Fuses 5-35 Amperes

Up here is the list of just about everything we used at the level of electricity in the van, we just lack the relay that allows to charge the second battery through the movement of the van, the battery, the solar panel and some smaller things.

How much energy do we need?

Before you start thinking about the electrical system you need to realize how much energy you need, and think whether or not it’s worth putting up 2 solar panels or having two batteries.

In our case our big energy consumer will be the refrigerator, which will consume about 20 Amperes per day, then it will be basically the lighting, some electric kitchen appliance that we use and carry the mobile phones, photographic machine, computer …

So we think that a battery of 100 Amperes (attention that should only use up to 50% of the capacities of the batteries, so we can only use 50 Amperes) was fine.

Our battery will charge in two ways, through the solar panel (100w), or through the movement of the van (a reley attached to the main battery). As Portugal has many hours of sun a year, and we intend to make km with the van, we think that it will suffice the 100w of panel and of 100Amp of storage.

For countries with less sun it would be complicated to have the system that we have with only a 100w (solar) / 100amp (battery).


Our battery is an AGM 100 Ampers.

We chose this battery because it can be used in any position, it can withstand “deep cycles”, even though the use of more than 50% of the capacity of the battery decreases the life time, it is heavy but not too bulky and in case of accident it does not spill acid.

At the end of the article we will leave some links to things that we read that have helped us to make this decision and for you to take yours as well. But for us this battery offers the best quality / price / duration ratio.

The battery cost € 180.

painel Solar

Our solar panel is a 100w monocrystalline panel. Monocrystalline panels are better than polycrystalline panels because they are more efficient compared to the area, they are more expensive but they compensate. It was 200 € with assembly, wires, controller …

For those who want to do just make a hole for the cable and fix with silicone / glue.


Here is the Diagram of our electrical system, it is important to do so in the future we can solve problems, and to know what we have done.

Pass the wires

The first thing we did was to pass a few wires before we had the structure of the bathroom and wood ceiling done.

In our case we did not have to worry too much about the wiring, since practically all electrical things are on the driver’s side of the van, and the battery is in the back of the truck, so we centralized everything and made it easier.

We used wire of 0.75mm2 (lights), 1.5mm2 (sockets, water pump), 2.5mm2 (solar panel, refrigerator), 6mm2 (everything we connected to the solar panel controller) and 25mm2 (Negative battery and converter, connecting the battery to the converter, and connecting the batteries).

We thought it best to place the wires between the vapor barrier and the wood panneling, because if we had to access them for some reason, it is much easier. We almost always used ring tube to protect the wires.

How to know which wire diameter to use ?

The thickness of the yarns varies mainly due to two factors:

  • Electric current (amps) – The more powerful the device, the thicker the wire must be. For example our refrigerator is 50w, 50 / 12v = 4.2 Amperes. (Amperes = Power / Voltage), then we need a thicker cable, especially with more insulation due to the increase in temperature caused by the electric current.
  • Wire Distance – The longer the wire, the thicker it has to be.

It is through a mathematical formula that calculates the diameter of the wire, however on the Internet there are already many websites that calculate this, just insert the data.

We used this one:

Cable size and fuse calculator

This site is good because it gives us the necessary fuse to, which will be needed a little further.

Decide where the battery and the rest of the system will be

This part was not easy because at the beginning we did not want to make the electrical system in the middle of the kitchen counter because of being near the water pipes and as everyone knows electricity + water = Problems, but we ended up doing it for lack of better options, and also because we made the kitchen sink to get the dirty water pipe to the driver’s side and because the water system was leaning against the bathroom.

At the end it was cool, simple, everything close and fit everything on the site.


Start connecting everything

In fact, the electrical system was simpler than we thought, because you just have to follow some rules like:

  • The negative of the devices goes to the floor (negative bar, screwed to the van plate).
  • Respect the signs, + .. +, -…-.
  • Connect all appliances to a fuse.

What we basically did was: all the appliances (lights, refrigerator, sockets …) have two wires, one + and one -, the – we connected directly to the chassis of the van (negative bar), and then with the + to the fuse box.

you should take off the paint for a better conection

Then we connected the fuse box to the solar panel controller. (all positive).

The controller is quite simple, has 6 inputs (+/- solar panel, +/- battery, +/- fuse box)

Then we just make the connections, on the battery + we put an 80 Amp fuse to prevent.

After the fuse we set the main switch, to turn off the system when we want.

In our case the black and the blue is the + and the brown the -.


80 Amps fuse

The fuses are what will protect the system from any short circuits, what they do is just break  before there is any problems. The fuses must be in accordance with the current that will pass through the cable.

We used fuses from 5 to 80 amps.

the converter

The converter is what will allow us to use devices that work on the 220v in our house on wheels.

In case we need the blender or to charge the computer / photo machine, everything else is a 12v.

Our converter is 750w, its works basically for everthing besides anything that invole heating / cooling. In our motorhome we had a 500w was always perfect for us .



As the converter will get relatively inaccessible to turn things on so we made an extension, which we attached to a plug on the wall of the van. It will be here that we will load our appliances at 220v.

We connected the converter to the battery through 25mm2 wire. At + we put a 80amp fuse. The negative goes to the chassis.

split charger reley

We’re still waiting for for the reley

The relay is what will allow the secondary battery to charge through the movement of the van

Price of the Materials

  • Wire 25mm2 (6 meters) – € 34.61
  • Wire 6mm2 (6 meters) – € 8.30
  • Wire 0,75mm2 – (20metros) – 9,89 €
  • Wire 1.5mm2 (30 meters) – 20 €
  • Joints for wire 1,5mm2 – 2,33 €
  • 750 W converter – 56 €
  • Bars for the negatives – 6,90 €
  • Wire Joints 6mm2 – € 1.50
  • Gas Detector – 8,10 €
  • Solar Panel Controller – 5,66 €
  • Monitor with Voltmeter – 7,32 €
  • Battery terminals – € 4.90
  • Box with assorted joints – 6 €
  • Main Switch – € 10.41
  • 80 Amp Fuses x 2 – 10 €
  • Led Lights 5 w x 10 – 29 €
  • Fuses 5-35
  • Amps – € 4.56
  • USB Sockets (12v) – € 7.27
  • Switches x7 – € 5.64
  • Regulator for lights – 8.90 €
  • Battery 100 Amperes € 180
  • Solar Panel Kit 100w – € 188
  • Eyelet for wire 25mm2 x10 – 10 €
  • 220v socket – 3 €
    Total: 627.32 €

Support material

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