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A Super Simple AWESOME Off Grid 12V System... Step By Step With Diagrams PART 3

Updated: Jun 19, 2022

Hi everybody and welcome to PART 3 of our awesome set up, if you are just joining us at PART 3 and have not seen PART 1 or PART 2 of our post yet please follow the links below to so you can see how we got to this point.

if you have already read the previous posts and are already caught up we are just going to jump straight back into it.

At the end of PART 2 we had just finished filling one side of your blade fuse box and you should be left with a set up looking something like this...

To make things easier again we are going to zoom back into the fuse box so we can finish wiring our accessories to it...

The next thing that pretty much everybody wants in their campers is a powered roof fan.

Roof fans are very important in a van build for ventilation, fresh air, extracting smells & fumes and with some adding a little bit of day light for the day times, there are a few good ones on the market but (in our opinion) the best one and our suggestion for this build is the Maxxair Delux.

Not only are these fans unique in the fact they have a built in rain cover so they can still be used in the rain but they also are one of the only fans on the market that can both extract and blow.

They do have a downside though they stick up quite high so if you are trying to be stealth this fan probably isn't for you.

Maxxair Maxxfan Deluxe 400 × 400 Rooflight Clear Tint Remote Control Rooflight

These are very easy to hook up and you already have everything you need to do it.

So first find your 21 amp twin core cable and run a length long enough to reach from your 12 way fuse box to your roof fan, at the fuse box end attach two ring crimp connectors and connect the negative (black) cable to any negative terminal on your fuse box and the positive (red) cable to any positive terminal on your fuse box.

Please see picture below...

Next at the fan end of the twin core cable attach one of these to the both the positive (red) cable and negative (black) cable and crimp into place... see pictures below.

Now you are going to have to connect the cables from the roof fan to your cable and to do that you are going to need to know which cable is positive and which cable is negative.

Just to make things a little bit more complicated the cables coming out of your Maxxair fan will not be black and red they will be black and white, common sense will tell you that black is negative as it has been for everything else so far but with this accessory it is not the case.

When it comes wiring your Maxxair fan black is positive and white is negative, as the background for the wiring diagram is also white for the sake of the wiring diagram this cable will be Green...

please see picture below...

Again the last thing you will need to finish the circuit is a fuse

Maxxair fans are built for 12v set ups so we don't really need to do any maths to work out how many amps these will pull as the they already tell you in amps

Set on the highest fan speed the Maxxair fan draws a maximum of 5 amps and the cable we have use is 21 amp so for this set up we are going to use a 10 amp fuse.

Once you have inserted your 10 amp fuse into your 6 way blade fuse box you should have something that looks like this.

Please see picture below...

The next thing we are going to add to the set up is a kitchen tap, a pump for your water and and a gas hob that needs to be wired to the fuse box for the spark/ignition.

Before we do that though we would just like to tell you that we have our very own Van Build facebook group where we share lots of our awesome content, exclusive content and starting this week video content too as well as answering any questions you might have for us. Please click the photo below and join our van build group if it sounds like something that interests you...

When it comes to kitchen sinks there are loads of options out there and you can even make your own out of an old mixing bowl and some decretive piping if that's what floats your boat or you are going for the homemade rustic look.

This is not what we are going to suggest though as the title of the post contains the word SIMPLE and what we just described above is far from.

So for this build to keep things as simple as possible we are going to suggest a Dometic all in one unit and not only is it an all in one sink set up is also has a double hob too 🦜🦜💎 (2 birds 1 stone)

There are a few bits and pieces you will need...

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DOMETIC HSG 2370 Litre Two-Burner Hob and Sink Combination with Glass Lid, 900 x 370 mm

Comet Cold Water Tap 12V Micro Switch Fits Smev Sinks Caravan Motorhome Boat

Whale GP1352 Standard 12V Submersible Electric Pump-White, 13 litres

Everything else you need to wire these bits and pieces to your fuse box you should already have from before. you might be running low on twin core 21 amp cable though so you might need some more of that.

*21 AMP Rated* 1.5mm2 Thin Wall 2 Twin Core Cable Wire Car LED Lights (30M Roll)

Again these are very simple to wire together but you wouldn't think it by looking at it and just to make things even more confusing they all come with different coloured positive and negative cable.

But as I said it is very simple and this is how we do it.

First run 2 x lengths of the twin core 21 amp cable from your 12 way fuse box to your kitchen area then just like before attach some ring crimp connectors to the ends of both the positive (red) and negative (black) cables on each. Next attach each the positive cables to one of the remaining positive terminals and the negative cables to one of the remaining negative terminals on your 12 way blade fuse box.

One of these cables will be for your pump & tap and the other one will be for your hob ignition.

Next find 3 x Wago 221 connectors with 2 x terminals, you should have some of these from the pack we recommended ear.lier in the post.. Please see picture below

Attach your tap to your sink and run the BLACK cable from the tap to one of your Wago 221 connectors.

Next find your pump and attach the BROWN cable to the same Wago 221 connector... please see picture below.

Now take the BLUE cable from the the pump and the Negative (BLACK) cable from one of the twin core cables running from your fuse box and attach them to another Wago 221 connector

And finally take the BROWN cable from the tap and the positive (RED) cable the same twin core cable and attach them to a third Wago 221 connector.

You should have something that looks like this...

To finish off this circuit all you now is another blade fuse, without going into all the boring maths again for this circuit we are going to use another 10 amp fuse.

Next take the remaining length of twin core that you ran from your fuse box to your kitchen area and crimp one of these connectors on both the positive (red) and negative (black) cables... please see picture below.

The cables that come from the hob ignition will be red and black so all we need to do now is crimp the positive (red) cables together and the negative (black) cables together...

And finally to finish off this circuit and your 12 way fuse box you will need another blade fuse.

The ignition will use hardly any power at all and only for a short amount of time so for this we will use a 5 amp fuse

You should now have something that looks like this...

Ok so that is pretty much all of the basics we need running to the fuse box, there are a lot more things we could add to the set up but we want to keep this set up as simple as possible so for now this is where we are going to leave the fuse box.

We have left 3 x spare terminals on the fuse box and these will come in handy if you wanted to add any extra bits to your set up for example another set of sockets, a 2nd roof fan of maybe just an extractor fan for your bathroom area. Obviously everybody's needs are different so the free space on the fusebox will allow you to add your own specific bits and pieces.

For some ideas of what you can add please check out our 12v upgrades post by following the link below...

Ok so now you should have something that looks something like this...

The next thing we are going to add to this set up is another essential for most campervans and that is a diesel heater.

Diesel heaters are literally a game changer and allow you to enjoy and be comfortable in your van all year round instead of just in the summer and even better than that they are cheap to buy, cheap to run and easy to install yourself at home. Who could ask for more.

We're not going to go into all the details about fitting them as we already have a full post dedicated to that so if you want to check that out please click the photo below.

What we will go into in this post is wiring your heater up once you have followed the fitting instructions (we cover it in the fitting instructions post too)

So the first thing we need to say about these heaters is they need to be wired directly to your positive and negative bus bars and not the fuse box. In fact you are meant to wire it directly to the battery via the inline fuse however because of our SOC shunt that we fitted very early on in the build we have effectively just moved the battery terminals to after the shunt in the form of a bus bar so it is the same thing. We can only do this because we used really thick cables at the start of the set up.

If you wire it to the fuse box you are quite likely to get some volt drop and error codes on the heater and you don't want that.

If your heater is further away from your bus bars than the power cable supplied with the heater you need to up the size of the cable or again you will get volt drop. To extend the cable any distance it is best to use 6mm2 cable.



The negative cable supplied with a heater is very short and the instructions for the heater to you to earth it to your chassis. We can't do that as we need it to run through our SOC shunt so we can accurately monitor the battery so you will need some of this



And if you do need to extend your power cable you will need the inline fuse as close to the battery (bus bar) as possible so you will need to cut off the inline fuse provided and add one closer to the bus bar...

In-Line Car ATC/ATO Blade Fuse Holder Waterproof 10AWG


So once your heater is fitted and the wiring loom is connected to the heater, controller and pump it is very simple to wire up.

First we need to run the negative (black) cable from the heater to the same bus bar that we attached our fuse box to. For this you are going to need to extend the short cable provided.

So find your 6mm2 black cable and remove enough insulation from one end to connect a crimp connector.

Please see picture below...

Next find one of these crimp connectors in your crimp connector pack

Next simply crimp one end of the connector onto the negative (black) cable that is attached to your heater wiring loom and the other end on to the end of your 6mm2 cable that you stripped the insulation from.

Now you have a long enough cable run it to the negative bus bar that you connected your fuse box to and cut any excess cable off.

Strip some insulation off of the end and attach one of these crimp connectors from your selection box...

Once you have done that connect the ring crimp connector to any spare terminal on your bus bar.

Please see picture below...

As with everything else in this set up it is best to keep your cable lengths as short as possible, our pictures are not to scale to make them easier to understand

Next find the positive (red) cable attached to your wiring loom (This should have an inline fuse built into it) and crimp the same ring crimp connector to it that you connected to your negative cable (yellow with a 8mm hole) on to the end.

And finally run it to the same positive bus bar that you connected your fuse box to and bolt it onto any of the spare terminals. You should now have a fully powered heater and a set up that looks something like this.

We are getting very close to finishing this set up now but there are a few more bits and pieces we would like to add to the set up.

The first is a decent way to charge laptops etc as they are pretty much a necessity nowadays every camper should have the ability to charge them.

We have actually just posted a BRAND NEW post on charging your laptop in a van if you want to check it out for more details and options please click the photo below...

So without going into all the details we did in the above post we have a couple of options for you and we will start with the easiest as we have already set everything up for it.

When we installed the lighter socket to your socket panel we went for a heavy duty socket for reasons just like this. We even gave an example on what you could run from that socket. This is what we wrote

"So as we said above the lighter socket you have just added to this panel is 30 amp so 2 x more powerful than the lighter sockets you installed for your fridge and TV. Although most 12v accessories with a cigarette lighter plug on them like your TV or fridge work perfectly well in a 10 or 15 amp socket some things that you might want to plug into them will be too powerful and blow your fuses or might work but not very well... for example a 300w inverter running a 300w accessory plugged into a 10 amp lighter socket the fuse would blow in no time at all, simple maths tells us that.

300w ÷ 12v = 25 amps"

Don't forget though thats 25 amps at the full 300w - laptop chargers are roughly 80w so it would be more like 5 amps when you are charging a laptop. we have fused high enough incase you do want to use it to it's full capacity for any reason. We don't like fires!

So with that being said the easiest way to charge your laptop in your van requires no extra hard wiring at all as the plug is already installed so you just need an awesome little low powered inverter like the one we recommend...

BESTEK 300W Pure Sine Wave Power Inverter DC 12V to AC 230V 240V with 4.8A Dual Smart USB Ports Car Adapter

These are great little inverters and work perfectly however as with all things with a lighter socket attachment it is very easy to keep nocking them out accidentally so if you are going to use it quite often we recommend our next option and to hard wire it to the your bus bars, we can afford to go slightly higher powered with this method too as we are not limited to the amount of amps we can run through a socket or a fuse box

BESTEK 500W Pure Sine Wave Power Inverter DC 12V to AC 230V 240V with 4.2A Dual Smart USB Ports Car Adapter

Before we go any further we need to point out this is a low powered inverter that we have added specifically for laptops. It won't work on high powered accessories and will blow fuses if you try to plug anything high powered into it.

To wire this up you are going to need a few more bits and pieces...

All Trade Direct 1M Metre Red Battery Starter 16Mm Cable Kit Car Van Truck Marine 110A 110 Amps


All Trade Direct 1M Metre Black Battery Starter 16Mm Cable Kit Car Van Truck Marine 110A


All Trade Direct 1 X Strip Link & Midi Fuse Holder


All Trade Direct 2 X 50 Amp Midi Fuse High Current All Midi Amps 40-150Amp & Fuseholder Stocked


Kohree Master Switch Battery Disconnect Isolator Switch


First take your 1 x meter of negative (black) 16mm2 cable and strip enough insulation off of each end to fit a lug.

Take 2 x 16mm2 M8 (8mm) lugs (you should have some of these left over from earlier) and securely crimp one onto each end of your negative (black) cable.

Next bolt one end of the cable to the negative (black) terminal on your inverter and the other end to the same negative bus bar that you wired your fuse box and diesel heater to.

Please see picture below...

Next take your 1 x meter of positive (red) 16mm2 cable and cut yourself 2 x 20 lengths.

On the fist length attach a 16mm2 M8 (8mm) lug on to one end and a 16mm2 M6 (6mm) lug on to the other end the securely crimp into both place

On the second length attach a 16mm2 M6 (6mm) lug on to one end and a 16mm2 M10 (10mm) lug on to the other end and securely crimp both into place.

Please see picture below...

Next put your 50 amp midi fuse into a midi fuse holder and attach the M6 (6mm) lug from each cable to either end on the midi fuse holder.

Please see picture below... (pay no attention to the cable lengths in the picture below they should be equal 20cm lengths)

Now take the end with the M8 (8mm) lug on the end of it and bolt it directly to the spare terminal on the same positive bus bar that you wired your fuse box and diesel heater to

Please see picture below...

Next find your isolator switch and attach the M10 (10mm) lug on the cable coming from your midi fuse to either of the terminals and securely bolt into place.

Please see picture below...

As you started with 1 x meter of 16mm2 positive (red) cable and cut 2 x 20 cm lengths off you should have a 60 cm length left over.

Take that 60cm length and on one end attach a 16mm2 M10 (10mm lug on to one end and a 16mm2 M8 (8mm) lug on to the other end and securely crimp both into place.

Fist attach the M10 (10mm) lug on to the last remaining terminal on the back of your isolator switch and bolt into place.

Please see picture below...

Next take the M8 (8mm) lug and attach it to the positive (red) terminal on your inverter and you are all done.

Please see picture below...

Congratulations you have now finished all the wiring in your Super Simple AWESOME Off Grid 12V System 🥳🥳🥳

And I am sure you will all agree it is awesome and very simple to install yourself.

Were not quite finished yet as we have one more thing we want to add to the set up to make it even more awesome and that is WIFI

As we installed. a smart TV in this set up and pretty much everything else in the world these days revolves around the internet it would be a pretty good idea to add it to your van. Don't worry it is very simple.

So the first thing you are going to need for this is an unlimited data contract, pretty much every network provider out there offer an unlimited data sim only deal for roughly £20 a month give or take so just choose your favourite network.

The reason we need a separate sim instead of just tethering to your smart phone is we are going to add an external antenna to get better reception and phones don't have antenna points

For more info on how to get a sim only contract check out this post...

So the first thing you are going to need is a MIFI router with external antenna ports and for this we recommend our favourite one.

NETGEAR Nighthawk M1 Mobile 4G Router With Sim Slot Unlocked MR1100 - Download Speeds of up to 1 Gbps | WiFi Connect Up to 20 Devices

These MIFI units are really good, capable of very fast speeds, have a built in battery incase you want to take it out with you and connect to up to 20 devices at once.

And because you will be in the back of a van where the signal will never be great the best thing to do is get a 4G antenna to put on your roof where the signal will be a lot better.

For this we are going to suggest this awesome antenna that is specifically designed for vehicles and made by our favourite antenna brand Poynting

LTE MiMo PUCK style antenna, white

These antennas are perfect for vanlife, as I said above they are made specially for vehicles and marine applications so they are omni directional. This means they do not need to know what direction the closest transmitter is.

They work really well too unlike some of the cheaper brands on the market.

They are 5G ready and work really well in most locations and best of all they are relatively stealth unlike other antennas that we love from the same company. Basically these are a winner.

And then finally you will need some adapters for the cables so they have the right end to plug into your router and for that you will need some of these

Eightwood 4G Antenna SMA to TS9 Cable 4G LTE Antenna Extension Cable

Installing your WIFI is very easy, you already have a USB -A socket you can plug it into when you need to charge it but it has a built in battery so does not need to be on charge all the time.

So first install your antenna on your roof and run the cables to the router through the roof to where your router is located.

You then screw the gold male threaded end of your cable adapters into the female threaded end of the cables coming from your antenna and you are done.

Before we post the final picture of what your set up will look like there are a few bits we missed off of the diagram. So we are going to add a Laptop next to the inverter, the diesel heater controller and the bluetooth module that comes with the Renogy MPPT controller. These were not important to the wiring diagram but are important for the final picture.

So now you have everything installed you should now have something that looks like this...

OK so that is it we have finished and that is our full Super Simple AWESOME Off Grid 12V System... Step By Step With Diagrams

We hope you all have found it useful and liked it, as we mentioned earlier on in the post we have also left you some room to add a few extra bits if you wanted to customise it or add anything you might need that we have missed off of the list.

If you are looking to add anything and wan some links to some cool bits and pieces please check out some of our other posts. We have linked to some of our most popular posts lower down the page if you keep scrolling

Thanks for reading




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