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

Updated: Jun 16

Hey everybody, so we had a lot of comments that our last full system set up was a bit over the top for most peoples needs and to be fair it was all singing all dancing. Another complaint we had was that is looked really complicated however we are just going to put that down to people on facebook just looking at the post thumbnail rather than reading the post as we have been told by far more people how awesome and easy to to follow it was.

The set up was aimed at full time van lifers who wanted all of the luxuries of a home but in a van and we think we smashed it.

If you haven't seen it yet take a look it might be exactly the sort of thing you want for your van conversion, it is in four parts but all are available to see on our blog now. This is part one...

So we have decided to reply to the comments with a totally awesome but super simple fully off grid set up that we hope will be an awesome solution for many of you.

We hope you all find it helpful...

The first thing you are going to need to be off grid is somewhere to store your energy and for that we use a battery, for this set up we are going to recommend an AGM (absorbent glass mat) battery.

AGM batteries are perfect for Vans as they are sealed so there will be no dangerous fumes leaking into your van whilst you are sleeping at night.

This battery is quite expensive but literally one of the best AGM batteries on the market anywhere in the world, at its recommended 50% depth of discharge it will give you 1400 cycles (and probably a lot more).

Rolls S12-290AGM Deep Cycle Series 12 Volt Battery



As we mentioned above these batteries are quite expensive, but they are the best AGM batteries on the market in our opinion and they store about three times more power than your average leisure battery. However if this battery is too expensive for you check this post out for a few more good options...

This battery will give you 260AH @ a 20 hour rate of discharge however don't forget that you should only discharge an AGM battery to about 50% of its capacity so in actual fact this battery will give you 130AH of useable power. Please see picture below...

Leisure batteries are very easy to install and basically they just need securing into place so they do not move when you're driving and then you need to earth them somewhere on your vans chassis.

To do this you will need a cable and some lugs, when it comes to batteries that have the ability to supply very high amps all at once it is always best to be safe rather than sorry and over size your cables so they have no chance of getting hot and starting a fire.

It is also a very good idea to run the shortest length of cable possible to each and every component in your build for the same reason as above and to minimise volt drop.

With that being said to earth your battery to your chassis we recommend using 50mm2 cable.

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All Trade Direct 1M Metre Black Battery Starter 50Mm2 Cable Kit Car Van Truck Marine 240A 240 Amps



SELTERM 50 mm² M10 Hole UL Marine Grade Wire Lugs, Battery Cable Ends, Tinned Copper Eyelets, Tubular Ring Terminal Connectors [B68] - 15 Pack



Building your battery cables yourself at home will save you lots of money and is very simple to do, first you remove just enough of the cable sleeve to fit securely into you lugs. Please see picture below...

Next you need to securely crimp it into place however these things are huge and quite solid so you will need a specific tool for the job or improvise with a hammer and punch. We suggest using the correct tool for the job. Basically you put your cable and lug in it, whack it with a hammer and it is done...

Draper 64335 Battery Terminal Crimping Tool


To earth your battery bank you need to either find an earthing point that is already there or make your own, it saves a little bit of time if you already have an earthing point near where you want to install your battery bank but it only takes about a minute to make your own.

To find one that is already there you just need to find somewhere on your vans chassis that already has a bolt in it, the most common places to find them in the back of a panel van would be near your light clusters where your lights have been grounded but they are usually quite hight up.

To make your own drill a hole into a bit of your interior bodywork that is connected directly to your chassis, remove all the paint from the area around the hole with a grinder or some sand paper so it is bare metal, pop a bolt through the hole, attach the earthing cable, screw a nut onto the bolt and you are done.

So first take your 50mm2 black earth cable and securely crimp a lug to each end, then bolt one end to the negative - terminal of your battery. Next take the other end and bolt it to your chassis earthing point and you should have something that looks like this...

The next thing we are going to add to this set up is an awesome bit of technology called a SOC (state of charge) shunt that will let you accurately monitor the state of charge of your battery in a few different ways, we need to attach this to the negative battery terminal before we attach anything else so now is the perfect time to do it

For this you will need...

Renogy 500A Battery Monitor



All Trade Direct 1M Metre Black Battery Starter 50Mm2 Cable Kit Car Van Truck Marine 240A 240 Amps



Once you have the bits above you are ready to install it, so first take your 50mm2 cable and cause 30cm off of one end so you are left with two cables, one short (30cm) and one long (70cm)

Take the small 30cm length and just like before securely crimp a 50mm2 M10 cable lug to each end. You should have some of these left from the pack I recommended earlier. Please see picture below...

Next bolt one end directly to your negative terminal of your leisure battery.

please see picture below.

Once you have done that you will need to find the 500 amp shunt that will have come with your Renogy battery monitor and connect the B - (battery side) to the cable.

Please see picture below...


We got something wrong, because of something we will be adding later on in the set up we have to change the way we earth the battery and we have only realised when it was too late.

So instead of earthing your battery from the negative terminal on your battery like in the picture above. We now need to earth it via the P- (load side) of your shunt.

Please see picture below...

Next find your remaining 70cm length of 50mm2 cable and again securely crimp a 50mm2 M10 cable lug onto each end, then connect one end to the P- (load side) terminal on your SOC shunt.

Please see picture below...

To power your battery monitor and for the shunt to be able to measure how much power you are using you will now need to connect the shunt to the positive terminal on your battery, the kit comes with the correct cable with the correct size lug attached.

So find the red positive power cable that came in the kit with your battery monitor and attach the side without the lug on it to the B+ terminal on the battery side of your shunt.

Next take the end of the cable with the lug attached and bolt it directly to the positive terminal on your leisure battery.

Please see picture below...

And the final thing you will need to add to finish the shunt install is the battery monitor itself, this is pretty self explanatory really as it has a plug on each end. One connects to the controller and the other one connects to the shunt, it couldn't be simpler.

Please see picture below from Renogy...

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

For the shunt to work properly and register all of the power being supplied by your chargers or used by your accessories it is very important that everything you install to be connected to the load side of your shunt instead of directly to your battery, to do this you are going to need to use some bus bars.

Because we need to attach so many bits and pieces to the shunt it would be very hard to find a single bus bar that has a high enough amp rating with enough terminals to fit everything onto, so we will need to be a little bit creative to make sure everything has its own separate terminal.

So for this you will need...

VTE 7753N7N14 BLACK 700 Amp Super Heavy Duty 3 way bus bar 1 x M10 & 2 x M8



T Tocas 300A BusBar Box - Heavy-Duty Module Design Power Distribution Block with 4 x M8 Terminal Studs



All Trade Direct 1M Metre Black Battery Starter 35Mm Cable Kit Car Van Truck Marine 240A 240 Amps



All Trade Direct 10 Copper Tube 35Mm X 8Mm Lug Battery Starter Cable Welding Crimp Terminal Ring



Once you have all of the bits above the first thing you are going to need is your 3 way 700 amp bus bar. I know 700 amp seems a lot but that is its maximum load its nominal load is much lower making it perfect for this set up.

So take your 3 way bus bar and attach the cable that is attached to the load (P-) side of your SOC shunt to the biggest terminal (M10) and both securely into place.

Please see picture below...

Next take your 35mm2 negative (black) cable and cut off 2 x 200mm (20cm) lengths.

Take both pieces and securely crimp a 35mm2 M8 cable lug onto both ends of each cable, you should now have 2 x very short battery cables with a lug on each end.

Please see picture below...

You now need to bolt one of these cables to each of the remaining terminals on your 3 way bus bar, make sure you do it in the same direction as in the photos so the T-Shaped cover will fit on correctly.

Please see picture below...

The next step is another really easy step, you now just need to attach one of your 4 way 300 amp bus bars to each of the cables you have just fitted. They have 3 x M8 terminals and 1 x M6 terminal, you want to connect the cables to one of your M8 terminals.

Please see picture below...

Now we have finished the negative bus bars and you now have somewhere to earth everything that we are going to add to the set up so it will register on your battery monitor.

Next we are going to add some positive bus bars to the set up too to keep everything tidy, cables lengths as short as possible and so we don't have to run everything all the way back to the battery.

Just to keep things as simple as possible for everybody we are going to pretty much replicate everything above again but with a few added extras.

For this you will need...