Basic 12V system review

[RacingSlow]

Hi Guys,

I have started building a basic 12V system for my van centred around a roamer230SB. I installed the below yesterday.



I have since been made aware that i require a new fuse directly on the battery terminal, for this, i plan to add a 100A MRBF fuse before using the battery.

I also plan on adding a 50A DC-DC charger in the near future, i have included this in the diagram below with the addition of the MRBF fuse.



I'd welcome any feedback on the above! I think the main bit that i'm unsure on would be how large the MRBF should be, especially once DC/DC is in.

 

[Dellmassive]

Nice, the fuse rating is dependent on the cable gauge.

Can you add in the cable sizes?

 

[Sim60]

You probably need to fuse both ends of the DC-DC to Roamer depending on cable length.
The minimum is a fuse at the Roamer end.
Also, if you’re fitting a 100A MRBF fuse, then the cable to fuse box needs to be rated at 120A+

Each fuse needs to be lower than the rating of the cable its protecting

Simon

 

[RacingSlow]

Hi Both,

Thanks for the feedback. Wire sizing is a very good point, can you tell it was 1am?

Please see below an updated example. Its a mix of 16mm and 3mm as its on hand.

 

[Dellmassive]

First thing...
This fuse needs to be at the battery end of that cable.

"All battery connections need to be fused"

 

[Dellmassive]

The dc-,DC input NEG does not need to go back to the starter battery, just give it a chassis ground.

 

[Dellmassive]

Dcdc output NEG does not need to go direct to the battery.

It can go direct to chassis...

Either or. Whatever is shortest.

 

[Dellmassive]

I wouldn't pull more that 50A over a 16mm2 cable.

So maybe drop your 100A fuse down to 50A from the Roamer.

3mm2 cable for the 12v socket is a bit small if you plan on pulling the 100w+ 15A that some devices will draw, IE tyre pump or laptop charger.

Same with the fridge..... I'd beef up the fridge feed cables.

 

[Dellmassive]

Thread 'Diagrams, Schematics & Wires -- How I Done It --'

27 Dec 2019

Diagrams, Schematics & Wires -- How I Done It --


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Dellmassive`s -- "how I Done It" -- Thread
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Kit List And Stuff -- How I Done It & What I Use --
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This is a handy place to post my -- How I Done It -- Diagrams and schematics etc.


To start thing off here is todays diagram,


Using speaker ISO connectors and breakout loom:



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• Dellmassive
• ambient lighting wiring wiring diagram
• Replies: 128
• Forum: Electrics, Lighting, ICE, Security

• 

 

[Dellmassive]

Fridge....

We used 6mm2 here.

Post in thread 'Diagrams, Schematics & Wires -- How I Done It --'

25 Jan 2020

Leisure Battery & Fridge:

• Dellmassive

• 

 

[Salty Spuds]

A 100A fuse is a bit of a jack of all trades master of none. 100A is way too big for your average simple installation, fridge, lights, heater, USB. As @Dellmassive says, 50A is plenty. On the flip side, 100A (and associated cabling) isn’t big enough to run a decent sized inverter.
Add up your total maximum power usage, add 10-20%, size your cables accordingly and away you go.

 

[RacingSlow]

Thanks so much for the feedback all!

I'm hoping to get away without an inverter. The biggest thing that i should need to power will be my laptop. For this i plan to use one of the 12v 100w chargers. This should be around 10A. I have upgraded to 6mm here, along with the fridge. I have also brought the fuse down to 50A.