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The vanlife => Van Conversion => Topic started by: Do224 on September 28, 2017, 02:57:40 PM

Title: My electrical system
Post by: Do224 on September 28, 2017, 02:57:40 PM
Hi all,

I'm I the process of converting my van and have reached the point where I can't ignore the electrical side of things any longer.....I'm going to have to get my head around it!

I've installed two 300 watt solar panels on the roof and wired them in parallel. I'm intending to connect them to a Victron 100v/50a MPPT charge controller. Sound OK? I'm basing this on 600w/12v=50Amps.

I'm then intending to connect the charge controller to two 220 amp hour,12 volt, fully sealed leisure batteries also wired in parallel to maintain a 12 volt output.

I've calculated the wire thicknesses needed for my appliances using the online calculator recommended by Mike, but I'm struggling to understand how to calculate the wire thickness required to connect the batteries together. Similarly what thickness of wire should I use to connect the batteries to the charge controller and the fuse board to the batteries? The charge controller I mentioned above doesn't have a 'load' connection, only connections for the solar panels and the batteries.

Cheers for your thoughts,

Title: Re: My electrical system
Post by: Camper_Dan on September 28, 2017, 10:35:50 PM
Greetings & Welcome!

While I can't claim to be an expert on solar panel installations, because I was never satisfied with any of the 3 I've had, I can perhaps help you with wire sizing rules in general.

The general rule of thumb is to size your wires one size larger than the maximum volts/amps/watts, that is going to be flowing through them.  So I would size the wire between the batteries to one size larger than what would carry 220a @ 12vdc, and from the charge controller to the batteries, I would size the wire to one size larger than 50a @ 12vdc. 

Do keep in mind that this is for short runs of wire.  For longer runs of wire, you also need to take into account the resistance added by length, and use larger wire sizes accordingly.  There should be charts online for figuring this stuff out.

Here is the chart I usually refer to:


As a side note, I would also add an isolator to charge your house batteries while driving.

Good luck, hope this helps, and keep us posted!
Title: Re: My electrical system
Post by: Do224 on September 29, 2017, 11:33:05 AM
Many thanks Dan. Just to add a little further confusion, I've just been reading up on the he charge controller I'm intending to buy and it states the terminal size to be 13mm2. https://www.enfsolar.com/pv/charge-controller-datasheet/191 here's the link. Presumably that means I can't connect a thicker wire than 13mm2. Based on your advice and a little bit more research I've done, I think that to connect the batteries to the controller I would need 16mm2 based on a 50cm run of wire or 25mm2 based on a 1 metre run......or am I missing something?


Title: Re: My electrical system
Post by: Camper_Dan on September 29, 2017, 11:35:33 PM
I hate to say this, but now I'm at a loss too.  I didn't have much luck finding a conversion of wire sizes from metric to American along with the amp ratings.

To add to this confusion, I don't know how or if their terminal size relates to actual wire size.  Supposedly that terminal is capable of passing 50amps. So according to this chart:


I would want to use the equivalent of #4 AWG wire for this.  So the question that I would have is whether the terminal connector used between the controller and the wire is capable of that size wire, and if it's conductivity rating is at least the 50 amps needed.

Hopefully this helps some...

Title: Re: My electrical system
Post by: Eyeketsarin on January 08, 2018, 09:52:59 AM
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