Wiring diagram review

[shymond]

Vito Diagram

I was hoping someone could do me a massive favour and look over my campervan schematic. I've been a bit confused about wire gauges and fuses. After consulting other schematics and the Victron manuals have come up with this. In general all cable runs are short as everything will be compact in cabinet, excluding the starter battery and Orion which is approx 2.5m from rest of the system, and Lithium battery is about 1.3m from Multiplus.

I have already bought most of the larger components.

• Multiplus 12/800/35
• Orion 12/12 - 30
• MPPT 100/30
• 2x Victron 175W solar panels
• Creabest Lithium 175AH
• Victron busbar 150A (for earth cables)

I'm not sure do I need Victron Battery Protect and Victron Smart Shunt?

I didn't want to buy all the smaller items (cables, fuses, busbars, etc.) until I had the entire diagram figured out for my campervan.
This is what I've come up with. I would highly appreciate any feedback of my setup before I start buying the rest.

Thank you in advance!

 

[St3v3]

Fuse box busbar is the wrong way around. Don't be tempted to use an MC4 inline fuse on the solar. They're rubbish! You probably don't need a fuse at all on there.... A fuse is to protect the cable, which is rated higher than the panel can produce.

 

[AdrianChen]

I don't use a battery protect in my system on the starter or leisure battery. I rely on the lithium's BMS to turn off, and the starter shouldn't get run flat other than from the alarm/tracker over time - would sooner have that running than protecting the battery from being unable to start up.

I have a Smart Shunt which is very useful for monitoring the battery. I didn't use a BMV since I have other displays and relays available. Once "dialled in" a shunt will likely give better accuracy than the built in BMS app of a lithium battery (I don't have a battery BT/App anyway ) and some other useful functionality.

If you can I would be tempted to go for the Victron Orion XS rather than the 30amp, just because the XS is more efficient and doesn't get hot, so wont drop output to 20-25amps. The XS and Solar controller will also take voltage data from a shunt, using a Smart Network over bluetooth and so compensate for any voltage drop to give very accurate charging voltage/profile. Depending on your battery low temp charging protection, (Some early batteries I know only shut off the battery at very low temps, but not charging below 5°c but I know nothing about Creabest). I would also consider a Victron temp sensor plugged into a shunt so the XS and Solar can be set not to charge below 5°c. (Standard Orion cant do that).

A couple of questions:-

What cable size are you using for the chassis earth cables?
Is the Multiplus to chassis earth busbar the case earth point rather than AC, being dim I don't understand the AC side earthing?
What is the cable run length from the solar controller to busbar? - Are you happy about the voltage drop from 6mm cable?

 

[autorouter]

I note there is no explicit chassis connection to the battery negative shown in the diagram. As you probably know, the starter battery negative will be connected to the chassis. The alternator (not on your diagram) negative terminal connects directly to the engine metal, and there is a thick braided flexible wire connecting the engine block to the chassis. This is intended to carry the negative return current from the starter battery to the alternator. So the starter battery negative is definitely connected to the chassis to allow charging from the alternator. It's the usual arrangement in all vehicles.

Because of this, the DC system negative is connected to the chassis. That means the 'earth' wire to the B2B is probably unnecessary since the common negative is earthed via the chassis.

Motor vehicles usually use the metal chassis as a negative return, it saves on the weight and expense of heavy wiring. But in a motorhome with wood, foam, fibreglass, thin aluminium etc. there is often no convenient metal for the return, so a pair of positive and negative wires is quite common.

Another thing, will those two mains boxes be located next to each other? If you are wiring sockets from both boxes, you should put a prominent notice to isolate both mains switches before working on any wiring. It's quite usual to do this on 'Dual supply' systems, something like this:

https://www.cef.co.uk/catalogue/products/4350289-warning-multiple-supply-label-pack-of-10

 

[autorouter]

I've been a bit confused about wire gauges and fuses. After consulting other schematics and the Victron manuals have come up with this.

If you know the cable length and the amps, you can calculate the voltage drop along the cable. The usual advice is to keep the total voltage drop to 3% or below. If you keep below 3% then the cable will also be well within the limits for safety. There are several voltage drop calculators online, including this one.

Voltage Drop Calculator | 12 Volt Planet

Use our Voltage Drop Calculator to select the correct Cable for your campervan, motorhome or boat wiring application. Auto and Marine Electrical Components from 12 Volt Planet - Cable Size Calculator

www.12voltplanet.co.uk

There's a few other relevant web pages on the 12VPlanet website too.

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[rod_vw]

I am watching comments on this with interest as I have a camper that has Victron kit installed but not by me (unusually). Maybe I will be making changes to mine in the light of various comments here and elsewhere.

I have one comment to make to the OP, if you have a vehicle with a smart alternator and then almost certainly a battery monitor module attached to the -ve pole of the engine battery you should NOT have any other connection direct to the -ve pole of the engine battery. If you do it confuses the smart alternator control system as it cannot monitor all of the current going out of the engine battery.
Regardless of the above the -ve connection for your leisure -ve busbar should, in my opinion, go to the nearest GOOD chassis ground. That should reduce the cable length (and potential volt drop) of that main -ve connection.

 

[shymond]

Fuse box busbar is the wrong way around. Don't be tempted to use an MC4 inline fuse on the solar. They're rubbish! You probably don't need a fuse at all on there.... A fuse is to protect the cable, which is rated higher than the panel can produce.

I been looking for them today. Thank You for advice.

 

[shymond]

I don't use a battery protect in my system on the starter or leisure battery. I rely on the lithium's BMS to turn off, and the starter shouldn't get run flat other than from the alarm/tracker over time - would sooner have that running than protecting the battery from being unable to start up.

I have a Smart Shunt which is very useful for monitoring the battery. I didn't use a BMV since I have other displays and relays available. Once "dialled in" a shunt will likely give better accuracy than the built in BMS app of a lithium battery (I don't have a battery BT/App anyway ) and some other useful functionality.

If you can I would be tempted to go for the Victron Orion XS rather than the 30amp, just because the XS is more efficient and doesn't get hot, so wont drop output to 20-25amps. The XS and Solar controller will also take voltage data from a shunt, using a Smart Network over bluetooth and so compensate for any voltage drop to give very accurate charging voltage/profile. Depending on your battery low temp charging protection, (Some early batteries I know only shut off the battery at very low temps, but not charging below 5°c but I know nothing about Creabest). I would also consider a Victron temp sensor plugged into a shunt so the XS and Solar can be set not to charge below 5°c. (Standard Orion cant do that).

A couple of questions:-

What cable size are you using for the chassis earth cables?
Is the Multiplus to chassis earth busbar the case earth point rather than AC, being dim I don't understand the AC side earthing?
What is the cable run length from the solar controller to busbar? - Are you happy about the voltage drop from 6mm cable?

1) For Earth cables I though about 16mm2.

2) After consulting other diagrams I get to that conclusion. However right now I think that AC should go to different point than DC

3) From MPPT to Busbar is about 0.4m so look like cable 6mm2 is absolutely enough.

 

[autorouter]

2) After consulting other diagrams I get to that conclusion. However right now I think that AC should go to different point than DC

The fundamental idea of a Protective Earth is that all exposed metal parts should be earthed. The metal chassis is definitely an exposed metal part, so it should be connected to earth. The fact that the chassis is also used as a negative DC return is irrelevant, there's no reason why it can't do that as well as being a protective earth. It's the usual arrangement in a motorhome.

 

[shymond]

The fundamental idea of a Protective Earth is that all exposed metal parts should be earthed. The metal chassis is definitely an exposed metal part, so it should be connected to earth. The fact that the chassis is also used as a negative DC return is irrelevant, there's no reason why it can't do that as well as being a protective earth. It's the usual arrangement in a motorhome.

So. As I understand that all earth cables can go to same point.
After checking all Victron manuals, wiring calculators etc. Look like my diagram is ok, right?
Only thing that Orion don't need any earth cable.
Appliances, I will work out in later stage as some of them not necessery need 2.5mm2 cable - ex. radio.
And right now I'm thinking to move electric cabinet to other side of the van, as that allow me for better ventilation and cooling. Unfortunatelly cable from battery to Multiplus will be a bit longer, around 0.3m (however still within Victron manual), but that reduce lenght of Orion cable from 2.4m to 0.5m.
Another positive negative or like I been thinking earth busbar to chassis reduce from around 1m to 0.4m
Once I will sort out diagram. I will upload.

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[shymond]

Updated diagram.
Could someone check that for me please.

 

[rod_vw]

If you mean by the annotation that protective earths are 16sq mm i.e. the yellow lines in your diagram I don't see any reason for them to be more than 2.5sq mm. After all that is what they would be in a domestic situation in a 13A ring main for instance.