System diagram check for truck camper

[HRTKD]

I'm pretty sure that in my RV the shore power ground is connected to the chassis. There shouldn't be any neutral-ground bond within the RV, except for when the inverter does it.

I'm not that familiar with how things work on the AC side, so don't take my word for it.

 

[filippomasoni]

Unless your inverter is neutral to earth bonded any RCD, RCCD, won't operate

If the inverter doesn't have a neutral-ground bond it can be made just after the inverter, like Meanwell specified to me and like I've seen described on a dometic inverter manual as well.
I do need to have an RCD because of Italy regulations, only exception is if using the existing plugs on the inverter or a power station. So that's a must for me.

 

[mikefitz]

Do I need to ground the shore power to chassis?

Yes, a requirement in the UK and I guess in Italy. Should you be connected to shore power and have a fault that makes vehicle metal 'hot', anyone touching the vehicle metal standing on (wet) ground would receive a shock, hopefully this will be limited by a RCD. ( note in the UK its been reported that when testing instalations 10% of RCDs fail the test).
Any metal housing of appliances, water system metal pipe/ tanks and any LPG (propane) metal pipe/appliance needs a bond to the vehicle metalwork
It's possible the RCD/RCBO you have won't function unless you have incoming PE connected to vehicle metal.
When always from shore power its the vehicle metal that's your 'ground'.

 

[HRTKD]

Should you be connected to shore power and have a fault that makes vehicle metal 'hot', anyone touching the vehicle metal standing on (wet) ground would receive a shock

This issue is not uncommon in U.S. RV forums. Half the time it's the fault of the factory I suspect. The other half it's a DIY screw up.

 

[filippomasoni]

Got it, than it looks like my previous diagram is correct, with shore power ground connected to the negative busbar, which is then connected to chassis. I've updated it, see below, to have an AC combiner box with everything AC inside including AC grounds, which will make it cleaner in the install and really close to inverter, charger and ac inlet.

In my current plan I don't have any metal appliances and the only AC one that require ground connection is the induction cooktop. The camper is composite, therefore the only connection to metal is the negative to chassis wire. The internal cabinet structure is made of extruded aluminum and I'll be mounting some electrical components there, but if I have everything grounded like te diagram it shouldn't be an issue.




I've also updated the PV breaker as I've found Airpax DC breaker available in 2 poles as well at reasonable prices, 15-20 euro. They are rated at 80VDC so should be enough for my solar, they won't work for a series connection, but even the mppt won't work in series.

If you can't find any other issues I'll start ordering parts and installing it soon.

Thanks for the help

 

[Drizzt321]

For going from the MPPT -> bus-bars, you have a notation of double wiring? 2 sets of 6mm2 wiring? Why that, instead of a single slightly larger wire? Although for 30a (you'll max out the MPPT controller with both panels at maximum production) output, you 6mm2 might be a bit undersized, but surely 8-10mm2 should be sufficient? Get some welding wire, that's ultra flexible, should manage turns/bends fine. Or am I missing something?

For the Orion XS 12-24, have they said what the max output will be? On that 6mm2 you might want to limit the output power to ~20-25a, even with that short of a run. If it'll do up to 50a like the 12-12 version that's out now, you'd want to go larger if you want to run it at the peak.

Isn't the pre-charge circuit usually done at the inverter? Although certainly no reason why it can't be at the main battery after the fuse as you have it.

Hm. Does the inverter need to be "on" when the DC is connected in order to charge the capacitor? Or can you turn the inverter on and off at will, once the capacitors have been charged after connecting to the DC side? I need to research that some more I think, for myself.

For the inverter wiring, interesting, the manual (I think this is the right one https://www.meanwell.com/Upload/PDF/NTS,NTU-E.pdf) has 100-125a as 35mm2, which is what you note, but according to https://www.rapidtables.com/calc/wire/awg-to-mm.html that's 35mm2 is slightly larger than 2awg, yet it calls for 1awg/35mm2 in the manual. Probably fine I'd say, just an odd discrepancy of calculation between sources.

Looking good though!

 

[filippomasoni]

@Drizzt321 thank for catching the mistake. I've updated the diagram. I left the 2 set of 6mm2 from the 2 100/20 I had previously, now that I've got a single 100/30 like they suggested I'll have a single wire run of 10mm. Although the 6mm2 FLRY-B that I'll be using (available through a seller for automotive, marine flexible wires) is rated at 53A https://www.elandcables.com/media/39716/flry-b-cables.pdf
These FLRY-B should be flexible enough and are available up to 25mm2 while the other H01N2-D which should be welding wire goes from 10-95mm2 so I'll use a combination of the two based on availability.

you'll max out the MPPT controller with both panels at maximum production

Yes, from victron MPPT calculator I'll actually be limited both at low and max temp with a PV ratio of 102%.
I also updated the panels to the 450W instead of 440W since now that's the version available, which is better, but I can't get max output with a 100/30 having them in parallel.
My understanding is being flat on the roof of a camper they will never get 100% of the rating just because of the angle, unless when I'll go to the tropics so I won't loose any production, but please let me know if I'm missing something.
My original plan was to get 2x 100/20, one for each panel, but since a 100/30 is the same weight, slightly smaller, less wires, less breaker and cheaper, I decided to follow the first suggestions I got here and put the panels in parallel. I'm not sure what advantage I'll get to put panels in series and go with a much more expensive 150/35, other than having less performance in case of partial shading.

For the Orion XS 12-24, have they said what the max output will be?

It just popped up on a few sellers and they updated the manual and data sheet https://www.victronenergy.com/upload/documents/Datasheet-Orion-XS-DC-DC-battery-charger-EN-.pdf I'm still not sure, but from reading I understand it's 50A max input and output, so if I connect to a 12V battery it will max out on the input at 50A so I'll get 25A output, still a better than the old 12-24 15A. The 6mm2 wire rated at 53A is probably fine, but I can go with a 10mm no problem, such a short run.

Isn't the pre-charge circuit usually done at the inverter?

Yes, but when testing the battery the first time, I actually had some sparks just plugging the bench power supply (probably has some capacitors), so I thought I might as well put the precharge switch as the main, it won't hurt.

Does the inverter need to be "on" when the DC is connected in order to charge the capacitor?

The inverter has the option for a remote on-of switch as explained in the manual you shared, but it won't disconnect the inverter, so the capacitors will stay charged. The same way they instantly charge when you connect them if the inverter is off. That's my understanding but I'm not sure. I don't think everyone that has a precharge switch is turning that on and off to turn the inverter on-off.
In the event I need to physically disconnect it, (probably a few times during the install) I'll switch the entire battery off so I don't have to worry about accidental shorts when doing stuff.

or the inverter wiring, interesting, the manual (I think this is the right one https://www.meanwell.com/Upload/PDF/NTS,NTU-E.pdf) has 100-125a as 35mm2, which is what you note, but according to https://www.rapidtables.com/calc/wire/awg-to-mm.html that's 35mm2 is slightly larger than 2awg, yet it calls for 1awg/35mm2 in the manual. Probably fine I'd say, just an odd discrepancy of calculation between sources.

Didn't even see that discrepancy to be hones. I based my wire calculation using this app: https://play.google.com/store/apps/details?id=it.Ettore.calcolielettrici&hl=en it's pretty well made and has all the IEC, NEC codes, considers many methods of installation, probably even overkill, but I based on that and the rated ampacity of the types of cable I'm using. For example for 150A at 24V open air install with PVC insulation (my wires are rated at 85°c instead of the usual 70) gives me 35mm2 that has an ampacity of 162A, since I have a 150A fuse it should be fine. H01N2-D welding cables spec sheets quote 180A continuous rating for a 35mm2.

 

[Drizzt321]

My understanding is being flat on the roof of a camper they will never get 100% of the rating just because of the angle, unless when I'll go to the tropics so I won't loose any production, but please let me know if I'm missing something.

Most likely correct, flat on the roof most likely you won't be close enough to max output to hit the limit, while at the same time the bigger panels will give you better production for being flat, or when it's a cloudy day.

It just popped up on a few sellers and they updated the manual and data sheet https://www.victronenergy.com/upload/documents/Datasheet-Orion-XS-DC-DC-battery-charger-EN-.pdf I'm still not sure, but from reading I understand it's 50A max input and output, so if I connect to a 12V battery it will max out on the input at 50A so I'll get 25A output, still a better than the old 12-24 15A. The 6mm2 wire rated at 53A is probably fine, but I can go with a 10mm no problem, such a short run.

Ah, gotcha. Just want to make sure you have big cables on the input then. Don't forget that they'll at least partially sit in the engine compartment, so that'd be a good amount of heat, so 50a on a 53a rated cable is really too close to the theoretical limit, unless the cable is being kept on the cool side. I tend to go with the 80% rated capacity, if it's enclosed or will be in a hot area derate even more.

The inverter has the option for a remote on-of switch as explained in the manual you shared, but it won't disconnect the inverter, so the capacitors will stay charged. The same way they instantly charge when you connect them if the inverter is off. That's my understanding but I'm not sure. I don't think everyone that has a precharge switch is turning that on and off to turn the inverter on-off.

Ah, gotcha. Was somewhat my thinking as well, that the DC capacitors charge regardless of the inverter on/off state.

Didn't even see that discrepancy to be hones. I based my wire calculation using this app: https://play.google.com/store/apps/details?id=it.Ettore.calcolielettrici&hl=en it's pretty well made and has all the IEC, NEC codes, considers many methods of installation, probably even overkill, but I based on that and the rated ampacity of the types of cable I'm using. For example for 150A at 24V open air install with PVC insulation (my wires are rated at 85°c instead of the usual 70) gives me 35mm2 that has an ampacity of 162A, since I have a 150A fuse it should be fine. H01N2-D welding cables spec sheets quote 180A continuous rating for a 35mm2.

But are you installing in open air? Or at least a well ventilated (with fan or what not) case? Probably fine, but as I said, I tend to go for 80% of rated capacity derating. Just because the sheathing is rated for the heat, doesn't mean what's around it or touching the cable (cable ties, etc) is rated for that temp.

 

[filippomasoni]

Don't forget that they'll at least partially sit in the engine compartment, so that'd be a good amount of heat

I did consider that, the FLRY-B 25mm2 is rated at 132A, so that would be plenty. It's rated for 105°C and I'll place it inside a conduit to avoid contact, scratches etc, but it will experience heat only for the initial part, than it will mostly be under the vehicle.

The issue is Victron DC-DC all have small terminals and accept up to 16mm2 or 4AWG( which would be better), according to their manual: https://www.victronenergy.com/media...tml#UUID-a7bceec9-bd1b-39a9-ddb3-7b8dee068639
They even say for <5m to use 16mm2 / 6AWG (13.3mm2), the FLRY-B wire is rated at 96A so that's fine, but voltage drop with 50A at 15V for a 4m run will be a 3.86% and end up with 14.4V which I think is bad, especially considering victron uses a voltage algorithm to turn on and off smart inverters, maybe the voltage drop is considered in the calculations.
I'm sure a 25mm2 is better but if it won't fit in the terminals, I'll have to strip a bit of strands before putting the ferrule.

But are you installing in open air? Or at least a well ventilated

The inverter wire run is so small from the busbar that I probably won't have it inside conduit like most other wires as it's anyway closed inside a cabinet, so open air and I will have vents in the bottom to draw fresh air and a fan out the side of the camper blowing hot air out when necessary. Everything will be controlled by home assistant, so I'll probably set up the fan to turn on automatically when the shelly measuring AC consumption will sense more than 1000W or when temperature reaches a certain amount.
But again such a short run, I could just use the same 50mm2 as I did from the battery and never think about it again.

Just because the sheathing is rated for the heat, doesn't mean what's around it or touching the cable (cable ties, etc) is rated for that temp.

I've never though about that, makes sense.

 

[Drizzt321]

The issue is Victron DC-DC all have small terminals and accept up to 16mm2 or 4AWG( which would be better), according to their manual: https://www.victronenergy.com/media...tml#UUID-a7bceec9-bd1b-39a9-ddb3-7b8dee068639
They even say for <5m to use 16mm2 / 6AWG (13.3mm2), the FLRY-B wire is rated at 96A so that's fine, but voltage drop with 50A at 15V for a 4m run will be a 3.86% and end up with 14.4V which I think is bad, especially considering victron uses a voltage algorithm to turn on and off smart inverters, maybe the voltage drop is considered in the calculations.
I'm sure a 25mm2 is better but if it won't fit in the terminals, I'll have to strip a bit of strands before putting the ferrule.

Definitely second using ferrules for those screw down terminals.

Hm, actually, that 50a is only when it's pulling max to charge, which means the battery is probably below 80-90% of charge. As it gets closer to full, it reduces current, which will help reduce voltage drop. So I think you'll be fine in terms of in->out voltage, especially since it's boosting, so voltage in doesn't have to be above voltage out.

So yeah, next time I need to just run the voltage drop calculator, it'll be fine.

It's rated for 105°C and I'll place it inside a conduit to avoid contact, scratches etc, but it will experience heat only for the initial part, than it will mostly be under the vehicle.

Yeah, make sure the conduit is rated for the high temp, at least near the engine compartment. And probably isn't metal, near that area, so it won't conduct heat and thus heat up the insulation & conductor. Maybe some kind of high temp nylon/teflon tube for 1/4-1/2 meter, and then transition to PVC or whatever else makes sense. Or just use that the whole way. Dunno, I never thought about it before now, or done any research. Maybe someone else here will reply with better thought.

 

[filippomasoni]

Yeah, make sure the conduit is rated for the high temp

I'll be using automotive corrugated PA tube, not sure the correct name in English, it's rated at 120C I believe. Same stuff that's already covering all the wires in the engine compartment. It's really light and cheap as it's what's used in most of the residential conduits buried in concrete or inside walls at least here in Italy. I'll be using it in the interior as well for some longer runs where it's not going to be seen.

 

[Backyard]

I'll be using automotive corrugated PA tube, not sure the correct name in English, it's rated at 120C I believe. Same stuff that's already covering all the wires in the engine compartment. It's really light and cheap as it's what's used in most of the residential conduits buried in concrete or inside walls at least here in Italy. I'll be using it in the interior as well for some longer runs where it's not going to be seen.

Maybe you're thinking of "wire loom"

 

[filippomasoni]

Maybe you're thinking of "wire loom"

Yeah I guess that's the correct name

 

[Drizzt321]

Didn't realize there was some rated to 120C, nice.