Electrics Upgrade - Am I nearly there?

[8balladdict]

Hi all,

So my AGM leisure battery died last week, but it was 8 years old so it had a good life. I'm going to replace it with a lithium battery and so begins another upgrade project on the van.

My current setup comprises of CTEK D250A DC-DC charger, Victron 75/15 MTTP, 130w solar panel and a Victron BMV-712 shunt. So I know I need to replace the CTEK as that doesn't support Lithium.

As part of the upgrade to a 230Ah Fogstar Drift SB lithium battery, I'm going to replace the CTEK with a Victron XS 50A DC-DC, replace the BMV-712 with the Smart Shunt, add 230v hookup, an inverter (yet to be decided on make/model), a Victron IP22 mains battery charger and a Sterling 3A B2B charger.

I need to put a shopping list together as I'm aware there's lots of bits and pieces needed to connect it all up correctly and more importantly, safely. This is where I need some guidance as to if I'm on the right track. I've put together a wiring diagram of how I 'think' it needs to be put together, including what fuses I believe are the right ratings for the kit I'm planning on installing. The only thing I've not worked out yet is length and gauge of wiring, but I can do that after I know the ratings I'm looking at are right and once I've checked the currently installed wiring and run lengths for the new kit. So here it is.....



So in terms of the fuses, am I good to go or am I missing something fundamental or doing something overkill?

My solar currently doesn't have a way to isolate it, or inline fuses from what I can tell, so I plan to add a 20A inline breaker before the MTTP and a 20A midi fuse between that and the positive busbar.

My understanding is that anything I can't connect to the negative busbar can just be grounded to the chassis, is this so? The IP22 will be at the back of the van so can I ground that to the chassis or do I need to run that back to the battery/negative busbar?

As for the 230v part, I've done some research that suggests that the RCD shouldn't/doesn't need to be earthed to the van, given that any campsite or mains power supply is generally always going to have it's own protection, so just having the RCD protection is all that's needed. Might be a contentious topic. My understanding is also that DC and AC systems shouldn't be earthed to the same thing, so if that's the case, how can you separate those on a vehicle anyway?

Apologies if I'm chatting any gibberish - I've been doing hours and hours of research over the last week and keep going down all kinds of rabbit holes and confusing myself.

Any help, pointer or advice welcome!

 

[ginkster]

Looking good. I’ve not looked in massive detail but generally looks fine. A few thoughts:

Avoid those breakers as they are rubbish (unless genuine Blue Sea ones). Use a fuse and/or switch instead.

No need for the fuse at the Orion end of the cable from SB as no current going from Orion to SB.

I’d recommend the Ablemail AMT12-2 to trickle charge the SB instead of the Sterling. It’s tiny, simple to fit, good value and works brilliantly.

Why are you replacing the BMV-712? It’s essentially the smart shunt with a display. Or is there an old version without Bluetooth?

Have you considered the IP65 instead of the IP22? Totally silent and can be fitted so it can be removed and used elsewhere if needed.

You don’t need a fuse for a single solar panel. An isolator is a good idea for maintenance and managing charging. I used a double pole isolator and enclosure.

Grounding to the chassis is good. Just make sure it is a good contact. Ideally use the original ground points (one under each seat and one in each rear corner). There is a plan of these in the VIP area.

Use a quality 275a isolator rather than a copy off Amazon/ebay. Victron or Blue Sea are good.

The diagram below will help you with cable sizing. Aim for the <3% voltage drop.

 

[TallPaul_S]

@ginkster has covered most of what I would have said, for the positive busbar maybe use one of these midi/mega fused busbars rather than separate fuses, should make things much tidier.

MEGA - MIDI fuse distribution box

MEGA - MIDI fuse distribution box - Professional quality automotive MEGA-MIDI fuse distribution boxFittings are 2 x M8 studs & 4 x M5 studs with attached nuts.

www.simplysplitcharge.co.uk

For fusing, remember the aim is to protect the cable runs from the source of highest power, in this case that's the battery. So if there was a short in any cable coming from your positive busbar, the fuse on the battery end would pop before battery could send hundreds of amps via the short circuit.

I have a very similar set up to your planned set up:

230Ah fogstar seat base
Victron Orion XS 50a
Victron 100/20 MPPT
305w solar panel
Victron smart shunt
Ablemail AMT12-2
Renogy 2000w inverter




Plus a Cerbo GX and touch 50



You'll need 16mm² for the cables into the Orion 50a (+ heat shrink for the strain relief cover)
I've gone with a 300a main fuse, and 250a Megafuse in that fused busbar, for my 2000w inverter, with 50mm² cable for the main runs from the battery and fuse (mounted directly on the positive terminal) to the fused busbar, and negative runs from the battery/shunt to the negative busbar, and the same 50mm² for the inverter cables.

 

[8balladdict]

Thanks @ginkster and @TallPaul_S. It’s reassuring to know I’m on the right track.

In response to @ginkster, thanks for the heads up on the breakers, will look at alternative options.

I had looked at the AMT12-2 but given the price for it is basically the same as the Sterling, I figured I’d just go with that. Plus the fact it was IP65 so I can mount it in the engine bay next to the SB. I’m looking at doing a similar install to @TallPaul_S so space under the seat is going to be very limited.

As for the Victron, the 712 I have does have Bluetooth but it’s via the display screen module thing which is currently just coiled up under the seat. So it’s purely just to save space, plus a friend of mine is going to have the 712 once I’ve got it out.

I did look at the other Victron chargers but I’ve already got a portable CTEK charger so will just perm install the IP22 for the higher charge rate.

Thanks both for the info on the fuses and cable sizing, will definitely look at the Victron isolator plus the fused busbar as that does seem like a better solution. As soon as I’m locked in on the cable size v length, I’ll make sure the fuses are appropriate.

 

[roadtripper]

I'd agree with the comments so far.

With charge rate I'd keep the Orion XS around 30A for general use, it's kinder on the battery, charger and keeps the heat down. You can always bump it up to the full 50A for a the week or two you're off grid and really drawing on the battery.

With the trickle chargers keep in mind a lot of folks use the AMT-12 so there is a reasonable depth of forum knowledge on tweaking the setup (if needed) whereas I can't remember when I last saw someone mention the Sterling unit.

As for the 230v part, I've done some research that suggests that the RCD shouldn't/doesn't need to be earthed to the van, given that any campsite or mains power supply is generally always going to have it's own protection, so just having the RCD protection is all that's needed. Might be a contentious topic. My understanding is also that DC and AC systems shouldn't be earthed to the same thing, so if that's the case, how can you separate those on a vehicle anyway?

You need the van body grounded to the incoming protective earth. If not any fault that connected the line conductor to the van body would not trip anything as the wheels are a good insulator - the first thing to allow the fault current to go to ground is likely to be someone touching the van while standing on the ground and then they become the ground conductor...

The RCD at the EHU post is there to protect people from faults in the cable to your van, the one in the van is to protect the faults in the van.

Nothing magical about DC and AC, they can both share the same ground reference, a great many devices in your home already so (which is why you now need to fit RCDs that work with DC faults as well just in case). There are cases in the marine industry where grounding a metal hull needs to be done with care to ensure galvanic corrosion doesn't occur, but that's not generally a risk in a road vehicle.

 

[8balladdict]

for the positive busbar maybe use one of these midi/mega fused busbars rather than separate fuses, should make things much tidier.

@TallPaul_S - Been looking in to these today, look like a good solution. Quick question though, looks like I'll need 6 positive feeds coming out from the battery and the distributor you linked can only handle 4....what would I do with the other 2?

Two other questions if you don't mind - where have you installed your AMT12-2 and what have you done with your solar? Do you have an isolator and where have you managed to squeeze that? I saw your install on some of the other threads and thats where I got the idea to follow suit and go with the 230Ah battery rather than a smaller one.

My biggest issue is that I don't really have any cupboards to hide any of this stuff in and my passenger seat is filled with an subwoofer so can't use any of that space.

Nothing magical about DC and AC, they can both share the same ground reference, a great many devices in your home already so (which is why you now need to fit RCDs that work with DC faults as well just in case)

@roadtripper Thanks for the message and info. I'm just about getting my head around the DC lecky stuff and chucking AC in is tipping me over the edge! So what I heard, was that having AC and DC grounded to the same reference can cause interference with the CAN Bus and other electrics.

So what you are advising then, is that the RCD should be grounded to the chassis so that it's then connected to the incoming earth from the mains? Sorry if I'm missing the point here!

I will have another look at the AMT12-2, cheers for the pointer.

 

[ginkster]

@TallPaul_S - Been looking in to these today, look like a good solution. Quick question though, looks like I'll need 6 positive feeds coming out from the battery and the distributor you linked can only handle 4....what would I do with the other 2?

I used one of these too and meant to mention it in my earlier post. You get 5 output fuses with that as the LB is already fused and comes in at one end of the mega fuse and across the busbar. I’d then suggest using the mega for the inverter. The 4 midis can then do fuse box, MPPT, IP22 and DC-DC. Anything else could be fused independently and taken off the LB isolator (connected to same bolt as cable to busbar).

The AMT is tiny (smaller than a pack of playing cards) and can easily tuck into the cavity formed by the sloping sides of the seat base (it can be stuck on). It just needs 3 small (1.5-2mm2) cables - one to DC-DC input, one to DC-DC output and one to ground. You can see mine in top left of seat base pic below:

 

[8balladdict]

I used one of these too and meant to mention it in my earlier post. You get 5 output fuses with that as the LB is already fused and comes in at one end of the mega fuse and across the busbar. I’d then suggest using the mega for the inverter. The 4 midis can then do fuse box, MPPT, IP22 and DC-DC. Anything else could be fused independently and taken off the LB isolator (connected to same bolt as cable to busbar).

The AMT is tiny (smaller than a pack of playing cards) and can easily tuck into the cavity formed by the sloping sides of the seat base (it can be stuck on). It just needs 3 small (1.5-2mm2) cables - one to DC-DC input, one to DC-DC output and one to ground. You can see mine in top left of seat base pic below:

View attachment 259269

Ok, that’s me sold on both of them then!! Didn’t realise the charger was so small. Awesome. Do the cables to and from the AMT need fuses?

 

[Skyliner33]

Ok, that’s me sold on both of them then!! Didn’t realise the charger was so small. Awesome. Do the cables to and from the AMT need fuses?

The 2 positives should be fused. It only uses 3A so small inline fuses can be used. Fused up protect the wire as always.

 

[8balladdict]

The 2 positives should be fused. It only uses 3A so small inline fuses can be used. Fused up protect the wire as always.

Ok cool, guessed as much. Cheers. AMT12-2 has been ordered

 

[roadtripper]

For mobile wiring I'd always recommend a good read of the very good Victron Wiring Unlimited:

7. Ground, earth and electrical safety

www.victronenergy.com

It's not Victron specific and it distills good AC and DC wiring practice while explaining why it's important.

In your case it's not "grounding the RCD" but two separate things:

• Grounding your installation (van body) so that faults will not make metal live relative to the ground and will.give the fault current somewhere to flow
• Installing an RCD so that if fault currents flow power will be switched off

As for canbus interference from AC due to shared ground, theoretically yes, but only if you have AC devices with horrible EMI and no filtering. Even then if you had those they would radiate enough energy to induce currents, doesn't need a connection. In normal operation there will be nothing flowing in the AC protective earth anyway, it's not like you are using the van body as the Neutral side of the circuit.

And at the end of the day canbus is an industrial safety critical protocol that's used to operating in electrically harsh environments - the high voltages involved with petrol engine ignition systems all share a common ground with no issues.

Just use decent quality kit rather than chinesium off brand and you'll have no issues - pay attention to any switch mode power supply (anything that's converting voltages like a laptop power supply or battery charger)

 

[8balladdict]

For mobile wiring I'd always recommend a good read of the very good Victron Wiring Unlimited:

7. Ground, earth and electrical safety

www.victronenergy.com

It's not Victron specific and it distills good AC and DC wiring practice while explaining why it's important.

In your case it's not "grounding the RCD" but two separate things:

• Grounding your installation (van body) so that faults will not make metal live relative to the ground and will.give the fault current somewhere to flow
• Installing an RCD so that if fault currents flow power will be switched off

As for canbus interference from AC due to shared ground, theoretically yes, but only if you have AC devices with horrible EMI and no filtering. Even then if you had those they would radiate enough energy to induce currents, doesn't need a connection. In normal operation there will be nothing flowing in the AC protective earth anyway, it's not like you are using the van body as the Neutral side of the circuit.

And at the end of the day canbus is an industrial safety critical protocol that's used to operating in electrically harsh environments - the high voltages involved with petrol engine ignition systems all share a common ground with no issues.

Just use decent quality kit rather than chinesium off brand and you'll have no issues - pay attention to any switch mode power supply (anything that's converting voltages like a laptop power supply or battery charger)

Thanks for the info, will defo have a read of the guide you sent and also take on board what you’ve said. Updated diagram incoming…..

 

[8balladdict]

Thanks for all your help @ginkster, @TallPaul_S, @roadtripper - its been invaluable and greatly appreciated.

So I've taken on board everyone's comments and suggestions and come up with the following, hopefully final, draft diagram.

To summarise the changes:

Added a 300A MRBF terminal fuse
Added a 300A isolator
Added a Mega/Midi Fused Distribution box which will include the following:

250A Mega fuse for the inverter​

60A Midi fuse for the Orion XS​

40A Midi fuse for the 30A IP22​

40A Midi fuse for the Blade Fuse Holder/12v Appliances​

30A for the MPPT 75|15​

Swapped the Sterling for an AMT12-2 and wired appropriately
Added an PV 2-pole isolator
Added an earth from the RCD

I plan on using 50mm² for the main leisure battery terminals and for the inverter cables and then 16mm² for everything else bar the AMT12-2, solar and 230v stuff. I've added a highlighted list to the diagram to show this in more detail.

How's that looking now? Hopefully thats everything covered.....?

 

[TallPaul_S]

That looks scarily similar to my set up, right down to the 300a terminal fuse

Is this all going under one of the front seats? If so the fuse won't fit on the Fogstar terminal directly, I made a short copper busbar to allow it to fit upside down. If you're not fitting yours under a seat then you won't need to worry about that.

Make sure you've got a decent set of crimpers for the 50mm² cable, it's hefty stuff!

 

[z1ts]

final, draft

Sounds like my plans for life in general!!!

 

[roadtripper]

Crimping anything over around 30A cable is serious engineering as you have to crimp it hard enough for the copper to form one solid lump otherwise corrosion can get in and make the inner cores resistors.

Worth trying to see if a local motor factor will crimp them up or see if a fellow forum member already has the tools and might help out for a few beers.

 

[8balladdict]

That looks scarily similar to my set up, right down to the 300a terminal fuse

You could have just me a wiring the wiring diagram then, I’ve spent hours knocking that up

Is this all going under one of the front seats

Yeah, the drivers seat. And it has a swivel on it. I was assuming it would have to go upside down but ok, more consideration needed then. Would you mind giving me more info on how you made the copper busbar thing?

As for the crimping, I was going to look at getting pre-crimped cables made up from 12vP but maybe that’s not going to be bespoke enough for this install, especially with the inverter being about 1.5-2m from the battery. Thanks for the warning about this @roadtripper. I’ll look at the options.

Other than that, I guess I’m pretty much there then

 

[The Flying Scotsman]

I bought this set to do my cables.
I also ordered some 50mm crimps and larger heat shrink.

https://amzn.eu/d/2351EhY

 

[TallPaul_S]

You could have just me a wiring the wiring diagram then, I’ve spent hours knocking that up


Yeah, the drivers seat. And it has a swivel on it. I was assuming it would have to go upside down but ok, more consideration needed then. Would you mind giving me more info on how you made the copper busbar thing?

As for the crimping, I was going to look at getting pre-crimped cables made up from 12vP but maybe that’s not going to be bespoke enough for this install, especially with the inverter being about 1.5-2m from the battery. Thanks for the warning about this @roadtripper. I’ll look at the options.

Other than that, I guess I’m pretty much there then

Details here (and for all my electrics actually) in my build thread - TallPaul's Caravelle - MTB wagon!

I used this copper bar, cut and drilled.


I've got the factory passenger swivel and so long as you cut out the factory ground stud it'll find just fine.

 

[8balladdict]

I bought this set to do my cables.
I also ordered some 50mm crimps and larger heat shrink.

https://amzn.eu/d/2351EhY

Cheers for the link pal