Upgrading the Factory Electrical Design

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lumpycrumpet asked Mar 18, '24

Upgrading the Factory Electrical Design

I have a VW Crafter 35 Panel Van. It has a factory Varta 100A starter battery (under the passenger cab floor) which is connected to several factory 12vdc internal lights and factory 12vdc sockets. All running on the factory 12vdc bus bar/fuse box. This model crafter has a factory option to add a second battery (in the engine bay), and also add a second alternator (factory starter alternator is Bosch 180A NOT Smart) which could be another 12vdc or perhaps a 48vdc separated from the factory 12vdc circuit for AC inverter consumption.

I'm wanting to add that second 12vdc battery to help my starter battery with the camping load on those lights and 12vdc sockets, one of which supports my 40L Engel fridge. Adding a second battery the factory way would integrate the second battery into the starter battery circuit.

My concerns are

Should I add the second battery to the starter battery circuit or keep the second battery separate from the starter battery circuit. In other words install a separate bus bar/fuse box to support those internal lights and 12vdc sockets?
The quality of the factory circuit elements (isolator, etc) when adding a second battery to the starter battery circuit. Can I do a better job adding some Victron parts instead, and what should they be, based on value for money criteria? I'm thinking a Wakespeed here might be a tad overkill.

Later, I plan to add the second alternator to support the 240vac circuit for kitchen appliances and maybe an air conditioner. I have diesel powered stove top (Wallas) and furnace (Eberspaecher) for hot air heating and hot water.

My concerns are

How do I get all that alternator power to support both 12vdc and 240vac circuits?
How do I get the future solar and inverter charger to support both 12vdc and 240vac circuits?

I'm trying to design the system to support the above and build it incrementally as funds allow. I'd appreciate any ideas to draw a complete electrical diagram before implementing the design.

Cheers

system design

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Answer 1 · 2024-03-18T12:30:09Z

max-payne answered · Mar 18 at 12:30 PM

I dont see why you cant add a battery in parallel to your existing 12V battery. It will behave like a bigger battery.

Do the least amount of changes needed since every change is a possible source for mistakes. I would not replace factory VW parts with Victron parts.

If you want a grid inside your caravan with solar panels there is lots of tutorials out there but the simplest solution would be to add these components via 2 options:

Quality System:
48V Battery system
Cerno GX
Multiplus-II 3000
RS Solar

Cheap System:

12V lead acid
Victron sun-inverter

Both pretty much make a grid for you. One with 3000W the other one with 250W. Both support Solar. You dont need an alternator that supports ac and dc. Just the battery and from there the victron system is responsible for SOC and the grid.

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Answer 2 · 2024-03-19T03:12:44Z

lumpycrumpet answered · Mar 19 at 03:12 AM

Thanks for your comments @Max Payne. Yes, the VW factory installs the second 12vdc battery in parallel with the starter battery using VW electrical components.

My question is: Can I improve that basic expensive VW system by using better quality Victron components? My system design principles are -

Maximise the Bosch 180vdc non-smart alternator charge capability

Protect the starter battery so the vehicle will always start

Quickly charge the second battery to reduce engine running time

A scalable electrical system to easily integrate with the 48vdc system (charging can be shared)

Another question is: I notice the starter battery is directly connected to the starter/alternator. Is this because the design principles of the VW electrical system is just to keep the starter battery charged? When the focus changes to house batteries, I see lots of discussions about external regulators and the benefits they bring, such as

Battery life is increased (3 phase charging, temperature monitoring), and

Alternator control preventing burn outs (charge control and temperature monitoring)

Perhaps directly charging or using an external regulator instead, is more about value for money considering the external regulator is costly?

I'd appreciate any insightful comments, I welcome all your comments

Thank you

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Answer 3 · 2024-03-19T03:42:29Z

JohnC answered · Mar 19 at 03:42 AM

@LumpyCrumpet

The 'Victron Van' project was on a VW. Maybe not the same model as yours, but you might glean some useful info on how you could approach it.. https://www.victronenergy.com/blog/2019/06/18/the-victron-van-install/

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Answer 4 · 2024-03-19T03:54:42Z

lumpycrumpet answered · Mar 19 at 03:54 AM

Thanks @JohnC I've just opened the link and it all looks interesting, I'm sure I'll find something of value, thank you. I think their van is a Transporter, a smaller version of my Crafter, but that should make no significant difference.

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Answer 5 · 2024-03-19T05:24:02Z

kevgermany answered · Mar 19 at 05:24 AM

All manuals for Victron products can be downloaded from the product pages at victronenergy.com

Based on my build:

Keep as simple as possible
Keep as safe as possible
Add second battery, but not in parallel, but do ground it to chassis
Leave VW wiring alone. Treat all house loads as separate system and don't drive house DC loads from starter battery.
Don't use high voltage DC parts like the RS series.
Don't run solar from AC. Use DC MPPTs .
Run 240V AC off a multiplus inverter charger.
Think now about future 240V loads and decide on house battery voltage. Running 3kW off a 12V battery is about 250A. 24V house battery drops this to 125A, going to 48V house means you're just over 60A. Big implications for cable sizes, ease of installation.
If house battery not 12V, use Orion converter for 12V loads. Output from this directly into fuse box.
Use Orion DC:DC charger to charge house from alternator. You can fit more than 1 in parallel.
Fit DC:DC trickle charger or low power Orion charger to maintain starter battery from house battery charging.
Ensure you comply with local regulations, especially for 240V.
Consider a GX device to control charging from shore and solar. Most of the Orions cannot be controlled by this, but the new 50A will gain it later. This can also add Geo location (with a GPS aerial), remote monitoring and tracking (needs internet) and easier management. The built in GX of some models of multiplus is functional, but basic.

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