Re-engineering the Grand California 680 – from OEM compromise to a coherent, integrated system

[Bizzaru]

Hi everyone,

 

This story started in August 2024, when I bought a VW Grand California 680. During the first months (summer / early autumn) I enjoyed the van exactly as it came from the factory. Pretty quickly, however, the real limitations of the OEM setup became obvious.

Why I decided to take it apart completely

– OEM battery: real off-grid autonomy of 24 hours, after which the fridge went into protection
– weak shower pressure once the battery dropped
– toilet emptying: inconvenient and unpleasant chemical smell
– winter use: significant temperature difference between front and rear
– road noise: furniture and fittings → about 40% of driving fatigue

In short: it worked, but not as a coherent system.

 

Concept & approach

The decision was to rebuild the van as a system, not as a list of accessories.

Advantages:

• own workshop hall
• direct access to CNC machining, 3D printing and custom furniture
• 2–3 professionals involved throughout the project (electrical, mechanical, furniture)

The van was fully stripped: from the toilet area to the rear doors.
On one side, only the kitchen unit remained.

 

Insulation & structure

The OEM insulation was honestly very poor.
There were areas with no insulation at all.

I rebuilt the insulation completely:

• walls
• doors
• cold zones in the rear

The temperature difference between front and rear is now almost gone.

 

Electrical system – EcoFlow Power Kit

 

– EcoFlow Power Kit 5 kVA
– 3 batteries (one optional battery in the former gas compartment)
– battery placement designed to balance vehicle weight relative to the fresh-water tank
– dedicated fresh-air intake for EcoFlow (not recirculated warm air)

Current charging:

OEM alternator: ~1.2–1.6 kW

Planned upgrade:

secondary alternator → 6 kW continuous charging

 

Control & KFG integration

 

I developed a custom communication module for KFG, OEM-fit, which:

• switches interior and exterior lights
• controls the water pump
• controls the awning
• integrates additional functions without errors in the OEM system

For KFG, everything behaves like factory hardware.

 

Water system

 

– upgraded water pump
– grey-water tank:

• insulated
• heating pad
• mechanically protected

– electric drain valve, controlled from the dashboard
– dedicated camera to see exactly where the tank is being emptied

 

Toilet

 

– Clesana C1
– complete elimination of chemicals and smells
– clean integration, no space compromises

 

Heating & air distribution

 

– redesigned hot-air ducting
– proper heat distribution to the rear
– front and rear comfort now match

 

Audio & noise reduction

 

– sound insulation: front doors, sliding door, rear doors
– true 3-way audio system, enclosures calculated to manufacturer specs
– dedicated amplifier + DSP
– subwoofer with independent control
– major improvement in driving comfort

 

Lighting

 

– OEM LED strip replaced with a digital LED strip
– ON/OFF via OEM display
– colors and scenes controlled via my own app

 

Connectivity

 

– 5G modem, easily accessible
– Starlink for areas without mobile coverage
– stable connectivity for remote work

 

Cameras & exterior

 

– 1080p rear camera, OEM-fit for the large display
 

Awning & step

 

– longer awning, extending past the rear window
– electric operation + app control
– new step with a control module that perfectly simulates the OEM step for KFG

 

General principle

 

I avoided drilling the van wherever possible. Where drilling was unavoidable:

• custom ABS parts, OEM-fit
• body protection
• VW-recommended sealant

 

What’s next

1. secondary alternator (6 kW)
2. rear furniture reconfiguration:

• daytime: sofa / lounge area / nighttime: full bed, no compromise on sleep quality (same or better than the current setup)

 

Questions, criticism and ideas are welcome.

 

Because of forum limitations, I can’t include everything in a single post (photos).

I will therefore add separate follow-up posts, each with photos that relate to the topic.

[Bizzaru]

Insulation & structure 

 

OEM insulation: 

You do not have the required permissions to view the image content in this post.

 

Rebuild insulation: 

All the walls doors and roof top have been reinsulated.

 

[Bizzaru]

Electrical system – EcoFlow Power Kit

 

You do not have the required permissions to view the image content in this post.

[Bizzaru]

Photos & gallery note

Uploading photos directly to the forum is quite slow and limited, so I will create a OneDrive photo gallery where I’ll upload all relevant pictures in full resolution.

[MarioRS]

Servus Bizzaru,

 

very impressive, thank you for sharing!

 

Do you offer such a reconstruction, or partly optimisations, professinally or is this a solely private improvement project?

 

Greetings from Vienna, Mario