Additional under seat power / fuse box

[Paynewright]

Hi

I’ve done some searching already and cannot find an definitive answer to my question. Also, sometimes a new thread can draw out very specific answers so here goes.

My van is a 2018 Startline window van. It is very basic, perhaps too basic, so I’ve been adding additional electrics. So far I have 4 piggy back fuses in the lower centre dash fuse box. Dash cam, 2 x USB and a rear 12v outlet in 4mm cable. This feels a little wrong and un sustainable!

There are no thick red cables under either seat.

I need to install tow bar electrics which head for underneath the passenger seat.

At some point in the future I may want to install a second battery and/or solar.

I’m looking for a solution that deals with the current and caters for future adaptations.

My current (no pun intended) thinking is to route a thick fused Permanent live cable (30 or 50A) from the unit under the battery to under the passenger seat. Install a fuse box with perm and switched live sections (using dashboard switched signal feed) then run all new circuits from there. Hopefully this will satisfy the towbar feeds. Also, I’d like this to be phase 1 of subsequent additions ie split charging and solar feed.

Can anyone advise what I need to do and materials needed, particularly the connections / fuses to the main control unit under the battery?

With these complex upgrades its often good to chat so send me a message if you are willing to receive a phone call.

Thanks

Ian

 

[The Bear78]

'Afternoon.
I was in the same position as you. Nothing under the seats, towbar on its way and no desire to fill the fusebox with piggyback attachments!
I did what you have suggested and added a feed directly from the OTO fuses (if that's what they're called) under the battery. I actually had enough cable to make two so I added a spare for future requirements. This feeds a fuse box under the passenger seat which distributes power via relays as I currently have no leisure battery. The relays themselves are activated via a piggyback fuse from the ignition live centre row. The relay coils draw very little current so I can activate several circuits from just one piggyback.
I am planning to fit a leisure battery soon and will use the battery feed for the Dc-Dc charger and the new fusebox will just run from the leisure battery instead.
A few points/mistakes I made:
- There are ignition live connections under the battery so I needn't have used any piggy backs.
- make sure you fuse any battery feeds as close as possible to the battery to protect the cable run
-the westfalia towbar kit will go under the seat and can be powered from this feed (as I have done). However, the loom is designed to go under the van to the battery then aacrossthe engine bay and back into the BCM connectors. It isn't ideal running the cables from underseat to the BCM although obviously it can be done.
- if you plan on fitting an EHU under the bonnet now would be a good time to do it as the cables can share the route back through the bulkhead.
- I used 6mm sq cable from the battery as recommended by travelvolts. This is rated to ~48amps and fused to 30 amps. This is enough for all of my consumers, especially as I have two, but may not be enough for larger DC-DC chargers on its own.

This is the kit I used:
6mm feed

 

[Paynewright]

'Afternoon.
I was in the same position as you. Nothing under the seats, towbar on its way and no desire to fill the fusebox with piggyback attachments!
I did what you have suggested and added a feed directly from the OTO fuses (if that's what they're called) under the battery. I actually had enough cable to make two so I added a spare for future requirements. This feeds a fuse box under the passenger seat which distributes power via relays as I currently have no leisure battery. The relays themselves are activated via a piggyback fuse from the ignition live centre row. The relay coils draw very little current so I can activate several circuits from just one piggyback.
I am planning to fit a leisure battery soon and will use the battery feed for the Dc-Dc charger and the new fusebox will just run from the leisure battery instead.
A few points/mistakes I made:
- There are ignition live connections under the battery so I needn't have used any piggy backs.
- make sure you fuse any battery feeds as close as possible to the battery to protect the cable run
-the westfalia towbar kit will go under the seat and can be powered from this feed (as I have done). However, the loom is designed to go under the van to the battery then aacrossthe engine bay and back into the BCM connectors. It isn't ideal running the cables from underseat to the BCM although obviously it can be done.
- if you plan on fitting an EHU under the bonnet now would be a good time to do it as the cables can share the route back through the bulkhead.
- I used 6mm sq cable from the battery as recommended by travelvolts. This is rated to ~48amps and fused to 30 amps. This is enough for all of my consumers, especially as I have two, but may not be enough for larger DC-DC chargers on its own.

This is the kit I used:
6mm feed

How did you connect the cable - is there a threaded post?
Do you have any pictures of the install and links to other components you used?

Thanks

Ian

 

[The Bear78]

Yes there are several threaded posts, most were taken on mine but two were spare. I wish I took a photo as I've only seen one picture on here which is odd considering how often it gets mentioned.
Il try to find it....

 

[rod_vw]

Run the cable to the BCM along the route of others under the front floor covering. It's not too easy but I think better than going into the engine bay.

 

[The Bear78]

E-box fuse bar...

 

[rod_vw]

I was under the impression that fuse 3 was the one for second battery connection BUT check this with the correct diagram for your vehicle.

 

[The Bear78]

It's a generic pic from Google...
The fuse assignment list is here in the VIP resource area.

 

[Paynewright]

That picture allays any fears! I cannot seem to find those bolt in fuses. I live near a company called Multicell who sell batteries - they also make up heavy duty battery cables with proper crimped ends.

Just need to work out what equipment to fit under the seat - mix of perm live and ignition live feeds.
Thanks
Ian

 

[The Bear78]

This is mine, semi finished. The space will be filled with DC-DC and mains charger eventually. I intend to fit the leisure battery under the driver. If I had put the consumer unit under the bonnet I would have probably had room to fit it all under one seat. I intend to use the EHU on campsites though rather than just at home so I chose the bulkier double MCD version for extra peace of mind.

• The live feed is the currently taped fat red cable.
• The red/grey cable on the fuse box input is the PF Jones trailer kit.
• The earthing block (all black cabling) has a large 6mm cable back to the factory earth point underneath.
• The thin red cable coming out of the hole is the switched ignition live which energises the relays.
• The unused MCD will feed the mains charger once fitted.

 

[rod_vw]

That picture allays any fears! I cannot seem to find those bolt in fuses. I live near a company called Multicell who sell batteries - they also make up heavy duty battery cables with proper crimped ends.

Just need to work out what equipment to fit under the seat - mix of perm live and ignition live feeds.
Thanks
Ian

Ian, do you mean that you can't find a supply of that type of fuse or do you mean you haven't found the 'E' box?

If it's the latter, take the engine battery out, take the plate that it sits on out then remove the big plastic lid, all will be revealed.

 

[Paynewright]

Ian, do you mean that you can't find a supply of that type of fuse or do you mean you haven't found the 'E' box?

If it's the latter, take the engine battery out, take the plate that it sits on out then remove the big plastic lid, all will be revealed.

Yes I know where the ebox is - it was the fuses I was struggling to find. As always it was the key search words that helped find them.

Its hardware I’m researching now - fuse boxes, ignition switched supply.
Cheers

 

[rod_vw]

Sorry Ian, I didn't mean to doubt your knowledge but thought the location may be useful to others.

I've used AES and Vehicle Wiring Products for electrical parts and cable in the past.

The control signal for what VW use as 'split charge' is in my opinion best picked up from the BCM which I think is still T73a/3 but do check for your year vehicle. You can find complete wiring diagrams (and everything else) at Volkswagen Transporter 2016-2020 Workshop Manuals + Wiring Diagrams | Free Download

Good luck with the job.

Rod

 

[Paynewright]

Sorry Ian, I didn't mean to doubt your knowledge but thought the location may be useful to others.

I've used AES and Vehicle Wiring Products for electrical parts and cable in the past.

The control signal for what VW use as 'split charge' is in my opinion best picked up from the BCM which I think is still T73a/3 but do check for your year vehicle. You can find complete wiring diagrams (and everything else) at Volkswagen Transporter 2016-2020 Workshop Manuals + Wiring Diagrams | Free Download

Good luck with the job.

Rod

Rod,

Those sites are really useful - thank you.

Regards

Ian

 

[rod_vw]

No Problem Ian, I converted my first camper in 2004 now driving my fifth conversion but been a camper owner since 1977 so I've had to do lots of research over the years.

 

[Paynewright]

No Problem Ian, I converted my first camper in 2004 now driving my fifth conversion but been a camper owner since 1977 so I've had to do lots of research over the years.

You might regret telling me that

 

[rod_vw]

That's exactly why many of us belong to these forums, it's all about helping one another out.

The Historic Volkswagen Club exists to do just that for a different section of the VW owning fraternity.

 

[Paynewright]

That's exactly why many of us belong to these forums, it's all about helping one another out.

The Historic Volkswagen Club exists to do just that for a different section of the VW owning fraternity.

I’ve been a member of the Lotus seven club for 22 years, having built my Caterham Seven in 1998. I contribute a reasonable amount to the technical forum. The demographic has changed significantly from enthusiastic home mechanics to ‘lifestyle’ ownership so we get lots of ‘how to’ questions from people with very limited DIY experience. At the end of the day they are just a big meccano set so nothing too difficult.

I was lucky my father taught me how to take things apart and fix stuff!

Ian

 

[The Bear78]

I've owned a van since December 2019 so I'll gracefully bow out now....

 

[rod_vw]

I've owned a van since December 2019 so I'll gracefully bow out now....

Don't worry, every day is a school day as a VW owner. The person who knows all about VWs ain't been born yet, although there are a few who think they do.

And just when you think you have a reasonable grip on things VW grease the pole!