Factory Auxiliary battery wiring

[Rob.P]

Hi.
I have a the set up as shown in the photos and would like some info if anyone can help please.

• Where does the feed into the split load relay come from as it is not connected to the battery terminal, and what might be the length/ route for the cable? I would like to fit a proper leisure battery under the drivers seat and wondered if I can use the existing feed cable but can't work out volt drop without knowing the length.
• Does anyone know what the 40a fuse does? It's nothing to do with the aux battery.
• 80A seems a bit high for 10mm? cable doesn't it? I haven't actually checked its current carrying capacity.
• The small cable coming from the battery terminal feeds the 12v socket on the top of the dash but why no fuse at the battery end? Just sloppiness from VW?
• Some of the battery to battery split load relays are 20/ 30A is this sufficient and what difference does the higher current make, faster charging? Should I base my cable calls for the existing cable on the 30A relay.
• There are 2 smaller wires on the relay, I assume to switch the coil. Can anyone tell me where they get there signal from.

Sorry for all the questions. I'm sure there will be many more if I go for the leisure battery.

 

[Dellmassive]

That looks like the OEM split charge relay setup.

The main feed comes from the SA fuse box under the starter battery.

It feeds the relay via the 80A fuse and that 100A relay.

The leisure battery will self limit the drawn current as a SLA battery.... so you won't see 80A or anything, more like 20-30A drawn from the engine bay.

The relay control signal comes from the BCM.

More info here...

[Guide] DC-DC Charger (for leisure battery) -- How I Done It --

DC-DC Charger (for Leisure battery) -- How I Done It -- ************************************************** Dellmassive`s -- "how I Done It" -- Thread ************************************************** Kit List And Stuff -- How I Done It & What I Use --...

www.t6forum.com

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[n10n]

• Does anyone know what the 40a fuse does? It's nothing to do with the aux battery.

It will be either electric slider, if fitted, or rear aircon blower afair

• 80A seems a bit high for 10mm? cable doesn't it? I haven't actually checked its current carrying capacity.

If the batteries are in very different voltage when connected the momentary amps will be high. Wire load ratings are for continuous current.

• There are 2 smaller wires on the relay, I assume to switch the coil. Can anyone tell me where they get there signal from.

Brown will be ground, afair connected to earthing point in the floor under seat base where a bunch of wires go. The other one is engine run signal from BCM.

 

[roadtripper]

Sorry for all the questions. I'm sure there will be many more if I go for the leisure battery.

I'm a little confused by this point... You appear to already have a leisure battery?

 

[Rob.P]

It will be either electric slider, if fitted, or rear aircon blower afair

I don't have either of those.

I'm a little confused by this point... You appear to already have a leisure battery?

It's a 70ah Moll battery, I think I would prefer a bigger battery, fitted under the drivers seat (as I may get a swivel base for the passenger) and with the option of adding 230v and solar.

 

[n10n]

I don't have either of those.

Webasto? I remembered rear blower but was really front one when factory webasto installed. Or the external use interface if such is fitted.

 

[roadtripper]

It's a 70ah Moll battery, I think I would prefer a bigger battery, fitted under the drivers seat (as I may get a swivel base for the passenger) and with the option of adding 230v and solar.

Many people have a swivel base and a full setup under it. Probably more likely to find batteries under that side where the factory ones are than the the other.

Given the high current wire is in place I'm not sure what you'd gain by striping the van down to take it out and put a longer one in to the driver's seat base?

You should have space to get a DC-DC charger in fine even with a larger battery. If you go LiFePo you'll get more capacity in the same space. If you need space for an inverter then you can put additional high current cables between the bases with much less disruption (you may even be able to fish them across) which is what the factory fit inverter in the drivers seat base does.

The wiring diagram for the factory non camper battery is here if you have VIP membership

T6 - Aux Battery (non camper) Wiring Diagram

Second battery wiring diagram for factory fit underseat batteries This covers panel vans and kombi vans, not applicable to any California nodels VIP Membership is required to download this document

www.t6forum.com

The only other thing I can see using a 40amp fuse from the factory in that fusebox that has not been mentioned is the "interface for external use" - is the van an ex fleet van that might have had additional equipment in?

T6 - Interface For External Use Wiring Diagram

Interface For External Use IS1 IS2 IS7 Circuit Diagram Covers interfaces IS1 IS2 IS7 for vehicles with engine codes CFCA CJKA CJKB CXFA CXGA CXGB CXHA Please check the history/updates tab, first release is for early T6s manufactured from June...

www.t6forum.com

 

[Rob.P]

Webasto? I remembered rear blower but was really front one when factory webasto installed. Or the external use interface if such is fitted.

I wish. That's another thing on the wish list (not necessarily a Webasto).

The only other thing I can see using a 40amp fuse from the factory in that fusebox that has not been mentioned is the "interface for external use" - is the van an ex fleet van that might have had additional equipment in?

No. It's a 17 plate DSG panel van.

I don't have VIP but will look at getting it so I can see all the documents.

Many people have a swivel base and a full setup under it. Probably more likely to find batteries under that side where the factory ones are than the the other.

Given the high current wire is in place I'm not sure what you'd gain by striping the van down to take it out and put a longer one in to the driver's seat base?

You should have space to get a DC-DC charger in fine even with a larger battery. If you go LiFePo you'll get more capacity in the same space. If you need space for an inverter then you can put additional high current cables between the bases with much less disruption (you may even be able to fish them across) which is what the factory fit inverter in the drivers seat base does.

I quite like the look of the Easy spinner base and that allows the seat to move positions backwards and forwards which I'm pretty sure wouldn't be compatible with the battery set up in the passenger seat. I was hoping to extend the cable to under the drivers seat which would only add a metre of cable at most, hence the question about length of run to ascertain volt drop. I would need to remove the passenger seat to fit the base anyway and stuff all the cabling under the mat so it would only mean taking off the drivers seat.

That looks like the OEM split charge relay setup.

The main feed comes from the SA fuse box under the starter battery.

It feeds the relay via the 80A fuse and that 100A relay.

The leisure battery will self limit the drawn current as a SLA battery.... so you won't see 80A or anything, more like 20-30A drawn from the engine bay.

The relay control signal comes from the BCM.

Thanks Dellmassive, I will have a proper look at your 'How I done it'. Do you know the size of the fuse under the starter battery and whether it would be feasible to extend the existing cable to under the drivers seat to feed a 30A B2B charger?