Dual Battery Configuration - VM Transit 2007

[davidkmckinney]

I have a VM Transit 2007 5. (MWB FWD) bought in Australia, with two batteries under the driver's seat.

Is there any documentation anywhere that describes how these batteries / 12v system is configured?

I want to use the aux 12v points in the van to run laptops and work (12 hours a day office setup) without running down the Starter battery. Can anyone confirm these points:

1. Starting the engine occurs solely from the Start battery (or does it need the Aux as well to start).
2. Start battery is completely isolated from the 12v sockets in the cabin and rear
3. 12v sockets in the cabin / rear run solely from the aux battery.
4. What other electricals run from aux (everything?)
4. is there a split relay / how is it setup / are there any diagrams
5. Which battery under the seat is the Start battery (rear or front). I hear conflicting reports.

Thanks
Dave

[ake]

Both batteries are connected for startup

The aux battery supplies 12v sockets, and most other loads, and at key off is isolated from the start battery

As far as I know the front battery only supplies the hazard warning light when key is off

There is a battery disconnect relay which disconnects the battery's, which is controlled by the bcm, there are diagrams in the BEMM which you can download from etis, however the way the control side is set up it is not something that can be modified by the user

The rear battery is the start battery

I do not think you will be able to maintain 12 hours draw from the aux battery for extended periods, the battery and the alternator will have a hard life. Also after a 12 hour discharge the battery will require a good charge, probably equivalent to a high speed run of at least 100 miles

[davidkmckinney]

Thanks Ake,
Great reply. That helps a lot.
Dave

[johnpietila]

Hi
I have a 2011 TDI 2.4 Transit van as a motorhome (in Queensland, Australia). Up till now I have not seen anything about the dual starting battery system. Has anyone in Aussie found e dealer who is FAMILIAR with these Transits?
Regards
JP
0421240241

[Jim Archer]

Sounds like you'd be better off running a leisure battery set-up.

Jim