Dual Battery Options and Fitting

[Mtwem]

That’s good to know, hearing a lot of different things through word of mouth and good to hear that cheers

[John Deere]

I am not far from pulling the trigger on a T6 Transporter. It has the factory dual battery. Does anyone know how this system works? The dealers are pretty light on info, and it is only a $450 option with battery and "cut off relay" so I don't really know what to expect.

[Bryn23]

Ive got a 2017 model with the factory Aux battery, it was only a $500 option and at the time the dealer didn't now much.

It came with a 75 ah battery from memory, i measured the voltage into the battery while underway and it put out 14.55 volts (mine is a euro 5 engine)

I had swivel seats installed and the engineer replaced that battery without my knowledge with a 63 ah battery as the swivel module was close to the battery terminal.

I ended up, disconnecting the aux battery and removing it and installing a Votronic DC-DC/solar/230 volt charging system and installed two 140ah AGM in parallel in the rear of the vehicle under the camper bed

Its a camper and the max size AGM i could put under the seat was 100ah

If you only need a small amount of power, its handy, but if you are building a camper, you might need more Amp hours

but at $450... its worth getting if you need a Aux battery and don't want to pull the cab apart to run cables.

[Mtwem]

Thanks mate - was going to post an update tonight with photos of the setup as I completed it all pre Christmas and will go through how I did it - saved a lot of coin and was easy!

[John Deere]

So the factory dual battery is just a standard lead acid. Does it have a redarc style isolator to prevent backflow and discharging the main battery? Is there a switch to charge the main battery if it discharges? Basically is it like a traditional 4wd dual battery set up?

This is not much info about the isolating part.

[Mtwem]

Can’t say much about the factory battery but in regards to my AGM deep cycle - I purchased a DCDC charger that essentially is a smart isolator - once the charger detects the main battery has reached 100% ( also shown on the screen) it switches the alternator to charge the dual - and once it detects the main battery drops below 11.9 V ( I believe ) , which is when it knows the vehicle is off it stops drawing from the main and relies on itself.

Will post photos of what I did tonight

[Mtwem]

Battery setup under the bench seat.
I started here by cutting into the circular rubber grommet that sits in the middle of the floor.
From here ran cable and conduit under the car cable tying excessively to non mechanical parts and far away from the engine.
There is a pretty straight shot all the way to the battery bay.



Link to the MB.


Afterwards setup the DC DC charger which I mentioned above how it works.
All together the DCDC thunder charger and my 130AH battery were 500$ from an aussie battery supplier online.
Incredibly cheap and less than half the price a battery shop was offering me. 620 for a DC DC charger and 650 for a 120AH which i thought was crazy.





From the under the seat I drilled a hole and ran cable through to the above image where I set this thing up - 15$ off ebay and easy to set up.
Has my 12V plug on the left for the fridge and on the right are two USB ports for charging.
No hiccups and running smoothly since pre christmas.

Can send photos of the setup as well.
Overall it would've cost me close to 1200$ and about half a days work.
Saved a lot of coin versus going and getting someone to do it.

[Bryn23]

So the factory dual battery is just a standard lead acid. Does it have a redarc style isolator to prevent backflow and discharging the main battery? Is there a switch to charge the main battery if it discharges? Basically is it like a traditional 4wd dual battery set up?

This is not much info about the isolating part.

The battery is 75 ah Varta AGM, with vent tube, and it has a battery isolation relay.

Flick me you email via PM and ill send you the T6 Aux battery layouts PDF's that show the relay.

[drivesafe]

Hi folks and before you go fitting any form of DC/DC device, you should do a lot more research into what is available.

Even with EURO6 alternator operations, with STOP/START, you can get MUCH better auxiliary battery charging results by NOT using a DC/DC device.

I am not a sponsor on this site so I will not spam it, but do your research and you will find, if you do a fair bit of city driving, you can actually improve fuel consumption if you fit the correct type of isolator.

Whereas, fitting a DC/DC device may not only increase your fuel consumption, but it WILL take up to 4x as long to recharge a low auxiliary battery compared to what your alternator can do when connected directly ( via and isolator ) to your auxiliary battery.

[Bryn23]

A DC-DC will charge to 100% on a AGM and float the last 20%, the old school dual charging, never really got pass the 80% full mark

As for fuel consumption on a DC-DC, it wouldn't be much, it would be like not using the Air con, due to increased fuel use

Also the most DC-DC have MPPT solar regs with auto switching while driving and parked up, they also have different charging profiles for different volt's as well as steeped charging.

It looks like it would stress the alternator from the way i read it, and it isn't 4 times faster charging, in your website its 3.5 hours vs 5 hour approx?