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TB
21st March 2021, 04:39 PM
The Australian trailer wiring gives us a 30A direct line to the battery, which is there to support powered brakes on your van or trailer. If you’re looking at the plug on the car, the top right pin is the positive and the centre one is the ground. For clarity, both of those are in the row of five larger connectors, not the seven lower ones that take care of the trailer lights.

Given how demanding the L663 is on the starter battery, especially in the four-cylinder non-MHEV models, I plan to hook up a 6A charger via the trailer plug every week or so to try and extend the battery’s life.
Tombie
21st March 2021, 06:31 PM
I do that on my D4 regularly.

You can see it hooked in here.
https://uploads.tapatalk-cdn.com/20210321/14bdf7bb72c88888812c3a9847a2d60f.jpg
TB
21st March 2021, 07:48 PM
Didn’t know the D4 had the wires built in too! Thanks for that.
101RRS
21st March 2021, 07:54 PM
If you have the LR sockets fitted, so does the D3 and RRS.
dontwakemeup
25th March 2021, 04:00 PM
My defender has a factory towbar but only a 7 pin flat connector.
TB
31st March 2021, 11:02 AM
My defender has a factory towbar but only a 7 pin flat connector.

Are you sure? Get down there and take a peek, maybe a pic with your phone. The plug design has one row of 7 smaller pins which is a very common fitting for unbraked trailers in Australia, but there's a second parallel row of 5 larger pins which has support for the electric-assisted brakes.
TB
31st March 2021, 05:04 PM
It took only a few minutes to chop the SAE-to-alligator cable that came with my 6A smart charger and put a standard trailer plug on it. All working happily according to both the indicator lights on the charger and also the bluetooth voltage monitor I've attached to the battery terminals.

KT Cable Trailer Plug, Metal - Flat, 12 Pin | Supercheap Auto (https://www.supercheapauto.com.au/p/kt-cables-kt-cable-trailer-plug-metal---flat-12-pin/338969.html#q=12%2Bpin%2Bplug&lang=en_AU&start=1)

Something I found interesting: the Defender's factory-supplied battery is a 90Ah AGM, rather than the calcium type in my previous LRs. I guess being under the front seat is a much more friendly environment for an AGM compared to the engine bay where they are apparently prone to premature failure.
Tombie
31st March 2021, 05:20 PM
All D4s onwards are AGM

It’s more about charge capabilities