Thread: 12S Socket 30amp Battery feed; is it a hoax?

Background
I have a 2008 RRS (Disco3) to which I have fitted Tim's Traxide dual battery system with a 50amp Anderson plug to the rear bumper and a permanent 25amp supply to two 12V sockets in the cargo area (Traxide designation D3-Kit-DS). The 25amp circuit replaces the ignition switched 12V socket in the cargo area, and ?frees up? the switched supply that powered the single standard socket setup.


Hardware
Our caravan has two Anderson plugs fitted. The first connects to the 50amp plug on the RRS and it charges the 2 x 110 AH house batteries. The second Anderson plug is to run a Dometic 3-way fridge which will draw 22.9amps at 12V, and to also maintain the breakaway Brakesafe battery.

Assumptions

• Pin-4 on the 12S socket is a 30amp permanent feed
• Pin-4 feed is via the F8 fuse (fuse box under glove box) labelled ?Trailer Pick-up (Battery Feed)?
  Pin-3 is the earth for Pin-4
• The ?Freed-up? switched supply (from the Traxide kit install.) could be used to convert Pin-4 to a switched feed via a 30amp relay

Problem defined

• System seemed to work fine for a about 10 seconds, but then died.
• F8 30amp fuse checked and found to be good. Mystery!
• Blue cable with pink trace looks too small for 30amp.

Attempts to fix

• Had several attempts which involved ripping out most of the cargo area trim ? getting good at that at least!
• Called Tim and discussed at length possibility that there might be a cable problem in the loom somewhere between the fuse box and the 12S socket.
• After yet another attempt, disgusted I went inside and attacked a bottle of Glenfiddick
• At the end of the next session later that night I replaced a battery feed fuse (3) in the tow hitch box
• The following morning (after having re-attached all trim, and declared eventual defeat the night before) I couldn't resist getting out the multimeter again.
• Having already forgotten about the 15amp fuse I replaced the night before, I discovered I had 12.6V on the battery side of my relay control to Pin-4.
• Got out the portable compressor and attached to the 12S socket and started the engine of the RRS. Switched on the compressor and it ran well ? for about 10 seconds, and then stopped. All was dead.
• Still not attaching any significance to the aforementioned replaced 15amp fuse, I immediately checked the 30amp F8 fuse, which I found to be in as-new condition.
• Then, it dawned on me that the much publicised and talked about 30amp battery feed to Pin-4 might have always been a 15amp feed. And it is?

Conclusions

• So I have, as have many others, believed wrongly that a 30amp live battery feed is available at Pin-4 of the 12S socket. May be it is in other Land Rover flavours, but for my RRS it is not a 30amp supply: and I suspect it isn't on any LR either.
• Having arrived at this conclusion already, starting a new thread might be seen as superfluous, but on the other hand, given the grief that this issue has caused me, and many others here and possibly also in other markets, I reckoned it would be worthwhile to post it.

I would be interested to know if others had arrived at the same conclusion.

Next Step
I will now install a separate 6B&S (or maybe an 8B&S) cable from the Yellow Top auxiliary battery to another 50amp Anderson plug. I will locate a suitable relay/solenoid in the driver's side rear quarter panel, where I have the existing 30amp horn relay performing the same function on the now abandoned ?30amp? Pin-4 supply on the 12S socket.

Footnote
When I started writing this post it was to seek help to getting the 12S Pin-4 to deliver 30amps. A thought that briefly flashed by me was that the factory had made a wiring error, but of course they hadn't. The error was mine, having too eagerly accepted the conventional, or crowd, wisdom that the 30amp Pin-4 feed was correct. I had looked at the 30amp F8 fuse marked trailer feed and simply assumed it was the feed to Pin-4 of the 12S socket.

When I look back I have never seen any official LR reference that there is a 30amp battery feed on the 12S socket. But I saw many references and assumptions in numerous posts here and in the UK, and elsewhere, that it was a fact, which I accepted as factual; accepted without question.
This, I think, is quite a good example of not looking for the simple explanations first. I have found it instructive; I hope other Aulro members do too. And if not instructive, then may be mildly entertaining!

John ?

PS: There seems to be a fairly common but false belief amongst many Disco/RRS owners (including me) that there is in fact a 30amp live battery feed to Pin-4 of the 12S socket. As an example only, refer to Muddy Diver's post of May 2013:
http://www.aulro.com/afvb/d3-d4-rrs/...ml#post1920062

Originally Posted by LandyAndy

Did you have the engine running whilst testing????
The ECU shuts the ignition off after a short time if its not running,could explain why it goes "dead"
Andrew

Yes, I had the engine running. But thanks, I did not know the ECE shuts the ignition off the engine isn't running.
John