PROJECT 4, Dual battery set-up for a Defender ( & other 4x4s )

**Stepho_62** · 3rd January 2007, 07:38 PM

G'day

Drivesafe and Blacknight would be probably the men to answer this correctly technically but from a laymans terms this is my interpretation.

Firstly let me say that this is no longer a necessary option. With 12v Batteries giving out up to 900 Cold cranking Amps that I know of dual sixes are just not necessary.

Having said that, I recently sold an ll metre cruiser. This was powered by a 120 HP Sabre Marine converted ford 2715e 6 Cylinder diesel. At about 365 cubic inches and with a compression ratio at about 16 / 1 it need some serious cranking capacity to start it.

Now we are not talking about average available amphers here BUT what is know now days as "Cold Cranking Capicty or CCA.
from 1958 - 1973 when these engines were built the ol 12 volt battery just wasn't up to it, so they used 2 x 6 in series to get the necesesary cranking capacity.

The other issue they faced was that these engines DIDN'T have any glow plugs. They used a mechanical system which is known as "Flood Starting, Cold Feed, etc etc etc. No doubt Black Night or one of the other experts can give u the technical details but the upshot of it all was that when you used cold feed start it effectively put a measured amount of diesel into each cylinder to flood it and there by raise the compression ratio even further to get the bugger to start.

The upshot of this approach was its dead simplicity. An engine in good nick simply didn't need cold feed to start it unless its injectors were dodgy or it was down on compression.

In th 4 years I had Knot Accountable,

I only once used the cold feed start switch on th injector pump and that was becasue it was around 0 degrees

in the engine room.

Hope this helps, Cheers

**numpty** · 5th January 2007, 02:03 PM

Originally Posted by Stevo_62

Numpty,

I've done the same. I was going to run an independant earth for the AGM 2nd battery. Then thought WTF for?????????????????

. Its unlikley its ever gonna get 1400 CCA through it. If it does the bloody chassis rail will melt first

Actually, when I did the initial setup in the Stage 1, I used the original chassis earth and would occasionally have no power. Was advised by Auto Elec to earth to engine or gearbox, which I did, and never another problem. I just used the standared earth connection on the Defender, wherever that earths to.

**Stepho_62** · 5th January 2007, 07:11 PM

Originally Posted by numpty

I just used the standared earth connection on the Defender, wherever that earths to.

Thats the one that goes to the Chassis rail and then on to the engine/g/box earth.

**Koukandowie Brangus** · 8th January 2007, 03:08 PM

Shoe horn!! thats and understatement, more like a crowbar!!! check mine out that i did a couple of weeks ago

I put that rubber mat over the lot to stop a backhand across the head if the missus ever got electroshocked if the terminals touched her seat!!

**drivesafe** · 8th January 2007, 05:03 PM

That’s a nice neat job TREX.

No comment on the backhander

**George130** · 8th January 2007, 06:21 PM

Wish mine was that neat!
Can't work out what wires are what. I have been to afraid to clean up the mess they made incase the beast stops working.

**Jamo** · 11th January 2007, 10:22 AM

Here's a pic of my Aux battery with the SC80 fitted (not as neat as the TREX's, but the best I could do in a tight spot).

**drivesafe** · 12th January 2007, 05:19 AM

Hi Jamo, with that size battery, it looks like you could not use the Land Rover battery brackets and bolts.

How did you manage to fix the battery in place.

I also see you found the perfect mounting place for the controller. If I didn’t know better, I’d say LR made that just for the SC80.

Cheers

**Jamo** · 12th January 2007, 07:56 AM

The battery has a metal jacket around the sides and bottom. Plates have been welded to this in order to utilise the existing fixings.

I'll get back to you as to actual details as I'll go and see the bloke who supplied the battery in the first place. You could still use the LR Brackets I suppose.

Yes, the controller fits in nicely. And thus far (albeit one week) the battery has maintained charge so I'm hoping that the charging problems I experienced were associated with the TJM controlled that I had before.

**geckos** · 12th January 2007, 05:18 PM

These are mine for all to see. It was fitted before christmas. A mate (A LECCY) helped with cutting the wires right length and heat shrinking. The soleniod is Smart Start from Redarc. No problems so far.
The batt holder is OE and the batteries sit in on an angle due to the shape of the floor of the battery box.
Any more questions just ask????????
http://www.aulro.com/afvb/attachment...6&d=1167528622
Enjoy geck

PS sorry about the blurry pic

Thread: PROJECT 4, Dual battery set-up for a Defender ( & other 4x4s )

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