Harv wrote:

I believe Richards caution is wise. Eg, if you try to draw 200A from a 150A alternator, I think the alternator will try to supply 200A even though it won't be able to, and you risk burning the alternator up. If you are only at idle, the alt may not be turning fast enough to burn itself out, so you may be okay. Having said that, I see people using their winch with the engine running reasonably often, so the danger might not be that high.

But you won't be drawing 200A direct from the alternator if you've got even the main battery connected (which you will as it's obviously wired into the vehicle). Some of the current draw will come from the battery.

If you were purely loading up the alternator then surely any vehicle with a winch would require a dedicated battery to run it so won't burn the alternator out?

The factory winch for a P38 was a Warn XD9000 or something along those lines and the current rating on that is over 400A at max line pull. The specs for it recommend a minimum 650CCA battery for winching, but again in the LR fitting documents, there's no talk of requiring a second battery to run it - even on the earlier GEMS vehicles where they had a 120A alternator.

As I mentioned, I put a second battery/split charge in mine in the thought that at some point I'd fit the winch, once I found one I liked and would fit, but not because I was worried about the current capacity, but more to give the system a helping hand and I wanted to run other things off of it too.

Thanks for the reply Marty. It sounds like I shouldn't worry much about it. So far I only have a winch on my Series 2, none yet on the P38 or Disco.

Is it unadvisable to run the cable(s) along the chassis in flexible conduit from front to back? My grommet on RHS is getting rather full i cant see it taking another 2x25mm cables now...

The cables that plod ran in on mine when they installed the aux battery are attached to the inside of the RH chassis rail. Admittedly, the drilled holes in the boot floor to bring them up into the RH corner and the aux battery was fitted there.

Hi crowd,
just to let you know the silence is just because I needed to order most of the things, here nothing that specific is available quickly (or reasonably priced). So now I am waiting for: t-max split charger, an anderson-type connector, the "megafuses" and holders (and spares! just in case O_o), and also a small fusebox/relaybox so I can put the stuff I want in relative order.

In the meantime I am sorting out the issues, first being due to my LPG tank I have very little space in the (former) spare wheel area, I might need to check for some of these strange shaped AGM batteries, might be expensive but ... I don't want the battery in the boot, I already got enough clutter planned there.
Second one is the section of the cables, being electrically illiterate I am having some issues understanding the (easy, for others) simplicity of the cable sections vs load. This to better guess what cable to run to the rear.
I got some meters of these two to use:

The red one I have loads, it is the one that takes power to the fusebox in the old audis. Not sure I can figure out the section, but the diameter of the copper is between 5-6mm. The black one is the ground to the battery from the engine bay area, so it is hefty, at least double.
I am sure you will tell me to use this one ... :-) In that case, does it make sense to run one cable inside the car (say the "+") and another (say "-" attached to the chassis rail?) I already have other wires to pass and don't have enough space ...

I will continue updating here so we keep all the info in one place.

Assuming fine cored flexible cable, if the diameter is 5-6mm, then the cross sectional area will be Pi x r squared, so roughly 20mm (3.141 x 2.5 x 2.5) which is rated at around 135A (see https://www.autoelectricsupplies.co.uk/product/752/category/124).

OK got the point. Will wrestle big black anaconda to the rear ...

Very little progress on this, I was stuck elsewhere in the car ... now, some advice - again - before I start cutting cables ....
Some opinion on positioning the split relay ... I have my ideas, but rather hear yours:

1 - side of the battery, inside the battery lid

2 - rear of battery tray/box

3 - side of battery box/tray

I also got a relay/fuse box to add the connection to the additional consumers not making unnecessary clutter ...

Which also need a place to go .... surprising not much space around the V8 engine bay.

4 - side of the battery box/tray

5 - rear of battery box/tray

My biggest problem is the relay box, option 5 requires I make a mount and it is too exposed to heat, and there it bothers other stuff (LPG, etc.).
Option 4 means for everything and anything battery needs to come out (no dramatic deal), but it is way neater, and closer to the main fusebox to keep cables in order. Might bother if I fit the relay close by though ...

Plod made up a bracket and mounted it to the top of the suspension turret for the extra fuses, relay and split charge relay. It has also been used to mount the Pitagora injector emulators for he LPG system.