Is this cable thick enough?

Hi John and sorry but that cable is not thick enough.

The reason you did not blow the 40 amp fuse is because the THIN cable run was so long that even if your two house batteries were dead flat, the voltage drop caused by the 8B&S ( 7.9mm2 ) cable would dramatically reduce the current draw of the batteries.

To increase the charge current a battery will draw, you MUST increase the voltage at the battery. 8B&S causes the revers.

I have seen house batteries draw 60+ amps down 6B&S ( 13.5mm2 ) cable, in the same situation.

For optimum charge performance, you should use at least 6B&S and while thicker cable would give better results, they would be very small improvements over 6B&S. So up to you!

With 6B&S, you can safely run 70 amp fuses but no bigger.

So just to be clear, running the ARB compressor, Waeco 50lt 12v, 65lt camper 12v fridge and keeping the 2 x 100ah of camper batteries charged will be achieved with 6b&s?

Quote:

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Originally Posted by John_D4

So just to be clear, running the ARB compressor, Waeco 50lt 12v, 65lt camper 12v fridge and keeping the 2 x 100ah of camper batteries charged will be achieved with 6b&s?

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I should have asked if the 65Lt fridge is a compressor type or 3 Way type.

If it is a compressor type then yes, the 6B&S will be fine.

If the 65Lt fridge is a 3 Way type, then you will need to run a separate supply, from the cranking battery all the way to the 3 way fridge and I would suggest using 8B&S for the fridge supply and fit a "Fridge Switch" to automatically control the power for the fridge.

Just to give you an idea of the difference the cables sizes make, I carried out some tests many years ago and this is what your can expect to get.

With a cranking battery voltage of 14.0v and a run 10m of 8B&S ( 7.9mm2 ) cable with a 40 amp load at the other end, the voltage was 12.09v. Just no where near enough to charge the batteries in any form of reasonable time. And forget the fridge.

With a 10m run of 6B&S ( 13.5mm2 ) cable and an end load of 40 amps, the voltage was 12.93v, and thats nearly a volt difference and would make for much faster recharging.

Even adding an additional load of 5 amps for the fridge, the 6B&S would be at 12.8v while the 8B&S would be down to 11.82v

Both fridges are 12v compressor fridges. I’m personally not a fan of the 3 way fridge.

For future proofing my setup in case I decide to go lithium in the camper (with a DCDC next to the camper batteries) when the 2x100lead acids expire, I’m wondering if 4b&s might be the way to go? Thoughts

Hi John and going up in cable size is never a problem, it is just cost verses outcome.

If you do not mind spending a little more, then do so.

Keep in mind that you will either need to reduce the copper thickness at the Anderson plug, to be able to use the standard 50 amp Anderson plugs or move up to 120 amp Anderson plugs.

Any idea what cabling route is possible for 4b&s in a D4? The existing 8b&s goes through the firewall grommet and out of the cabin at the rear drivers lights.

Quote:

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Originally Posted by John_D4

Any idea what cabling route is possible for 4b&s in a D4? The existing 8b&s goes through the firewall grommet and out of the cabin at the rear drivers lights.

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4B&S can go the same route.

I ran mine along the RH chassis rail then into the RH area behind the vent by using a hole behind the taillight into that area.

Mine is zip tied to the chassis and wrapped in split tube.

It terminates into a distribution block from 4B&S to 8B&S in there with 8B&S to the 2pin 50 amp plug to the caravan from there also through a hole drilled behind the taillight.
Regards PhilipA

Quote:

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Originally Posted by PhilipA

I ran mine along the RH chassis rail then into the RH area behind the vent by using a hole behind the taillight into that area.

Mine is zip tied to the chassis and wrapped in split tube.

It terminates into a distribution block from 4B&S to 8B&S in there with 8B&S to the 2pin 50 amp plug to the caravan from there also through a hole drilled behind the taillight.
Regards PhilipA

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In a D3, D4 and RRS of the same models, you should never run cable along the chassis rail, because if the vehicle has to have any work done on the motor or turbos, they lift the body off.

And when they do this, any cabling on the chassis rail is ripped out and if the cabling goes into the rear cargo area, it will damage panelling as well when the cable is ripped out.

It's a VERY expensive short cut, that is totally unnecessary because these vehicles are the easiest vehicles I have ever worked on to run cabling through the vehicle, WITH LAND ROVERS own wiring loom.

Do it right and save a lot of money.

Agree. I got confused by earlier references to D2.
Regards PhilipA