Dual battery & on-board compressor install, Discovery Sport

[Johni]

Hi Nico,
So after many fruitless hours trying to find a grommet or hole in the firewall, I decided to cheat and use the rear fusebox in the cargo area instead. If you remove the cover; you will find blank slots with no fuse and a single terminal. In the middle and top of the grey segment there is a high current terminal with constant 12 Volt. The easiest way of tapping into this is to use a dual fuse tap (Jaycar part number SF5115, and for a mini fuse part number SF5125). I was a bit nervous that the current draw may be too high, but it is <25 Amp at peak (with a Redarc DC-DC convertor), and there is no excess heat in any of the wiring.

The tap for the switched 12 Volt can be found by probing with a multimeter in the blue section of the fusebox, the attached photo shows the point. Note that the power remains for about a minute after the engine is shut off.

The return negative/earth is all routed to the metal "U" section around the fusebox.

The whole setup has been stable driving daily for 6 months; with no error messages or other problems. The wiring and fusebox remains cool.Attachment 134927Attachment 134928Attachment 134929Attachment 134927Attachment 134928Attachment 134929

The attached photos demonstrate the fusebox taps, the voltmeter displays for starting and auxiliary batteries (while charging), and the completed setup with fridge and Drifta drawers. Please PM me if you want to go through things further.
Best,
Scott

Hi Scott
As I am busy with connecting up a 'live' 12V output from the fusebox in the cargo area, I discovered that it is the blue section of the fusebox that has the permanent 'live', and the grey section has the switched supply. Your article has them the other way around. I hope that I am correct?

[Scott_Parkes]

Just to post a revision here. The fuse tap I used for the main supply to the DC-DC convertor ran quite hot, so I have now taken the power from the main 12 constant input to the rear fusebox. This is the thick red wire alongside a lighter red wire with a blue stripe. Rather than cut and re-join the wire I removed 1.5 cm of insulation using the hot knife attachment of a soldering iron, wrapped the additional wire on the exposed segment, soldered and insulated with tape.

This has run cool since the modification, even when the auxiliary batteries are discharged.

Best
ScottIMG_0755.jpg

[Robbo DS HSE]

Hi Scott

I am new to the forum and was reading your installation with interest, having purchased a DS August last year.

I was wondering if the lithium batteries enclosed in the small space under the cargo area get hot while charging, and if you have arranged some ventilation to the area.

Regards

Ian

[Scott_Parkes]

Hello Ian,
The batteries are in fact Optima Yellow to AGM, each 50 AH. They run quite cool. When the trim and styrofoam padding around the spare wheel are removed, there is enough space for some air circulation, and there is a gap between the wheel well and the rear carpet, so there is some air exchange between the wheel well and the interior.
Best
S

[Robbo DS HSE]

Thanks Scott

I have run a 16mm2 cable from a VSR at the start battery to an insulated stud on the side of the spare wheel well, then a short 2x6mm2 lead to the stud and an body earth with Anderson plug on the other end for the fridge.

I was thinking of including some batteries to keep the fridge going when the motor is off, and liked your idea of using space below the cargo area

Thanks again

[Scott_Parkes]

Hello Ian,
Thanks. Did you run your cable from the engine to the insulated stud underneath the chassis? If you have some pictures, I would be interested to see.
Best, Scott

[Robbo DS HSE]

I will take some pictures next weekend

[DiscoMick]

I don't know anything about Discovery Sports, so I was wondering if you actually need a DC-DC. Can't you just link the two batteries through a DBC with thick cable and fuses?

[drivesafe]

Hi Mick, the problem with the Discovery Sport, like with the Freelander, up to now, no one has found a reasonable and safe way to get thick cabling to the cargo area, where the auxiliary battery has to go.

In this case, a DC/DC device has been the best option to charge the auxiliary battery. This is because while the current limit of a DC/DC device will cause a much longer recharge time, but it is a simple and SAFE way to use the existing wiring.

[DiscoMick]

Interesting. Can't it go down the transmission tunnel or underneath and up again? I didn't realise. How does LR send power to the rear lights?