Oh yeah I'm still around just don't own an X5 anymore So I don't follow up on this forum.

Got this message in my inbox at work.

The ARB compressor connects using crocodile clips, 1 to positive terminal in your engine bay and the other to any earth point. They have an on/off switch but automatically turn off when the small tank pressure get to 80psi. They also have a fuse. There it won’t cause any issue with electrics on the car.

Cheers, Wally.

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Cheers Andy
From Down under

2004 4.4i Sport Alpine White
2008 Toyota Land Cruiser Turbo Diesel (on order)
1993 Daihatsu Feroza SXP II