Tombie, This had me concerned as ARB installed a bull bar and spotties so thought maybe they had ventured somewhere other than what I was shown. Had a closer look and the negative terminal all appears to be factory based on the youtube video here having the same arrangement JumpsPower AMG18 Jump Start New Land Rover Discovery 4 SDV6 3.0 Diesel - Real Performance Testing - YouTube. Had a look at the manual I had purchased and it does not show what the small connector on the negative terminal is however I recall being told that it had a shunt meter so maybe it is this.

