Wiring a duel battery solenoid

Hi Folks,
Put me out of my misery please. Setting up a duel battery system in my GU 2001 3ltre auto, with the cost restraints imposed by the better half have purchased a solenoid as per attached pic. I have done a search but stuffed if I can find any info on how to wire it. The large terminals presumably are for battery connection, what are the smaller ones? Connection from ignition and earth ?. Also without destroying the wiring loom what is the easiest way to obtain a connection when the ignition is on, is there an easy connection point under the bonnet?
Thanks,
Baz

I wired mine up with the smaller terminals one to ignition on easiest is the diesel pump positive feed or coil positive if a petrol.
Then i run the other one inside the cab to a switch to earth as a bypass.
It actually lines up perfect with the pre done bolt holes on the side of the battery tray as well and the radiator shroud has tabs in it perfect for running the cable.
On the gq this is not sure about the gu worth looking at though.

Yes, large terminals are for you battery connections and the smaller ones are ignition and earth.

The easiest place to pick up an ignition feed on a GU is at the wiper motor.

yep wiper motor forsure !

Hi guys,
Just a query here about dual battery system.
Are you setting up a 'house' battery seperate from your engine crank battery?
or perhaps adding extra crank capacity.
Can you pls. clarify.

Ta lots
Dave.

No generally in Isolation. The second battery will take charge after the cranking battery has been charged to capacity. The solenoid is supposed to isolate the second battery accessories to avoid them from draining the cranking battery.

Hi, Thought I would post up the duel battery install to my 2001 GU 3lre Diesel Turbo, it may help someone in the future?
Firstly thanks everyone for advice much appreciated.
The battery tray I manufactured out of 1/8th ally plate incorporating a heat sheild fixed to the existing threaded bolt holes in the top of passenger side front guard, used spacers to level tray. Hold down is hinged metal strap with threaded rod and wing nut. (as per pic No.4)The live wires run along fire wall to keep them away from front of vehicle in case of accident. I took Yendor and Big Bells advice and sourced the ignition feed to solonoid from wiper motor (white cable pic No. 2) Earth from solonoid back to body but I will try 97-gq-lwb's idea of an isolation switch later on. Connected to the auxillary battery are, spotlights, also there was an existing connection to main battery for an Engel fridge in rear cargo area, modified a small junction box (upper left pic No.1) connected the fridge wire to same and ran a feed from auxillary battery. Plenty of scope for future connections. Baz