Halfords Combination Relay

[kefty]

Hello
I have bought a leisure battery 110Ah (£60 from Go Outdoors) and I have bought one of these Halfords(£16.99) but the wiring diagram does not have an additional battery. Its purpose is a combination relay for split charging aux battery & fridge supply (says on the back of relay) and there are 5 wires
1 - purple
2 - red
3 - light green (with inline fuse rated 15A)
4 - black
5 - dark green.

My leisure battery is in a special made box behind drivers seat (right next to starter battery), I think this is the best place for it. On searching Wiki/www I find that normal relays have 4 connections labelled 85,86,87,30. Mine has the above 5 connections/wires. Does anyone know how to wire these up as the diagram provided is crap. (there isnt a blue wire etc!)

Advice gratefully received. Im sure it isnt very difficult its just the wires here are all labelled differently. The Halfords part is
http://www.halfords.com/webapp/wcs/stor ... ryrn_38191
Thanks for reading
Kefty