Someone else must have done this already. On my Fabia VRS, I want to control some accessories that need a good 12V supply, which suggests picking it up from the large plate on top of the battery. Problem is, this is unswitched, so whatever is connected is always live (and draining the battery).

Solution is to wire in a relay controlled by some under-bonnet source.

My question is - what did you use (or do you suggest) for a source? I'd appreciate it if you can suggest a location and the colour code of the wire (and whatever it is controlling)

Thanks - SteveP

how much current are you planning on taking??

you could wire up your goodies to the fuel pump relay.

another option would be to have a second battery and have a split charging system like they have in camper vans

I just need a "trip" feed to a relay - current would be just whatever the relay draws to hold it in - maybe 1/10th amp.

I'd prefer not to crimp a Scotchlok onto my fuel supply wiring :-) Something less critical but on with ignition and relatively close to the battery. Wiper motor? Washer pump?

a relay takes only a few milliamps to hold in on. but do bear in mind that most of the relays are permanantly live and require an earth (0v) to make the activate.

if you wanted to use the fuel pump relay, you dont have to crimpa scotchy to the wiring, you could just use one ofthe spare terminals from the fuel pump busbar on the back of the fusebox..

what device are you trying to switch on?? i might be able to work out what you are trying to do then??

It's a bunch of assorted stuff - I have a small sub wired into the hatch with power back from the battery. I also have some radio (as in two-way) I want to power and there may be others, so I'd like to have a good source.

A relay won't draw anything (if it is triggered by an ignition circuit) until the ignition is on.

I guess part of my problem is I don't know the ca that well (only had it a month) so when you say fuel pump busbar I wouldn't know where to look. That's whay I was asking for specific locations near the battery. I can futz about with a meter for an hour and find something, or someone could say "the blue wire in the connector to the washer pump" or similar. Thanks! - SteveP