Auto electronics

[Mattius]

quick question about car electrics.

i have an old fashioned style racing electric cut off, you know the red key type, what i want to do is allow enough electricity for the radio to save its presets etc. now my thinking is if i bridge a wire accross it with a 15amp fuse, if the ignition is tried without the cut off key the fuse will blow and nothing will happen, yeah?

 

[agw_01]

Yep, that sounds plausable

Or you could just wire the perm live from the head unit to another perm live in the car... or maybe even directly to the battery.

 

[Mattius]

there is no live wire in the car, this cut off switch cuts off all electrics, for obvious racing reasons, now its just a handy kinda imobiliser.

 

[pinkaardvark]

Seems like you have a switch that does a job you don't want doing. Isn't it easier just to remove the switch, or just connect it to the ignition feed if you just want an immobiliser. Of course a big red switch in plain view can't be that effective as an immobiliser

 

[Mattius]

its a classic car, i like the retro style switch and it works perfectly

 

[Jonny69]

I think you might have to play with the fuse rating as 15A is probably enough to run a lot of the car on. If it is a direct cutout on the battery and the starter motor goes through it then 15A will be fine as cranking the engine over will blow the fuse. If it doesn't crank through the cutoff switch then the engine will start and run fine through a 15A. It will only blow if you put the lights on as well, which again might not quite add up to 15A when you take the alternator/dynamo (ninja classic car edit!) current into account. You probably want closer to 3A or 5A max I would have thought.