Is post 30 power supply fused by default?

[maxiz1]

Hello guys,
Just a quick question. I just switched the power source of my headlight relay from post 75x to 30. I thought it would be much more reliable since it's taking power from a big fat wire instead of the 75x relay. My question will be, is the post 30 has some fuse protection from the source already? I'm reluctant to add a fuse from the post 30 to the headlight relay pin 30 for simplicity sake. However, the power to the headlights are all fused at the fusebox. The issue is just for the short 12awg wire I installed from post 30 to the relay.

Thanks.

[richardodn]

Assuming I understand Audi's numbering conventions on the power distribution diagrams, any pin marked 30 is straight from the battery. You need a fuse.

[chris164935]

The wiring that goes from the relay to the headlights does not have a fuse on it already? Your simple wire from post 30 to the relay will not have power going to it when the relay is off; it doesn't need to be fused IF you already have a fuse somewhere between your relay and the headlights.

[maxiz1]

Thank you for your input. Yes there's already fuse going to the headlight. But coming from the post 30 to the relay input I guess I'll be better to put another one, just in case that section get shorted.

[walky_talky20]

Indeed, that would be a nice thing to do.

Audi skates by on the edge with their wiring, I have no idea how they get away with it. They have constant, completely un-fused battery power going all the way to things such as the ignition switch and the headlight switch. Yeah, you know those headlight switches that like to melt and fail whilst being forced to run the entire load of the parking lights, high beams and low beams (simultaneously)? Yeah. The fuses are totally after that thing. lol

[maxiz1]

Indeed, that would be a nice thing to do.

Audi skates by on the edge with their wiring, I have no idea how they get away with it. They have constant, completely un-fused battery power going all the way to things such as the ignition switch and the headlight switch. Yeah, you know those headlight switches that like to melt and fail whilst being forced to run the entire load of the parking lights, high beams and low beams (simultaneously)? Yeah. The fuses are totally after that thing. lol

Walky - sounds scary to me. Seems there's a lot of failure point for an old car that could cause it to burn down. Is it wise to put one big fuse at the positive terminal of the battery? If so, what would be the fuse rating?

[walky_talky20]

You'd want the starter and alternator directly connected, but for the wire that goes from battery into the cabin, you could probably fuse at 100 Amps.

[andyrew]

The large positive post from the battery should be going directly to the starter, which you should then have a thick wire going directly from the starter to the alternator. The screwed on post should be going to the fuse block and that is what you can put a fuse on.

Just figuring this out myself for my custom install..