[WA-Alfa]

1974 105 GTV 2000 RHD

I am in the process of installing an engine fan, condesnor fan and I thought that I might as well install relays for the headlights was well. Where is the best place to draw current for these? I could draw it from the +ve battery lead connected to the starter motor or I could connect it to the alternator itself.

Does anyone have any guidence as to the most appropriate place to tap into my car's power supply?

 

[Alfajay]

Really, either of your two choices would work OK. There are large gauge wires connecting the battery "+" to the alternator, so both points are electrically the same (unless your car has an ammeter).

I always use the alternator output lug for this purpose. My reasons are:

1) It looks cluttered to have a bunch of 10 ga wires attached to the battery "+" lead
2) 99.9% of the time when the headlights and/or engine fan are one, the engine is going to be running. Might as well draw the current directly from the source.
3) If you do have an ammeter, you want it to measure current in & out of the battery - in that case, heavy loads like headlights should come off the alternator so as not to interfere with the ammeter reading.

Don't forget to put fuses in the circuit from the alternator to the relays.

 

[kpas]

Howdy!

I run my headlight relays from the +ve terminal, and have them heat shrinked to the original wire with red heat shrink to keep it all looking tidy.

 

[BobK]

why would one headlight work, and the other not? are they on seperate lines?

1992 spider

 

[papajam]

are they on seperate lines?

Yes. There are 4 fuses for the headlights; one fuse each for L & R high & low beams (fuses 11-14).

 

[BobK]

thanks that helps