Headlight Relay Conversion

codekiddie said:
For some time I had wanted to use relays for switching the dipped and main beam headlights, and last weekend I finally got around to it :)

The first thing to do is disconnect the battery. Fortunately I had previously fitted a quick-disconnect which made this job very simple :D

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Just found this excellent write-up after a search on "headlight relay" but unfortunately the images aren't showing. Any chance of an update? Thanks codekiddie!
 
I can't claim any credit for the photos suddenly appearing, but I did have the same problem when I visited the page a minute ago. The photos are hosted on my web space, and they are correctly referenced on the forum pages so should be fine.

Nice to see the page is still useful for everyone.
 
I could not see the photo's, but they appear if you use the link in post #15 of this thread.

Excellent write up.
 
Great ideas here. Would not have thought to solder wiring to fuse connectors, might try that when I do this. Can you explain the use of 5 fuses on each side please?
Hard to reconcile the lack of relays with experience of a Porsche 928 with upwards of 20, as well as 30+ fuses.
Another idea from the 928 - it also has a boot mounted battery, under a flat mounted spare wheel, making a jump start a bit of a struggle. They solved this with a hot point mounted in the engine bay, with big enough wiring to allow for a jump start, as well as feeding other needs in the engine bay. The hard plastic base is screwed to the body, and allows for connections via eyelets under an M6 screw in post , with a hex section big enough to take a jumper lead clamp. It is protected from accidental shorts by a screw on plastic hood. I am thinking of fitting one of these fed from the ammeter shunt on the offside of the engine bay, and another on the near side connected directly to the starter solenoid for jump starting . Here is a pic with the protective cover unscrewed.
ayCfkxM.jpg
 
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Good idea, in principle, but I doubt the wiring from the shunt will take the current to start the car. I’d take a feed either from the stud in the driver’s footwell or preferably from the main 12v feed on the starter motor. The cable needs to be the same gauge as the main battery cable. Also, bear in mind you run extra risk of things shorting out if the cable comes loose or gets trapped, as this cable will be unfused.
 
Was only going to tap off the shunt for headlight relays, electric fan etc, nothing big. Jump start post would come off the starter connection.
 
Hi, For a jump start facility you could wire in an Anderson connecter, or the Australian equivalent, and modify your jump leads to suit. That would be inherently much safer, you could even put one each end of the vehicle to cover any eventualities.

Colin
 
Seen what happens when an idiot shorts an Anderson socket? If I modify my jump leads to Anderson then they are useless for anything else. Maybe an adaptor from clamps to Anderson?
 
A rather large 'bump' on this thread. I have a vague understanding of the workings of a relay. I'm wondering if installing a relay for the lights decreases the current that is put through the fuse box. Or is it easy to remove the current alltogether and install a relay with a fuse in it?

My headlights are giving intermittent problems and the (new!) fusebox is getting very hot on the LH side light fuse.
 
A relay will reduce the current through the std fuse to very small, and safe levels. You will need to provide a high current supply line for the relay to switch on - can be off the starter relay or the alternator battery connection, but the current will not show on the ammeter. Another source is to splice into the heavy wire from ignition to the light switch - behind the switch panel.

Edit- a relay with a fuse is still a good idea, as you still need to protect the high current supply from overload. I have a 40A resettable breaker on the line that supplies all my lights.
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There are relays with attached fuses-
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Sorry to bring up an old thread, but I’m looking to fit some relays to my headlights im just wondering what gauge cable did you use for the relay wiring and the feed from the alternator ?
Would 14awg be ok for the relay wiring and I’m guessing 6/4awg for the feed wire?
Thanks Josh
 
6 AWG (4.11mm in U.K.) should be/is plenty for both dip and main beam load and 14awg -2mm -for the relay trigger (coil) is also plenty.

Dave
 
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colnerov said:
Hi, For a jump start facility you could wire in an Anderson connecter, or the Australian equivalent, and modify your jump leads to suit. That would be inherently much safer, you could even put one each end of the vehicle to cover any eventualities.

Colin
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I've done just that with Anderson connector and made up some bespoke leads with an anderson coupling in it so I can use either clips or plug in. Anderson plug sits above battery in boot so I can just plug the lead in without unpacking anything...
 
have just added relays and new lamp units to our 3500s 5spd with odd glow worms on dip on the wrong lamps found the back feed was due to the common melted fuse box so dash out and replacement blade and side entry lucar box in the post £18 apart from removing the dash to get vari focal vision access this will be a cheap fuse box replacement apart from two shreaded wheat to crimp all the new lucars
pete
 
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