Headlight Relay Setup..
10-17-2011, 12:34 AM
#1
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Headlight Relay Setup..
Started a project to pull current from the CE for the headlights, and build a relay harness.
Cant hurt, if done right, that'll be pulling out 160w of energy from the CE panel.
Initial testing showed, at warm idle, 13.28v at the jump post where I will be pulling current from for the harness/relays/etc.
On low beam, the drivers side sees 11.4v at the plug, light on. The pass side sees 11.04v at the plug, with the light on.
On low beam, the drivers side sees 10.7v at the plug, light on. The pass side sees 11.3v at the plug, with the light on.
As it is, im seeing up to a 15% drop in voltage from post to lights..as a comparison.
Cant hurt, if done right, that'll be pulling out 160w of energy from the CE panel.
Initial testing showed, at warm idle, 13.28v at the jump post where I will be pulling current from for the harness/relays/etc.
On low beam, the drivers side sees 11.4v at the plug, light on. The pass side sees 11.04v at the plug, with the light on.
On low beam, the drivers side sees 10.7v at the plug, light on. The pass side sees 11.3v at the plug, with the light on.
As it is, im seeing up to a 15% drop in voltage from post to lights..as a comparison.
10-17-2011, 11:15 AM
#3
Three Wheelin'
That's one of the 1st things I did when I got my 83. It had standard sealed beams and you couldn't see 10 feet on an unlighted road. I already had Hella H4 Ecode headlights on my 951 and when I added an Iceshark wiring harness, it really made a difference on that car. So, I decided to go the same route on the 928. On the 951, the power is pulled from the alternator, because that is the closest source on that car. I went this route on the 928, but according to Daniel Stern,http://www.danielsternlighting.com/home.html, I could have used any 'hot' terminal; so I could have flipped the harness over and used the Charging Post. I installed the relays behind the front closing panel. There is just enough room to clear the headlights. This puts everything right at the lights, so there is no voltage drop and the old headlight socket is there to give you switch power for the relays.
10-17-2011, 11:22 AM
#4
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Ya..im bored, so I'll build my own.
Going with 10g wire (its sitting around), and will wire a diode tween the low and high side, so that I get both beams on 'high', instead of cutting out the low.
Going with 10g wire (its sitting around), and will wire a diode tween the low and high side, so that I get both beams on 'high', instead of cutting out the low.
10-17-2011, 01:10 PM
#6
Chronic Tool Dropper
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Did you check the voltage at the 30 bus in the CE panel with lights on? Just curious what you found.
The cable from alternator to jump post is listed as 4ga but looks smaller. There are three smaller feeds from jump post to the CE panel, and that may be part of the voltage drop problem.
Take plenty of pictures of your installation, please.
The cable from alternator to jump post is listed as 4ga but looks smaller. There are three smaller feeds from jump post to the CE panel, and that may be part of the voltage drop problem.
Take plenty of pictures of your installation, please.
10-17-2011, 01:50 PM
#7
I am no electrician. I do usually know proper wiring when I see it, but that doesn't always happen.
It is my understanding that it may be a good idea to make the actual powering of a high-load unit, such as a light, a pump, or similar happen CLOSER to the object itself. Meaning, instead of running 12V with load for the powered object all over the car, you should have low-load wires going TO the location of the powered object and then draw current to it through a relay? I think its sort of like a BUSS system - run large wires to the back and front of the car (as are already there - either at the power post infront, or the battery at the back) and have short fat power to what you need to power coming through "di-pole" or whatever the are called relays.
Have I explained this properly? Am I right?
It is my understanding that it may be a good idea to make the actual powering of a high-load unit, such as a light, a pump, or similar happen CLOSER to the object itself. Meaning, instead of running 12V with load for the powered object all over the car, you should have low-load wires going TO the location of the powered object and then draw current to it through a relay? I think its sort of like a BUSS system - run large wires to the back and front of the car (as are already there - either at the power post infront, or the battery at the back) and have short fat power to what you need to power coming through "di-pole" or whatever the are called relays.
Have I explained this properly? Am I right?
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10-17-2011, 03:22 PM
#8
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Brendan - that is what he is doing.
I would not run both to the jump post - use that for the pass side - I'd fuse the master supply with a good large fuse at the jump post then local fuses per filament. since you have flexing wires at the headlight buckets - you really need a fuse before that point just in case.
For the drivers side you already have a hot post at the ABS unit (its more hidden but you can wire to it - it has an existing beefy feed from the Alt. then do the same as on the pass side...
Alan
I would not run both to the jump post - use that for the pass side - I'd fuse the master supply with a good large fuse at the jump post then local fuses per filament. since you have flexing wires at the headlight buckets - you really need a fuse before that point just in case.
For the drivers side you already have a hot post at the ABS unit (its more hidden but you can wire to it - it has an existing beefy feed from the Alt. then do the same as on the pass side...
Alan
10-17-2011, 03:35 PM
#9
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Alan:
I thought about using that..and I may still do that as both relays will be closer to that point. (At least in the initial installation). Just wasnt sure what I wanted to disturb, where.
If im happy with it all, and I will be...I will be investing in better hardware in a few places, to make it much more reliable for the LONG term.
I thought about using that..and I may still do that as both relays will be closer to that point. (At least in the initial installation). Just wasnt sure what I wanted to disturb, where.
If im happy with it all, and I will be...I will be investing in better hardware in a few places, to make it much more reliable for the LONG term.
10-17-2011, 05:34 PM
#10
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You say both relays - you will need 2 per side - right? one for high beam and one for low beam.
If you wire it appropriately you can use an SPST relay for the high beam and a SPDT relay for the low beam and then feed the high beam output to the 87a terminal of the SPDT for low beam. Use the 87 to battery supply and 30 to feed the low beam filament. This way you can have low & high on simultaneously in high beam with no diode. You can then also swap the SPDT relay for an SPST to revert to normal behaviour with no wiring change to make.
NB don't do this with uprated bulbs - the common ground inside the bulb capsule will not be rated for the higher current load and may well burn out - you will end up with no lights! - not good!
Alan
If you wire it appropriately you can use an SPST relay for the high beam and a SPDT relay for the low beam and then feed the high beam output to the 87a terminal of the SPDT for low beam. Use the 87 to battery supply and 30 to feed the low beam filament. This way you can have low & high on simultaneously in high beam with no diode. You can then also swap the SPDT relay for an SPST to revert to normal behaviour with no wiring change to make.
NB don't do this with uprated bulbs - the common ground inside the bulb capsule will not be rated for the higher current load and may well burn out - you will end up with no lights! - not good!
Alan
10-17-2011, 05:39 PM
#11
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....On low beam, the drivers side sees 11.4v at the plug, light on. The pass side sees 11.04v at the plug, with the light on.
On low beam, the drivers side sees 10.7v at the plug, light on. The pass side sees 11.3v at the plug, with the light on.
As it is, im seeing up to a 15% drop in voltage from post to lights..as a comparison.
On low beam, the drivers side sees 10.7v at the plug, light on. The pass side sees 11.3v at the plug, with the light on.
As it is, im seeing up to a 15% drop in voltage from post to lights..as a comparison.
The voltage drops you show are not otherwise unusual.
Note that the 15% less voltage relates to a much larger % of lost lumens!! this is not a linear relationship - not even close.
Now the extra brightness will also significantly reduce filament lifetime - thats the inevitable trade-off
Alan
10-17-2011, 07:09 PM
#12
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You say both relays - you will need 2 per side - right? one for high beam and one for low beam.
If you wire it appropriately you can use an SPST relay for the high beam and a SPDT relay for the low beam and then feed the high beam output to the 87a terminal of the SPDT for low beam. Use the 87 to battery supply and 30 to feed the low beam filament. This way you can have low & high on simultaneously in high beam with no diode. You can then also swap the SPDT relay for an SPST to revert to normal behaviour with no wiring change to make.
NB don't do this with uprated bulbs - the common ground inside the bulb capsule will not be rated for the higher current load and may well burn out - you will end up with no lights! - not good!
Alan
If you wire it appropriately you can use an SPST relay for the high beam and a SPDT relay for the low beam and then feed the high beam output to the 87a terminal of the SPDT for low beam. Use the 87 to battery supply and 30 to feed the low beam filament. This way you can have low & high on simultaneously in high beam with no diode. You can then also swap the SPDT relay for an SPST to revert to normal behaviour with no wiring change to make.
NB don't do this with uprated bulbs - the common ground inside the bulb capsule will not be rated for the higher current load and may well burn out - you will end up with no lights! - not good!
Alan
And..to be clear..
30 is battery hot
87 (and 87a if dual pole output) are switched hot to lights
86 is trigger, 85 is ground from trigger.
I dont think I should feed the low-beam trigger from the high beam trigger without a diode, because of the implications of feeding voltage into that system/bus backwards and inducing other neat electrical issues.
10-17-2011, 07:35 PM
#13
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Porsche has dual L/R feeds with each filament seperately fused all the way from the headlight to relay - this is safety issue - if you blow a fuse or lose a connection - you only lose one side. You should keep this.
So I'd replicate this - dual relays for each side - plus you get the least voltage drop and the shortest/simplest wiring if the relays are near the bulbs - I'd actually put the relays and fuses in each headlight bucket. Quick & easy to access - but agreed quite tough to fit in. However it is the best solution I think - all you need is a new power & ground up to the bucket.
I did mean exactly what I wrote on the config - but re-read it - you didn't get it.... think it through.
Normal relay convention is indeed power to 30 - but its really just a general convention. If you need to use the switch contacts as a power selection device operating it in reverse is common practice - and there is no down side.
87a is most commonly the NC connection not a second output contact - someone screwed up by also using that terminology - such relays are not very common. Use the generic Bosch style SPDT versions (NO=87 & NC=87a)
This way you need no additonal components (diode) and the only thing the existing headlight wires feed are the relay coils. All the filament side wiring is on the output contact side of the relays. Bosch style SPST & SPDT relays are commonly available at equivalent (and low) costs.
Alan
So I'd replicate this - dual relays for each side - plus you get the least voltage drop and the shortest/simplest wiring if the relays are near the bulbs - I'd actually put the relays and fuses in each headlight bucket. Quick & easy to access - but agreed quite tough to fit in. However it is the best solution I think - all you need is a new power & ground up to the bucket.
I did mean exactly what I wrote on the config - but re-read it - you didn't get it.... think it through.
Normal relay convention is indeed power to 30 - but its really just a general convention. If you need to use the switch contacts as a power selection device operating it in reverse is common practice - and there is no down side.
87a is most commonly the NC connection not a second output contact - someone screwed up by also using that terminology - such relays are not very common. Use the generic Bosch style SPDT versions (NO=87 & NC=87a)
This way you need no additonal components (diode) and the only thing the existing headlight wires feed are the relay coils. All the filament side wiring is on the output contact side of the relays. Bosch style SPST & SPDT relays are commonly available at equivalent (and low) costs.
Alan
Last edited by Alan; 10-17-2011 at 07:50 PM.
10-19-2011, 01:27 AM
#14
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Alan:
I just did the drivers side tonight in my original manner, but two relays in the headlight bucket, and a single 10ga power feed and ground from the ABS feed.
Very nice.
Only dropping .1v from that main connection to the bulb with the lights on.
Intensely stupid bright.
And I launched this, because the PO put in 80/100 bulbs, and didnt like that load thru the old OEM system.
Its WHITE as all hell now.
I will go back in, and re-config to run as you say..just didnt quite get it, unless youre simply adding a trigger to the low beam relay from the high beam output.
?
I just did the drivers side tonight in my original manner, but two relays in the headlight bucket, and a single 10ga power feed and ground from the ABS feed.
Very nice.
Only dropping .1v from that main connection to the bulb with the lights on.
Intensely stupid bright.
And I launched this, because the PO put in 80/100 bulbs, and didnt like that load thru the old OEM system.
Its WHITE as all hell now.
I will go back in, and re-config to run as you say..just didnt quite get it, unless youre simply adding a trigger to the low beam relay from the high beam output.
?
10-19-2011, 01:30 PM
#15
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OK good.
Let me restate for clarity.
Each relay coil is fed only by the existing headlight connections
So for each side:
Coils:
====
High beam relay coil is fed on terminal 86 from the stock high beam wire, w/ terminal 85 grounded
Low beam relay coil is fed on terminal 86 from the stock low beam wire, w/ terminal 85 grounded
Relay Switched Terminals: (NO = Normally Open Circuit, NC = Normally Closed Circuit, [Normally = non-energized coil])
================
High beam relay terminal 30 is battery+, terminal 87 (NO) feeds the high beam bulb filament
>>> High beam relay terminal 87 ALSO feeds the low beam relay terminal 87a (NC) <<<
Low beam relay terminal 87 (NO) is battery+, terminal 30 (common) feeds the low beam bulb filament
So note that in high beam mode the high beam relay connects terminal 30 to 87 and feeds the high beam filament and also feeds through the nomally closed (NC) contacts of the non-energized low beam relay to terminal 30 and on to the low beam filament.
Hope that is clearer
Alan
Let me restate for clarity.
Each relay coil is fed only by the existing headlight connections
So for each side:
Coils:
====
High beam relay coil is fed on terminal 86 from the stock high beam wire, w/ terminal 85 grounded
Low beam relay coil is fed on terminal 86 from the stock low beam wire, w/ terminal 85 grounded
Relay Switched Terminals: (NO = Normally Open Circuit, NC = Normally Closed Circuit, [Normally = non-energized coil])
================
High beam relay terminal 30 is battery+, terminal 87 (NO) feeds the high beam bulb filament
>>> High beam relay terminal 87 ALSO feeds the low beam relay terminal 87a (NC) <<<
Low beam relay terminal 87 (NO) is battery+, terminal 30 (common) feeds the low beam bulb filament
So note that in high beam mode the high beam relay connects terminal 30 to 87 and feeds the high beam filament and also feeds through the nomally closed (NC) contacts of the non-energized low beam relay to terminal 30 and on to the low beam filament.
Hope that is clearer
Alan