Charger1970's world famous headlight relay upgrade

[b5blue]

    I thought one of the cons to placing them under the kick panel or dash was that your still running the currant threw the bulkhead connector....

That is spot on! and pretty much makes up my mind...thanks guys!


Oh, one more question, it just dawned on me. Does power running though the AMP guage power EVERYTHING except the starter??? (headlights, Fan, wipers ect) If so that's a messed up design!

The amp gauge only "sees" battery recharge/supply volts/amps pass through it. - for drawing off battery, like cranking, + for recharging battery. Other then that a reaction bip on the gauge as the alt output compensates for a new load just as it's turned on.

[AKcharger]

'72 Charger complete, one to go!

Lessons learned:
- Used the dual relay plug from parts-express WARNING...took 3 weeks to recieve parts and that's after it was processed, they appearently use some fly by night shipper, if you use them plan WAAAAY ahead. Anyway, the wires seemed random so I depinned it and matched the wires  (red to pos, black to neg ect.)

- Placed relays under Battery tray

- Works great, '70 is next!

[johnnycharger]

 

[AKcharger]

'70 is done now too, it is a much more noticable improvement than the '72, maybe the wires are older?

[cougs]

This topic has been around for a long time but I don't see pics or a discussion on how people ran the wire from the alternator back to under the battery.  Is there another place to tap into for power other than the pos+ on the alternator?

[b5blue]

That Alt. output is by far the best as a stand alone feed to the lights, you add no load to any other wiring, in fact you reduce load through the dash. (A good thing!)   

[cougs]

Could you tie-in at the solenoid so you don't have to run a new wire clear from the ALT?

[Dino]

This topic has been around for a long time but I don't see pics or a discussion on how people ran the wire from the alternator back to under the battery.  Is there another place to tap into for power other than the pos+ on the alternator?

The alternator is real close to the passenger side frame rail so why not run the wire over the rail and into the front radiator support frame?  You can hide it there easily and run the wire to the battery.  Unless you point it out, nobody will notice.

[cougs]

There is a small wire coming off the positive side of the battery (maybe 12 ga) that s built into the terminal.  It there a reason you can't tap into that?

[70 Charger RT]

Interesting read guys.  Especially the part about feeding accessories and headlights from the alt and NOT the battery.  When I do my upgrade, I will be using circuit breakers like previously mentioned.  At least with a CB your lights will cycle in case of a short circuit.  A fuse will leave you in the dark if it blows (yes you are reducing your chances of it blowing by having two fuses).  I will also be keeping the relays AS CLOSE AS POSSIBLE to the alternator.  The whole idea here is to minimize voltage drop.  I'll probably stick the relays under the batt tray.  Having the relays in the car is good for protection but IMHO increases voltage drop and therefore having dimmer headlights.  Yes, many of you can live with a small voltage drop by having your relays inside the car. 

[squeakfinder]

   10 gauge wire from the starter post to one of those GM junction blocks that I mounted next to the battery.

[squeakfinder]

     I did tie the pigtail from the battery clamp to the junction block. But, it's just redundancy. I figured it couldn't hurt. Allthough I would not rely on the pigtail because of the corrosion issue's that occur at the positive post.

[Kern Dog]

I tried the relay "upgrade" on my 70 Charger and it screwed everything up.
The headlight doors on the 70 are electric, and with the relays only serving the headlights, the action of the doors was tricky. They wouls ONLY close with high beams on. They would only OPEN with the high beams on.
I Just called it quits and installed an Evans wiring harness. NEW wire without relays is better than old wiring without relays.

[charger Downunder]

I tried the relay "upgrade" on my 70 Charger and it screwed everything up.
The headlight doors on the 70 are electric, and with the relays only serving the headlights, the action of the doors was tricky. They wouls ONLY close with high beams on. They would only OPEN with the high beams on.
I Just called it quits and installed an Evans wiring harness. NEW wire without relays is better than old wiring without relays.

You need to read this thread and do the head lamp motor relay upgrade at the same time.
http://www.dodgecharger.com/forum/index.php/topic,8077.0.html

[MaximRecoil]

Where does the voltage regulator fit into this schematic?
An un-regulated alt can put out 15+ volts, what does this do to the life of a 12V bulb??

Also, doesn't that high of a un-regulated voltage going to the battery cause problems?

Thanks

I don't believe this question was ever actually answered, and I'm wondering about it myself. The "headlight relay upgrade" which is the subject of this thread would feed the headlights with unregulated voltage directly off the alternator, because the path becomes alternator > relay > headlights > ground ... no voltage regulator in that circuit at all. So, will the 15+ volts direct from the alternator cause the headlights to prematurely blow out, and/or to be brighter than they are designed to be?

[Ghoste]

It's fused, wouldn't that prevent an overcurrent?

[Dino]

Aren't the relays themselves limiting the output to 12v?   

[Pete in NH]

The voltage regulator, in a properly working electrical system, keeps the alternator output between 13.8 and about 14.4 volts. This is the voltage applied to the headlights with this relay upgrade whether you take the voltage off the battery or alternator. It should be taken off the alternator side of the ammeter or the ammeter will read the highlight current as battery charging current.

What this relay upgrade does is eliminate all the voltage drops through the headlight switch, wiring and bulk head connector pins,so the lights are brighter. But, brighter also means the filament of the lamp is operating at a higher temperature and all things being equal will burn out sooner.

[Ghoste]

It would also eliminate a large current flow through the ammeter, no?

[Dino]

Any way to keep it at a steady 12v or close instead of going up to 14?

[Pete in NH]

On the current flow through the ammeter with this upgrade its a yes and no. If the engine and alternator is turning fast enough the energy for the headlights will come out of the alternator and not go through the ammeter. At engine idle it will likely come out of the battery and through the ammeter. What the upgrade does do is keep some current out of the bulkhead connector pins. This modification and the fleet bypass wiring mods are good ones to make for the sake of the connector pins.

Unfortunately, finding  a way to keep the voltage at the headlights at 12 volts would kind of defeat the purpose of this upgrade as you would not have brighter lights which along with the taking some of the strain off the wiring is the end goal. I did a little research and General Electric rates their headlights at 13 volts kind of mid way between battery voltage and charging system voltage. So, I think all in all, headlight life would not suffer all that much and you get brighter lights and do some good things for the bulk head connector.

[Dino]

On the current flow through the ammeter with this upgrade its a yes and no. If the engine and alternator is turning fast enough the energy for the headlights will come out of the alternator and not go through the ammeter. At engine idle it will likely come out of the battery and through the ammeter. What the upgrade does do is keep some current out of the bulkhead connector pins. This modification and the fleet bypass wiring mods are good ones to make for the sake of the connector pins.

Unfortunately, finding  a way to keep the voltage at the headlights at 12 volts would kind of defeat the purpose of this upgrade as you would not have brighter lights which along with the taking some of the strain off the wiring is the end goal. I did a little research and General Electric rates their headlights at 13 volts kind of mid way between battery voltage and charging system voltage. So, I think all in all, headlight life would not suffer all that much and you get brighter lights and do some good things for the bulk head connector.

Sounds like a win-win to me!  I'm doing this mod when I do the power window and door upgrade, now all I have to do is find that alternator that's out of stock...

[MaximRecoil]

The lowbeam headlights, the ones with three prongs, they have two filaments, one lights for low beams and the other lights for high beams, right? One of the prongs is hot for one filament, the other is hot for the other filament, and the third (center) prong is common ground for both of them, correct?

If I'm understanding this correctly, when your low beams are on, a single filament (let's call it filament A) in each of your two outer headlights is lit, and when your high beams are on, each filament A shuts off and each filament B comes on in your two outer (3-prong low beam) headlights. Additionally, the two inner (2 prong, single filament, high beam) headlights come on as supplementary lights.

When your low beams are on, a hot wire (let's call it hot wire X) is in parallel with two filaments (filaments A), one in each outer headlight. When your high beams are on, a different hot wire (hot wire Y) is in parallel with 4 filaments, two filaments B for the outer headlights, and each of the single filaments in the inner headlights.

After doing the relay upgrade:

- The #87 terminal of relay #1 would connect to hot wire X, and the #87 terminal of relay #2 would connect to hot wire Y.

- The low beam wire from the dimmer switch (formerly part of hot wire X, but now cut) would connect to terminal #86 of relay #1, and the high beam wire from the dimmer switch (formerly part of hot wire Y, but now cut) would connect to terminal #86 of relay #2.

- The #85 terminal of both relays would be grounded to the chassis.

- The #30 terminal of both relays would connect to the alternator stud via heavy wire (10 AWG), each wire having an inline 30 amp fuse or circuit breaker.

Is that all correct? I'm trying to get a mental picture of how to wire up this relay upgrade.

[A383Wing]

If I remember, the center prong on the headlights is not ground, the ground for both filaments is one of the outside terminals

[MaximRecoil]

If I remember, the center prong on the headlights is not ground, the ground for both filaments is one of the outside terminals

Yes, you're right. I looked at it today and the black wire that grounds to the radiator chair is connected to one of the side terminals on the low beam headlight.

Are the existing factory hot and ground wires that run to the headlights sufficient to be spliced into for this upgrade, or should heavier wires be run all the way from the outputs of the relays to the headlight plugs, and from the plugs to ground? Those two factory ground wires that screw onto the radiator chair on either side of the car only appear to be 18 gauge. The hot wires (I believe red for the high beams and blue [or purple] with a white stripe for the low beams) appear to be 16 gauge.