Charger1970's world famous headlight relay upgrade

[A383Wing]

the stock wires should be efficient enough

many have done this upgrade and not had to replace factory wires

[MaximRecoil]

It wouldn't make any difference, electrically speaking, whether you run the power wires to the relays' #30 terminals from the battery or the alternator post, especially in my car where I have already added an 8 gauge wire (with 12 gauge fusible link) from the alternator post to the starter relay, and from the factory there is already an 8 gauge wire from the starter relay to the positive terminal on the battery. This effectively creates a single 8 gauge wire going from the alternator to the battery. So whether you tap in at the alternator post, starter relay post, the positive battery terminal, or any other place along the 8 gauge wire path, it makes no difference (aside from minuscule and insignificant differences in resistance).

Since the battery is much closer to where I'll be mounting the relays and circuit breakers than the alternator is, that's where I'm going to tap in.

[MaximRecoil]

I think I'm going to use just one self-resetting circuit breaker, even though I ordered two. If I were using fuses, I'd definitely use two (one for each relay), so that if a fuse blows, I could step on the dimmer switch and have lights again (though in some cases that wouldn't be a good idea, i.e., if the low beam fuse blew and you had to switch to high beams, and there was oncoming traffic, it would be dangerous to continue driving like that).

With a self-resetting circuit breaker, it would reset in a couple/few seconds anyway (the factory stock headlight wiring only has one self-resetting circuit breaker too). Plus, if possible, I'd pull over and fix the problem anyway if the breaker started tripping (I'll keep the extra circuit breaker I ordered in the car, along with some spare relays).

[Pete in NH]

Keep in mind if you are still using the dash ammeter if you pull the headlight current off the battery side of things the headlight current will display as battery charge current. That's why connecting the headlight circuits to the alternator post might be a better place.

[MaximRecoil]

Keep in mind if you are still using the dash ammeter if you pull the headlight current off the battery side of things the headlight current will display as battery charge current. That's why connecting the headlight circuits to the alternator post might be a better place.

My ammeter works, but it is bypassed for the sake of reliability. The fact that I have a shunt wire (8 gauge) going directly from the alternator to the starter relay already renders the ammeter inaccurate anyway, even if it were hooked up, because most of the battery charging current will take the path of least resistance (the 8 gauge path from the alternator to the battery, which doesn't include the ammeter).

[Pete in NH]

Yes, I had seen that the ammeter was bypassed in an earlier post but, I thought I would mention the connection side issue for those folks still using the ammeter.

[MaximRecoil]

A couple of weeks ago I was driving home from Skowhegan (about an hour's drive) at night, and just before I got to my town line the headlights went out. A few seconds later they came back on, then they went out again, and so on. It did this several times, and then they stayed on long enough to get home (they did it one more time just before I pulled into my driveway). When I parked in my driveway and turned off the lights, I noticed the headlight switch was hot. It was the first time I'd ever taken this car for a long drive at night, and it was also the first time the headlights had done that since I started driving it on the road in 2011.

My mechanic friend said it was the circuit breaker in the headlight switch. I didn't even know there was a circuit breaker in the switch, but it made sense that it would get hot enough to trip a circuit breaker considering the long run of thin wire that goes through a bulkhead connector, and has the added load of halogen headlights rather than the standard headlights that the circuit was designed for.

So a search brought me to this thread, and it looked to be just the thing. My headlights are now much brighter (I'm getting 13.2 VDC to the high beams at idle, which is perfect), and the headlight switch never gets hot. Even in daylight they look almost white rather than pale yellow like they used to look in the day:

[A383Wing]

yup...those relays make a big difference...and saves yer wiring also

Bryan

[flyinlow]

I have done this on both Chargers big difference. Only thing I did different was use 4 relays and 4 fuses. One for each low beam, one for the outboard high beams and one for the inboard high beams. A little more wiring ,but no single failure puts you in the dark. There is always two independent circuits powering headlights.  

[A383Wing]

I had to use 4 relays for my 66 Charger, but for a different reason. One for low beam, one for high beam, one for headlight motor rotate up, one for rotate down.

Bryan

[cjw916]

Thanks for a great thread!

I upgraded to H4 halogens and had been experiencing over-heating of the switch when I leave my high beams on for a long time (5 minutes?), so, this relay upgrade is the fix I've been looking for!

http://www.dodgecharger.com/forum/index.php/topic,104078.0/all.html

Only thing I noticed, was the link to waytekwire.co no longer links to a Bosch 75101, so I ordered the Bosch 75401 relays instead.

Also, waytekwire makes you order a minimum of some of the connectors, etc?
I had to order 10 of the relay mounting blocks: 75280, they were cheap, though. $6.79 for 10
I had to order 50 of the relay connectors: 31073, they were very cheap, too. $8.27 for 50
It let me order only 2 of the 5-pin relays. $13.70 for 2
Grand total $33.76 to ensure my 45 year old wiring does not burn my car down! LOL.

If anyone needs 2 mounting blocks or connectors, shoot me a PM, I'll send you a couple, I have extras. LOL.

Christopher

[elacruze]

I've been tracking this since my resto, got pointed to Daniel Stern; Lighting expert.

There's WAY too much information on his website for me to quote any here, you really need to read it. I'll post copy from our emails.

"...First, decide how well you want to see at night and how much money you want to spend doing it. This should be decided based on how much nighttime driving you do and at what kinds of speeds, and/or on your personal preference for how important it is to you to have highly effective, well-focused headlamps. H4s are the standard upgrade, and are not advisable if you are planning on doing much night driving. H4 lamps (of any manufacture) in the 5.75" round size are not very efficient, because with H4 (any H4 bulb in any H4 lamp), only 55% of the total reflector and lens area is used to collect and direct the light for the low beam, because of the low beam filament shield inside the H4 bulb. That's OK if you have a large lamp, but with small lamps like the 5.75" rounds, you really can't collect much light from the bulb. But if you don't do much night driving and want to keep the cost down, a quality pair of H4 lamps (Cibies are the ones to get, $79/ea) will still give a broader beam coverage than the sealed beams.

If you do much of any night driving, instead of H4s, put in the Hella BiFocal H1 low beams ($123/ea), which were co-developed by Hella and BMW. They are the most efficient, best focused replaceable-bulb halogen headlamps in this size format, and I stock the commercial-duty version with toughened hardglass lenses. Use them in conjunction with parabolic H1 high beams ($79/ea). Use Narva Rangepower+50 H1 bulbs all around ($15.59). These will give vastly better performance than the sealed-beam junk _and_ vastly better performance than any H4 conversion (much more efficient optics; entire optical area used to form the low beam). Illumination is broad, long-reaching, and very well focused, with no upward stray light and significantly less glare to oncoming drivers (because the light is focused where you need it) -- a substantial upgrade from the sealed beam lamps' dim, narrow tunnel of light with no side spread and excessive upward throw that causes backglare in bad weather, and likewise a substantial upgrade from the H4 lamps' relatively meager beam performance."

http://www.danielsternlighting.com/home.html

[ChargerKen]

Something to keep in mind when doing this upgrade. If you do this upgrade inside the car all of that headlamp current still has to flow through two spade terminals in the bulkhead connector. Doing this underhood straight from the alternator reduces the load on these two terminals, and circuit, reduces the resistance to the headlamps. These cars with ammeters are actually prone to ammeter circuit overload. 70s Dodge pickups (which are very similar wiring circuits) are notorious for melting the ammeter. Anything you can do to reduce the load off of this circuit is great. My .02 cents.

[squeakfinder]

Something to keep in mind when doing this upgrade. If you do this upgrade inside the car all of that headlamp current still has to flow through two spade terminals in the bulkhead connector. Doing this underhood straight from the alternator reduces the load on these two terminals, and circuit, reduces the resistance to the headlamps. These cars with ammeters are actually prone to ammeter circuit overload. 70s Dodge pickups (which are very similar wiring circuits) are notorious for melting the ammeter. Anything you can do to reduce the load off of this circuit is great. My .02 cents.

This thread is getting to be a long read isn't it. I agree eliminating the bulkhead connector is probably the most important thing to do. I mentioned this on page 5 post #119.

[ChargerKen]

I'm sorry. I guess I didn't read through this as thouroughly as I thought I did.

[cjw916]

I finally got my relays installed.

[cjw916]

I finally got my relays installed. I used two 30Amp thermal fuses, then one relay for low beams (LH yellow leads), one relay for high beams (RH red leads). Since I mounted mine under my battery tray, where the vacuum can is supposed to go, I just ran a 10gauge (30Amp wire) Red hot and 10gauge Black ground directly off the battery. I know, if I ran the hot all the way to the alternator positive it would bypass my Amp meter. I wasn't that concerned with that.

The signal wires come form the left, I used male blades to insert in original female blade leads, so I didn't hafta cut any wires, just taped everything up after making connections. Used female blades out to lamp leads that head out toward right.

Can't see anything with the battery installed. :-)

Must've done it correctly? Everything works!

[A383Wing]

get rid of those cheese-ball style quickie fix-it battery post cable ends....you will be happier in the long run

[cjw916]

Geez. My pro wrench friend said the same thing. LOLz. We're putting in a new clutch after rebuilding my 4-speed, and he says, 'Get a new Mopar battery & proper battery cables, would ya?' Like I told him, I only spend money on her that makes her faster (or handle better, or prettier, or shinier, or etc etc). :-)

'Proper' batt cables ARE in my future. I've been lazy to measure. My starter cable crimp-on end @ the starter is my biggest motivator. Put a new MSD starter in her & that cable looked 'suspect'. :-)

[cjw916]

Also, waytekwire makes you order a minimum of some of the connectors, etc?
I had to order 10 of the relay mounting blocks: 75280, they were cheap, though. $6.79 for 10
I had to order 50 of the relay connectors: 31073, they were very cheap, too. $8.27 for 50
It let me order only 2 of the 5-pin relays. $13.70 for 2
Grand total $33.76 to ensure my 45 year old wiring does not burn my car down! LOL.

If anyone needs 2 mounting blocks or connectors, shoot me a PM, I'll send you a couple, I have extras. LOL.

Christopher

[cjw916]

get rid of those cheese-ball style quickie fix-it battery post cable ends....you will be happier in the long run

Have you got a link to anyone that sells reasonably priced replacements? I almost fell over when Year One had just the positive cable for $269!

[cjw916]

OK, drove to work last night and got to see what kind of amps the H4 headlights draw!

WOW!

Made me decide to run that hot wire over to the alternator post, after all! ! !

Parking lamps on, ammeter read about 9 Amps.

Dim headlights on ammeter read about 22 Amps!

Bright headlights on and the ammeter read about 36 Amps! ! !

Rather than burn my car to the ground, today I ran the hot over to the alternator post, and with the headlights on bright, ammeter was @ about 8 Amps. :-)

H4 lamps on bright draw almost 5 Amps per bulb! Glad I used 10 gauge wire (good for 30 Amps)! ! !

[MaximRecoil]

get rid of those cheese-ball style quickie fix-it battery post cable ends....you will be happier in the long run

Have you got a link to anyone that sells reasonably priced replacements? I almost fell over when Year One had just the positive cable for $269!

Unless you're concerned about a factory-correct appearance, make your own (or have them made at your local autoparts store if you don't have a tool for crimping large terminals). They will be better than the factory-original cables, and won't cost anywhere near hundreds of dollars (which is utterly absurd; another of many examples of arbitrarily high pricing in the "restoration parts" industry).

For the ultimate battery cables, use at least 2 gauge wire (1/0 or even 2/0 gauge is better; anything bigger than that is pretty well past the point of diminishing returns, and could be awkward/difficult to install, especially if it doesn't have a high strand count to make it flexible), tin-plated solid copper crimp-on battery terminals (like so - link), tin-plated copper crimp-on cable lugs (AKA: ring terminals), and some heat-shrink tubing (ideally 3M dual-wall adhesive-lined). 

[cjw916]

Thanks Recoil, I was checking out that cable website you pointed me to. Nice stuff. I am definitely going to order cables, terminals, lugs, solder slugs & shrink tubing from them. It will be a nice upgrade. :-)

http://www.wiringproducts.com

[Dino]

This is where I get all my wiring:
https://gregsmarinewiresupply.com/Zen/

Go to custom wires on that page to make them exactly how you want them.  I ordered battery cables, 6 gauge wires to run to alt and battery and fuse and several more finished cables in the 8 and 10 gauge range.  The total shipped was around $80 if I recall.  Awesome quality.