Gerald Morris
Senior Member
Greetings C-body Moparians,
Since the wiring is done on my headlight upgrade, I can start sharing my experience with folks. I'm happy to report this worked better than I expected, and if done well, this WILL significantly improve headlight luminosity and decrease the voltage drop imposed from running them.
1. Materials: This is the most decisive set of choices to make. Having examined a good number of pre-fab headlight relay conversion harnesses, I noticed that NONE of them use #10 AWG from power source all the way through to the headlight. Since any constriction in ampacity limits the entire circuit, this MUST BE AVOIDED if good cost effect is the goal. It is with me, always.
So I made my own harness, exclusively with good U.S.A. made #10 AWG primary wire, finely stranded for audio power which I bought from an eBay vendor. This really is the BEST #10 stranded I've ever handled, in 35+ years since my electrician's apprenticeship. An auspicious beginning.... I chose red for high beams, black for low and white for ground, just as Chrysler (or FoMoCo, who actually made the original, 53 yr old harness.) did. Best to be consistent in wiring conventions when adding new circuit elements to an old system.
The original headlight connectors have become quite brittle with age, as I found when replacing a low beam bulb a couple years ago with a junkyard buy. Be this as it was, I opted to keep them and just plugged a couple male slide connectors into the driver side low beam connector, nearest the battery where my relays
were to be placed. While the cheap sino-relay that came with my pusher-fan had a pre-fab harness wired
with #14 AWG wire, I purchased GOOD TYCO-BOSCH relays, made in Portugal for this job. I could find
NO relay connectors pre-wired in #10 gauge, which compelled me to just use 1/4 inch female slide
connectors.
The 4 circuit glass fuse holder from Dorman (Rock Auto purchase) worked perfectly for my design. I had already used two circuits for the cooler fan, leaving 2 spaces for the high and low beams. I use ONLY GLASS FUSES in Mathilda, and preferably Society of Fuse Engineers (SFE) certified ones.
Again, I'm blessed with some acquired from a deceased old duffer who hoarded treasures like these. Pity modern plastic fuses aren't tested or designed with the same old school rigor these were.
I fed the power supply side of my 2 30A fuses with a bit of #8 AWG wire, again meant to power audio amps and very finely stranded for maximum conductivity, straight from the top post terminal on the battery to the fuseholder, using a split brass bolt "kerney" to attach 2 short pieces of #10 to the two spaces on the
fuseholder and to the kerney. I use the same device for each of my two critical power connections, from
the alternator to the battery, then from battery to starter relay terminal post. The two 6 inch #12 AWG fusible links each attach to a kearney binding them to the #8 feeding the rest of the circuit. I might use a fusible link for the headlight feeds if I deem it likely that they might ever short. I HATE sacrificing ampacity for safety in such a setup, and the fuses DO protect everything below them. I might get a 10 gauge link instead if I lose sleep over this.
I have to stop this installment of my article here for now, having reached the limit on uploadable graphics. My server/workstation has also thrown an exception and needs a reboot.
To Be Continued.....
Since the wiring is done on my headlight upgrade, I can start sharing my experience with folks. I'm happy to report this worked better than I expected, and if done well, this WILL significantly improve headlight luminosity and decrease the voltage drop imposed from running them.
1. Materials: This is the most decisive set of choices to make. Having examined a good number of pre-fab headlight relay conversion harnesses, I noticed that NONE of them use #10 AWG from power source all the way through to the headlight. Since any constriction in ampacity limits the entire circuit, this MUST BE AVOIDED if good cost effect is the goal. It is with me, always.
So I made my own harness, exclusively with good U.S.A. made #10 AWG primary wire, finely stranded for audio power which I bought from an eBay vendor. This really is the BEST #10 stranded I've ever handled, in 35+ years since my electrician's apprenticeship. An auspicious beginning.... I chose red for high beams, black for low and white for ground, just as Chrysler (or FoMoCo, who actually made the original, 53 yr old harness.) did. Best to be consistent in wiring conventions when adding new circuit elements to an old system.
The original headlight connectors have become quite brittle with age, as I found when replacing a low beam bulb a couple years ago with a junkyard buy. Be this as it was, I opted to keep them and just plugged a couple male slide connectors into the driver side low beam connector, nearest the battery where my relays
were to be placed. While the cheap sino-relay that came with my pusher-fan had a pre-fab harness wired
with #14 AWG wire, I purchased GOOD TYCO-BOSCH relays, made in Portugal for this job. I could find
NO relay connectors pre-wired in #10 gauge, which compelled me to just use 1/4 inch female slide
connectors.
The 4 circuit glass fuse holder from Dorman (Rock Auto purchase) worked perfectly for my design. I had already used two circuits for the cooler fan, leaving 2 spaces for the high and low beams. I use ONLY GLASS FUSES in Mathilda, and preferably Society of Fuse Engineers (SFE) certified ones.
Again, I'm blessed with some acquired from a deceased old duffer who hoarded treasures like these. Pity modern plastic fuses aren't tested or designed with the same old school rigor these were.
I fed the power supply side of my 2 30A fuses with a bit of #8 AWG wire, again meant to power audio amps and very finely stranded for maximum conductivity, straight from the top post terminal on the battery to the fuseholder, using a split brass bolt "kerney" to attach 2 short pieces of #10 to the two spaces on the
fuseholder and to the kerney. I use the same device for each of my two critical power connections, from
the alternator to the battery, then from battery to starter relay terminal post. The two 6 inch #12 AWG fusible links each attach to a kearney binding them to the #8 feeding the rest of the circuit. I might use a fusible link for the headlight feeds if I deem it likely that they might ever short. I HATE sacrificing ampacity for safety in such a setup, and the fuses DO protect everything below them. I might get a 10 gauge link instead if I lose sleep over this.
I have to stop this installment of my article here for now, having reached the limit on uploadable graphics. My server/workstation has also thrown an exception and needs a reboot.
To Be Continued.....