Quality Cable for Headlight Mod

[California Dreamin]

There is not much point in replacing the wires to the headlamps the original power cable is more than adequate, 16A cable carrying 5A not really a problem. Intercepting the earth wires and earthing them close to the headlamps halves the cable run and halves any voltage drop.
The main problem has always been the voltage drop through the ignition/headlamp and dip switches.

On a four light 'square lamp' model, the two outter H4 lamps use a 55/60 watt bulb. On full beam the 60 watt elements in the H4 bulbs come on at the same time as the two inner H3's, so thats 2 X 60watt = 120watts and another 2 x 55watts = 110watts 230watts total.
4 seperate elements, so close on 20 amps for full beam operation.

I've not looked at the wiring diagram for the wire ratings but from memory they certainly don't look very heavy, 1.5mm2 or 2.00mm2 at best. Certainly in the case of the 4 lamp version I would say that this was border line at best.

2 lamp versions are a different matter at 10amp draw.
The original wiring isn't redundant as it works well as a 'SWITCH' for the relays.


Martin

It's still only 9 amps running through 16A cable.

You got me mate? 230 (watt)s divided by 12 (volts) is 9 (amps?).....when it is actually 19.16 amps

You must be referring to a single lamp setup....which I guess with a more realistic 12.5 - 13volts volts would draw mid 9 amps ..but I did say that in my first reply!

Either way....getting the full regulated 14 volts plus (engine running) to those lamps is the aim of the game and the proof if definitely in the 'picture' pudding. lol
Even a moderate voltage drop will knock high percentages off the design lumens of those nice Nightbreaker bulbs.

Martin

[California Dreamin]

I note some talk about 4metre cable runs to those relays, you must be talking diesel battery as mine were under two to reach the starter battery in the battery box (behind the passenger seat, westy)
I wired my two 45amp cables directly to the positive battery terminal (separately fused of course)
Under load, the difference between voltages at the (battery & relay) was almost non existent (0.1volts) and combined with a decent regulator it is entirely possible to see over 14 volts at the bulbs.

Martin

[bigherb]

You got me mate? 230 (watt)s divided by 12 (volts) is 9 (amps?).....when it is actually 19.16 amps

Martin

Unless they made yours differently but all the ones I seen have a separate cable for left and right headlamps so that is halve your 19.6A through each cable.

[ghost123uk]

You got me mate? 230 (watt)s divided by 12 (volts) is 9 (amps?).....when it is actually 19.16 amps

Unless they made yours differently but all the ones I seen have a separate cable for left and right headlamps so that is halve your 19.6A through each cable.

Is that Checkmate then

Thinking outside the box for a moment - how about boosting the voltage to the bulbs instead. Could be easily done cheaply if your voltage is around 12 to 13v to start with, a 10A voltage converter (per headlight) could push it up to say 15v giving you room for a 2v drop to 13v. Up for discussion!

Or you could use an inverter to take it up to 240 volts AC, feed that up front (nice thin wires will be fine at that voltage) then use a step down transformer (to 14 volts) right behind each light On a serious note though, I note in the wiki on this, Ralph (CovKid) is using some sort of "ballast box" in his van, which I guess is some sort of voltage booster.

Hey Chris, that "before and after" pic is so good it should be added to the wiki entry on this topic, would you mind if I add it ?

[ghost123uk]

p.s. = With all this banter I forgot to say what I was going to say

Why use 2 (or 3) separate cables from the battery (esp if it's an oil burner) ? I used just one heavy cable from the battery +ve and split it behind the grill to the (2 in my case) relays. I don't know what rating the cable is, but going by it's size it is well good enough. It came from a mate who works for British Rail in the repair sheds (he got me a big bag of assorted "roll ends" ) It's really top quality (oil proof, fire resistant, high temp capable etc etc)

[CJH]

p.s. = With all this banter I forgot to say what I was going to say

Why use 2 (or 3) separate cables from the battery (esp if it's an oil burner) ? I used just one heavy cable from the battery +ve and split it behind the grill to the (2 in my case) relays. I don't know what rating the cable is, but going by it's size it is well good enough. It came from a mate who works for British Rail in the repair sheds (he got me a big bag of assorted "roll ends" ) It's really top quality (oil proof, fire resistant, high temp capable etc etc)

That's a good point, assuming that source cable is fat enough and reliable enough. I ran two separate circuits just for redundancy - one could fail and I'd still have the other, but yes, looked at it the other way I've now got more possible ways for my lights to fail Also, if I decide to add spotlights there's still some spare capacity in those two wires.

Be my guest with the photo by the way - I'm not sure it catches the full effect the way I wanted it to, maybe because it was dusk rather than dark, maybe because it was dipped rather than main, but the advantage is still clear.

[ghost123uk]

Will do the pic then Chris

Re cables, I think "we" don't need to go too mad here. As has been said, most of the loss is in the switch gear and connectors. We are not running a starter motor or a 2,000 watt stereo amp here. imho, and as has been said above, a (single) cable capable of 20Amps is well good enough (and is thinner than a pencil). Also, any thicker and making connections to "Lucar" spades for the relay, ring connector(s) at the battery end and a fuse (near the battery) gets much harder to do properly and neatly.



Slight aside. How are "you" making that last connection from the wires that actually come out of the bulb holder ?
I just cut them short, about 3" from the holder, and used a decent size "chockie blok" connector (used carefully I find them fine - always fold the bare wire back over the plastic though, so the screw is biting into the insulation, not the just the actual wire, then, if used "outdoors", give them a spray of aerosol grease or similar)

[CJH]

Slight aside. How are "you" making that last connection from the wires that actually come out of the bulb holder ?

I used replacement sockets - item 5736 half way down this page. I put the original connector on the OS inside the weatherproof box with the relays, and used male blade terminals on very short wires to plug into that socket to feed the relays. This means my original wiring is unmolested, and I could go back to it if necessary. On the NS the original plug is just zip-tied to the new wiring behind the headlight.

[ghost123uk]

@ CJH - Chris, your pic is now immortalised in the wiki HERE (at the bottom of the page).

[CJH]

@ CJH - Chris, your pic is now immortalised in the wiki HERE (at the bottom of the page).

Cool - fame at last!

[California Dreamin]

You got me mate? 230 (watt)s divided by 12 (volts) is 9 (amps?).....when it is actually 19.16 amps

Martin

Unless they made yours differently but all the ones I seen have a separate cable for left and right headlamps so that is halve your 19.6A through each cable.

I confess that I was very lazy and hadn't spent any time searching for a wiring diagram. If you say the feeds are split then of course you are correct.

As for over specifying wire gauge.....well I guess if you are going to go to all the trouble of doing the job in the first place then why wouldn't you? ....3mm2 27.5amp is just 19p a metre more than 2mm on the website I use and you have the peace of mind of knowing voltage drop over long runs, is being kept to an absolute minimum....it can't hurt is all I'm saying.
Martin

[Sir Brixalot]

I'd really like to do this but don't get the wiring diagram and discussions on draw etc. Would anyone be able to do a bullet point description of how to do this for thickos like me?

[CJH]

I'd really like to do this but don't get the wiring diagram and discussions on draw etc. Would anyone be able to do a bullet point description of how to do this for thickos like me?

Here you go, it's all laid out in this thread - there's even a parts list in there. I followed California Dreamin's approach - two fused feeds, two relays, weatherproof box, replacement light sockets, dedicated earth - and it works a treat. The discussion here is all about variations/different gauge wire/etc, and there are probably many variations that will give the same result, but Martin's method certainly works. There's also plenty in the wiki.

[Sir Brixalot]

Thanks. I did follow that thread but still didn't get it. Never done anything electrical my level is basic. Along the lines of being told which relay to which headlight and how to chase the wires all the way back to power/switch. The Osrams have made a big difference but if there's more brightness available I'd like to get it!