Headlamp relay updrade/mod

[badgerfax]

Hi, I'm following California dreamin's instructions for wiring up the new square lights.
In a few places it looks as though 2 cables will need to be wired into one connector but due to the size of the cables this looks difficult with standard crimps.

Was thinking of soldering in the line with heat shrink over the top.

Any other tips appreciated

[California Dreamin]

If it's a looped connection ie: from full beam H4 to the inner full beam H3 bulb, then the 'spur' off to the H3 bulb can be thinner as it is only supplying to one 55 watt bulb (around 5 amps) so a thinner 2.00mm2 (17.5amp) will be fine on this short run.
Also the H4 full beam feeds (off the relay which split into two) can be 2 X 2.5mm2 (around 22amps) if that helps soldering two wires into one yellow spade connector.
As long as you have around double the current rating on each wire, there won't be a significant drop over the short 400 & 1000mm runs to the lamps.

I would also suggest that the two wires are twisted together and soldered to make the wire easier to crimp on to a terminal...or better still, solder in the terminal.
So two big separately fused feed wires going to the two relays (35amp 4.5mm2wire as a minimum) this includes the two earths of the same gauge.
Split feeds off the full beam relay can be smaller, at 22 amp 2.5mm2
And the loop off's to the inner H3's can be smaller still at 2.0mm2
The feeds from the dip beam relay can also be just 2.00mm2 as they are just powering single 55 watt bulbs.

So I know this means lots of different wire sizes but if this helps with the terminals.....


Martin

[badgerfax]

Thanks Martin for replying, and also for the circuit diagram & parts list! This thread should be in WIKI as I have found very useful.

I have so far run in 3 cables from the batter 1 x 6mm 50A for main Beam, 1 x 4mm 39A for Dipped and 1 x 4mm 39A for fog lights that I may or may not fit.

Unfortunately I did not order thinner cables for the lower load parts of the circuit so may have to order more.

I see from your pics that you have fitted fuses in the box, Was there any reason for that? I have chosen to fit mine at the starter battery.

Also do I need to link the earth from left to right lights, I will be fitting new bolts in the bodywork as you have done and don't see the necessity.

I have also taken the relay trigger feed from the off side original bulb connector using standard spades, These are not as wide as the connector but seem to make a reasonable contact. I'm guessing the near side connector is just bagged up and left tucked away just in case I or someone else decides to return to standard.

Gary

[California Dreamin]

Thanks Martin for replying, and also for the circuit diagram & parts list! This thread should be in WIKI as I have found very useful.

I have so far run in 3 cables from the batter 1 x 6mm 50A for main Beam, 1 x 4mm 39A for Dipped and 1 x 4mm 39A for fog lights that I may or may not fit.

Unfortunately I did not order thinner cables for the lower load parts of the circuit so may have to order more.

I see from your pics that you have fitted fuses in the box, Was there any reason for that? I have chosen to fit mine at the starter battery.

Also do I need to link the earth from left to right lights, I will be fitting new bolts in the bodywork as you have done and don't see the necessity.

I have also taken the relay trigger feed from the off side original bulb connector using standard spades, These are not as wide as the connector but seem to make a reasonable contact. I'm guessing the near side connector is just bagged up and left tucked away just in case I or someone else decides to return to standard.

Gary

you definitely mean business with those heavy wires...nothing wrong with that! lol
Yes..you are right, I fitted fuses in the box with the relays as well as at the battery which I agree was unnecessary. However, given the gauge of wire and current flowing make sure you use heavy duty fuse holders (strip fuse holders perhaps).
I made a separate earthing post on both sides to minimize cable length (voltage drop occurs on both sides of the circuit, live & earth) so a short heavy earth will minimize any losses.
Yes..a standard 6.3mm male spade is slightly narrower than a bulb socket terminal but as it is just the trigger for the relay it is only carrying milli-amps and makes a sound enough connection.
Yes...just tape up and bag so none of the original wiring is cut.

Martin

[AdrianC]

I have so far run in 3 cables from the batter 1 x 6mm 50A for main Beam, 1 x 4mm 39A for Dipped and 1 x 4mm 39A for fog lights that I may or may not fit.

you definitely mean business with those heavy wires...nothing wrong with that! lol

<blink> Flippin' 'eck. That's some serious wire overkill alright!

Badger - divide the watts by the volts to get the amps... So two 55w headlamp bulbs, 110w, at 12v is a little under 10A!

[California Dreamin]

Yup...I guess if he's following my diagram then this is a late 4 lamp setup..so 20 amps on the full beam....still...50 amp cable is indeed heavy cable.


Martin

[ScienceBoy]

Yes something to consider if you only have 2 headlamps. Even for main beam you're only talking at 2x60W which is 10A at 12 v. But of course we're not talking about about being capable but being excess to address voltage drops.

An alternative to expensive high amp power cable - I just bought 5m of 25A speaker cable for £1/m at my local discount shop.
So that's 10m of 25A cable for £5

[scottbott]

the extra earth post you fitted and sprayed to stop corrosion,was it mild steel?, would a stainless steel nut and bolt be better to use?

[California Dreamin]

the extra earth post you fitted and sprayed to stop corrosion,was it mild steel?, would a stainless steel nut and bolt be better to use?

Earth posts 'both' sides...just anything that came to hand, but good quality HS steel bolts/nuts, star washes help to establish a good electrical connection....stainless steel would be better I suppose, however, painting and daubing with grease is going to be good enough. To be honest, its pretty dry at the back there, not really a place that is 'wheathered'.

Martin