Headlamp relay, wiring and fusing

[p7rider]

Bringing this topic to life again. I bought the same relays/wiring harness as others from ebay. 

To me it looks like too many wires as i do not wish to run a separate connector to each light ,

Cutting the terminal block from one set of wires and fitting 2 bullet connectors i fitted these to 2 the original 4 hole connectors(black plastic covered) . these then take a wire to each light as original . to me this is more straight forward. But without using the other terminated lead am I overloading the single run? I hope this makes sense

 

 

[dougbgt6]

p7,

Uh, no. Explain it again, I'm very old. Do you have diagrams?

Doug

[p7rider]

9 hours ago, dougbgt6 said:

p7,

Uh, no. Explain it again, I'm very old. Do you have diagrams?

Doug

I have no idea how to add a diagram  . Basically one feed into existing wiring loom feeds both lights because they are tee"d off. 

[Iain T]

I bought two relays, one for dipped and one for mains. It still needs tidying but the headlights seem brighter. I fitted both horns onto the drivers side which left more room for the cable spaghetti on the nearside. I fitted the relays on to a bracket bolted to the horn bracket at the front of the bonnet. As a live feed I ran two 15 amp fused cables from the alternator to each relay. 

Have fun, I had about four permutations and still not happy with the appearance! I'm thinking a busbar for the four main beam (it's a Vitesse) cables then one to the relay. At the moment it looks a mass of connectors! 

Back to adjusting the angle of my quarterlight today! 

Iain 

[Phil C]

Very interesting read but as I am still not sure please can I bring this topic back to life briefly?

I have just fitted headlight relays to my Vitesse. and have concerns re power draw for main beam.

I bought a two relay kit with each relay rated at 40A cont/80A peak.

Ive fitted them under the dash cutting the supply from the column switch and using that to activate the relays. I then ran a single supply from the fuse box to the relays and each relay connects to the relevant feed to the front of the car.

The wire used for the feed/connections was sourced an old loom (main beam feed) so should be the correct gauge (?)

My question is when on main beam (220w) is it normal for the feed wire to be warm and the relay a little warmer?

My headlights are upgraded with H1/H4 bulbs and the wiring loom is new.

Am I worrying about nothing or is my car about to burst into flames!! 🔥

 

Edited September 17, 2023 by Phil C

[chrishawley]

15 hours ago, Phil C said:

on main beam (220w) is it normal for the feed wire to be warm

Hmmm. Seems like a borderline case to me. Most probably safe (esp. since you have the circuit fused) but not really right either.

As a starter it's worth looking at the feed wire used if you still have a snippet to hand. If you pick it apart and count the number of individual strands which will most likely be 9, 14, 28 or 44. 'Continuous amps' is number of strands divided 2 as a rough rule. So for 4 x 55w (approx 17 amps)  a 28 strand wire is the minimum.

I've no experience with warm relay - so hopefully another member can comment on that.

[johny]

Not worried about the warm relay as the coil has resistance and current flowing through it which equals watts in the form of heat of which theres not much dissipation so the temperature will rise slightly... 

[Phil C]

12 hours ago, johny said:

Not worried about the warm relay as the coil has resistance and current flowing through it which equals watts in the form of heat of which theres not much dissipation so the temperature will rise slightly... 

The thing is the dip beam relay doesn't get anywhere near as warm.

For my peace of mind Ive ordered another relay and will have two for main beam. Each will have its own direct feed and supply two of the four lights. It may not be necessary but its cheap and should ensure all will be well.

I'm doing the RBRR in three weeks time so need the lights to be reliable!

Edited September 18, 2023 by Phil C

[johny]

Hmmm that points to relay contact resistance generating heat which isnt good and can lead to a downward spiral. Are they genuine quality relays?  

[Phil C]

1 hour ago, johny said:

Are they genuine quality relays?

I bought a kit from a very well known spares supplier. They sell lots of them so hopefully they are ok. Not guaranteed though as there is a lot of rubbish sold these days !

 

[johny]

Agreed. They wont be Bosch or Durite but some far eastern offering but should do the job ok

[Phil C]

On 18/09/2023 at 09:51, chrishawley said:

So for 4 x 55w (approx 17 amps)  a 28 strand wire is the minimum.

Just checked and the feed wire has 28 strands. On the limit I suppose.

Still going with two feeds and two relays for main beam. Belt and braces approach 🫤

[PeteH]

220W on a 4 headlamp system. Is pushing the envelope for the standard wiring and switchgear. (@12V nom that is 18+amps) Even if the Alternator/Dynamo was outputiing 14V it`s still 15+amps. Add in the resistance of older wiring and terminations, it is little wonder that cable heats up!. Fitting Relays, and upgrading the wiring has to be beneficial?. I used 4mm/56 strand cable to wire in 200W of solar panels on the Previous Motohome, with an efficiency of (say) 20%/30% one will rarely get more than 5Amps on a good day, and more often far less than that.

Pete

[Phil C]

On 19/09/2023 at 13:51, PeteH said:

220W on a 4 headlamp system. Is pushing the envelope for the standard wiring and switchgear.

Agreed. I have now fitted a third relay and have two feeds direct from the fuse box.

Feed 1 for relay 1 (Dip) and relay 2 (outer main).

Feed 2 for relay 3 (inner main).

Nothing is now getting warm 🙂

Thank you all for your input.