Thermal cutout?

[Matt]

Most moden cars with halogen head lamps as most +2 now seem to have, use a 10amp fuse, even old minis with the sealed beem units used a 10amp fuse.

Changing to relays and more wiring seems a tad over the top no?

[Robbie693]

Dragging this one up again.

I checked all the wiring and cleaned it to try and stop the lights cutting out. I discovered I have H4 60/55W bulbs fitted. Is this too high for the original wiring and would this be the cause of the cutout operating?

Robbie

[Hamish Coutts]

Robbie,

60/55s would seem ok. That's what mine had fitted.

Another advantage of using relays (apart from lessening the chance of a cut out) is brighter lights. You can run a really beefy power cable to the relays and if you like, a beefy cable from the relay to the headlights. That way you reduce the voltage drop at the headlight - thus brighter lights. (of course, remember to beef up the earth conections as well).
The secret of bright lights is voltage!

Also because you are now using relays and beefier cables, you can fit higher wattage bulbs in the headlights. There will be no cut out problems because all the cut out will 'see' is the relay coil current.

Hamish.

[Robbie693]

Thanks Hamish.

I like the idea of fitting relays, if only my electrical skills were up to it!

I'll have to brush up on some basic theory.

[type36lotus]

Just about any automotive parts supplier can sell you a thermal self resetting circuit breaker. At worst case you headlights will flash as the CB heats and cools. This what I believe modern cars do as well, safety, but usability.