Thread: headlight and relay questions

Hi,

Drivesafe has done the work for you.

Either make one of these or buy a kit from him.

http://www.aulro.com/afvb/projects-t...-up-grade.html

http://www.aulro.com/afvb/projects-t...-up-grade.html

I made the one with the standard type relays. Makes a huge difference in light output.

Either way the diagram in the first link has the answer to your relay wiring question.

2 relays per headlight is kinda overkill, even the chunkiest H4 lamp i know of draws less than 15 amps on high beam, and a quality relay will handle 40 amps, get a relay with twin #87 terminals

Originally Posted by Sprint

2 relays per headlight is kinda overkill, even the chunkiest H4 lamp i know of draws less than 15 amps on high beam, and a quality relay will handle 40 amps, get a relay with twin #87 terminals

DS used 4 relays as a failsafe. Same as the two fuses control one high beam and one low beam each.

Originally Posted by Sprint

2 relays per headlight is kinda overkill, even the chunkiest H4 lamp i know of draws less than 15 amps on high beam, and a quality relay will handle 40 amps, get a relay with twin #87 terminals

Fitting a relay each side each beam is insurance against failure. Failure is not only due to exceeding the electrical capacity of the relay. Wires break, terminals fall off, fuses come loose. Not nice to lose lights at speed on a country road. This is why the Irish use two rubbers, "to be sure, to be sure".

Originally Posted by Brian Hjelm

Fitting a relay each side each beam is insurance against failure. Failure is not only due to exceeding the electrical capacity of the relay. Wires break, terminals fall off, fuses come loose. Not nice to lose lights at speed on a country road. This is why the Irish use two rubbers, "to be sure, to be sure".

No wonder their lights don't work, don't they know that rubber is an insulator

G'day azz

I have just finished doing a headlamp upgrade on a classic range rover, using a "New Era" 30 amp,double fused relay, and a 30amp circuit breaker, with a seperate 5 pin narva relay,(double 87 pins)not 87-87a, powered from the high beam circuit side of the twin relay, the light improvement is quite noticable,it also removes the power/amp draw through the switch


cheers

Originally Posted by UncleHo

also removes the power/amp draw through the switch

cheers

Which can cause the switch to melt if you have higher powered globes than standard.

Willem

Willem, it will not cause problems with the switch, quite the opposite- the switch is now conducting only the current required to activate the electromagnet in the relay rather than the current for the lamps themselves.

I have made this simple modification on many vehicles over the years. I will no longer use the common plug-in type relays. My experience has been that after a while as the contacts wear, the relays fail not by failing to conduct but rather by the contacts 'welding' together so that the lamps stay on when you switch them off. Thus you are unable to dip your lights without getting out and giving the relay a tap with a spanner or pulling the wire. I have also had this occur with the 'new era' twin-circuit headlamp relay running only 1 super-oscar (100w) through each circuit.
The driving lights on my RR now run through a starter relay (solenoid). As this will handle 150amps, I don't anticipate overloading it. Also provides a handy 'bus' for other circuitry. Surprisingly, the switching circuit on these heavy-duty starter relays draws the same current as the switching circuit on the little plug-in type, approx 600milliamps.
Another key to getting the best out of your headlamps & driving lamps is to use the heaviest guage wiring practicable when installing the relay circuit.