headlight relay question

[Toqwik]

I am running 31 desoto lights with a halogen conversion in them. Do I have to use a relay, and if so, what is the purpose of it???? Scott

[DrJ]

Relays are usually used because they are designed to carry high amperage draws that the dash switch cant handle without burning up it's contacts. The switch activates the relay and that part of the relay is low draw then the relay "switches on" thehigh amp circuit.
If you have a switch capable of carrying the amps of the lights then you don't need the relay. I've been running H4s for over a decade thru a Pep Boys aftermarket headlight switch, the one with the cheesy tan knob, and haven't brned it out yet. and my H4s are European, high candlepower units too.

When in doubt, use the relay.
But, If you know you don't need it, it's just one more thing that can go wrong.

[yorgatron]

http://www.chevyhiperformance.com/howto/4417/index.html

[Toqwik]

thats interesting, thanks for the link....To