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do halogen lights need relays?

12K views 22 replies 9 participants last post by  adantessr 
#1 ·
I've always used relays on elec fuel pumps,elec fans,& horn. I know they won't hurt to use them on anything,but do you really need them with halogen headlights? I thought they use less juice than sealed beams.
 
#2 ·
do halogen lights need relays

yragat said:
I've always used relays on elec fuel pumps,elec fans,& horn. I know they won't hurt to use them on anything,but do you really need them with halogen headlights? I thought they use less juice than sealed beams.
I have wired a lot of cars and have never used relays on halogen, and I believe I have used them on every car. :thumbup:

35terraplane
 
#4 ·
RElays on halogen

302 Z28 said:
If the car is OEM wiring and did not come standard with halogens then YES you need to run them off relays with the appropriate wire size feeding the lamps. OEM wiring is usually insufficient for that added amperage draw of halogen lamps.

Vince
I agree on OEM wiring on car that didn't come with halogen. I was rewiring the whole car so used wire that was the right size and never used them.

35terraplane
 
#6 ·
halogen lights

yragat said:
so if the wire is the right gauge then you don't need the relays---is that right?
What is the correct gauge wire to use with halogen's?
I use 14ga. and that's all the way from the light switch to the dimmer switch to the headlights. Now I wire street rods not newer cars, so when I wire the lights I put a small terminal block on the inter fender and run the wires to that, then from there to the headlight, whatever is on the fender, turn signal, ETC. Then I use a Ron Francis headlight kit from the light to that terminal block. His kit is about $20.00 or so, but all the wires are in a rubber or plastic. Anyway I do this so if you ever have to take anything off the front end you don't have to cut wires. Take a fender off just unhook the wires that you need to. I also put a terminal block on the inter fender on the Pass. side for the same reason. Been doing it over 30 years like that, never had a car come back. :thumbup:

35terraplane
 
#10 ·
halogen bulbs

I didn't need a relay on my '57 Chev. In fact I have not needed relays in anything I have converted to H1 bulb - type lights. My buddy didn't need a relay on his '64 Malibu - until he put the H1 lites in his hi-beam sockets along with the H4 (dual filament) ones in the low beam positions. THEN, if he hit the high beams, things got silly, with overloaded breakers, flickering lights etc. So I wired in a couple of relays - and all is good! (Come to think of it, once upon a time wifey had a '77 Monza Spyder and it would not tolerate long runs with High beams after I had put the Bosch H4 and H1combination in it, too! (Needed a relay in that one, too!)

If I had just replaced the low/high beam lights with the H4 set , it likely would have been OK sans a relay, but changing the High-beams to H1s in addition.....
 
#11 ·
Dave57210 ,

Did you notice how much heavier the wire was in the '57 and '64 as compared to the '77 ? My '75 Nova had "aluminum" wiring to the rear lights . Yikes ! And I couldn't believe the size of the wiring to the headlights on my '99 Silverado . It looked like 18 or 20 gauge .
 
#15 ·
Ohms law

If I remember Ohms law correctly . Watts / volts = amps . So if you have 150 watts on a 12 volt system = 12.5 amps x 2 = 25 amps draw . You can figure out from this what you need to do . 14 gauge wiring is only rated for 15 amps . So plug the wattage of your lamps into ohms law and decide from there . Hope this helps .
 
#16 ·
halogen light

adantessr said:
If I remember Ohms law correctly . Watts / volts = amps . So if you have 150 watts on a 12 volt system = 12.5 amps x 2 = 25 amps draw . You can figure out from this what you need to do . 14 gauge wiring is only rated for 15 amps . So plug the wattage of your lamps into ohms law and decide from there . Hope this helps .
All I have used is 14ga when I put in halogen lights, never put any relays in, and never had any trouble with them. :thumbup:

35terraplane
 
#17 ·
35terraplane said:
All I have used is 14ga when I put in halogen lights, never put any relays in, and never had any trouble with them. :thumbup:

35terraplane
With ya there Bob. Never checked the wattage on a 12 volt halogen . We had 65 and 100 watt 24 volt mini bulbs on our mine equipment which were fine , but then some of the operators found out we had some 150 watt 24 volt sealed beams = 6.25 amps . We were okay until some guys tried to put 4 on one circuit and couldn't figure out why the 15 amp auto reset breakers wouldn't hold . Some operators wanted us to install heavier breakers . Had to explain ohms law to the mechanics and the operators and tell them we were not going to rewire a $750,000 machine because they were scared of the dark . Yeah , heavy equipment builders skimp on wire also and often use only 15 amp circuits with 14 gauge wire .
 
#18 ·
halogen lights

adantessr said:
With ya there Bob. Never checked the wattage on a 12 volt halogen . We had 65 and 100 watt 24 volt mini bulbs on our mine equipment which were fine , but then some of the operators found out we had some 150 watt 24 volt sealed beams = 6.25 amps . We were okay until some guys tried to put 4 on one circuit and couldn't figure out why the 15 amp auto reset breakers wouldn't hold . Some operators wanted us to install heavier breakers . Had to explain ohms law to the mechanics and the operators and tell them we were not going to rewire a $750,000 machine because they were scared of the dark . Yeah , heavy equipment builders skimp on wire also and often use only 15 amp circuits with 14 gauge wire .[/QUOTE

You had said that your suv had 18 or 20 ga. they must of had relays on them. :D That's why I don't work on new stuff my hands are to crippled up. :( Guess I'm going to have to look harder for a place in FL. Six months ago I had cash in hand to buy one but back out, but with 2" of snow yesterday and today snowing on and off I'm ready to move. :thumbup:

Bob
 
#21 ·
halogen light

302 Z28 said:
Try feeding you halogen lamps with a fuse protected #10 AWG right from a battery terminal and bask in the improved illumination. :thumbup:

Vince
The lights are fed right from the IGN Bat. terminal so it is coming from the bat. :D I have tried it right off the battery with 10, 12, and 14ga wire and through the switch I didn't think one was brighter than the other. :thumbup:

Bob
 
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