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Old 04-01-2013, 10:02 PM   #1
willett
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relays for running high intensity h4's?

Hi guys,

I upgraded to h4's a couple years ago, but the bulbs in there are pretty crappy. I was thinking about upgrading to some better bulbs but have a friend who did the same thing and ended up frying 3 headlight switches before going back to crappy bulbs.

I was thinking of just using a couple 12v/30A bosch 5 prongers. does anyone see a problem with this? should I run a single relay for both sides, or a seperate relay for each light. I can't really see 2 headlights pushing 30A.

I'm running round headlights (pre-80 style)

as well, who makes a bright h4?
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Old 04-01-2013, 10:43 PM   #2
JellyBeanDriver
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Re: relays for running high intensity h4's?

People do this all the time.
Single relay for both sides, one for high beams, one for low.

The factory wires are thin and through all the connectors the voltage drop to the lamps are high.

Come directly off the battery either through a breaker or a fusible link feeding the relays.
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Old 04-01-2013, 11:15 PM   #3
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Re: relays for running high intensity h4's?

yeah have like he said.. one for hi one for low,

then just turn them on with the stock wires.
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Old 04-02-2013, 01:35 AM   #4
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Re: relays for running high intensity h4's?

How much draw can I expect to be fusing for?
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Ed.
P/IE. right... Wattage should be on bulb box...
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Old 04-02-2013, 01:44 AM   #5
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Re: relays for running high intensity h4's?

W/v = a
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Old 04-02-2013, 03:27 PM   #6
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Re: relays for running high intensity h4's?

You can look into the sylvania silverstars alot of people like them with relays. Should take alot of hassle out of wiring for 5 prongs
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Old 04-02-2013, 06:31 PM   #7
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Re: relays for running high intensity h4's?

I am in no way affiliated with this vendor, but I do think they have a very well assembled kit: 1973-1987 Chevy & GMC Heavy Duty Headlight Relay Harness
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Old 04-03-2013, 12:02 AM   #8
JellyBeanDriver
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Re: relays for running high intensity h4's?

Quote:
Originally Posted by willett View Post
How much draw can I expect to be fusing for?
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Ed.
P/IE. right... Wattage should be on bulb box...
Depends on the H4 bulbs you are using.
Use a breaker if possible. Thermal breakers are slow to respond - helpful for devices with high inrush current like lamps and motors to prevent nuisance trips.
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Old 04-03-2013, 03:29 AM   #9
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Re: relays for running high intensity h4's?

Take a look at the wiring harness that Painless sell for the higher wattage bulbs. The harness comes with two relays and 12 gauge wiring to handle the load. YOu can build a similar wiring harness with items from a parts store, but it takes time and you will have to purchase a pair of male plugs to allow you to tap the headlight circuit for you new relays to actuate.

I would at lest try to copy this for longevity

http://www.painlessperformance.com/w...rchField=30817

http://innovativewiring.com/?page_id=1291
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Old 04-03-2013, 07:49 PM   #10
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Re: relays for running high intensity h4's?

IMHO there is no need to buy all that. That's way too expensive. I just got two relays and used 18 ga. wire. Made for a nice H4 conversion. Did it about a year ago, still working great today. Bought these headlights:

http://www.ebay.com/itm/4x6-H4651-H4...d02531&vxp=mtr

Bought these nice relays with the fuse already in 'em. So you don't have all that ugly bulk of running in in-line fuse:

HELLA 003530041 12V/25 Amp SPST Mini ISO Relay... HELLA 003530041 12V/25 Amp SPST Mini ISO Relay...
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Old 04-04-2013, 02:11 AM   #11
85sierraclassic
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Re: relays for running high intensity h4's?

Something like this work? http://www.carid.com/universal-light...FaZFMgodRQ0Amw
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