| A Question About LED Headlights and Wiring Harnesses [message #317945] |
Tue, 23 May 2017 23:25  |
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SteveW
Messages: 538
Registered: June 2005
Location: Southern California - Ora...
Karma: 1
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Greetings from Southern California !!
I'm familiar with the strategy of rewiring traditional headlights with a "relay" wiring harness such that all current doesn't flow through the headlight switch and voltage drop is minimized.
If one were to replace our headlights with new technology LED headlights and their lower current draw - would this "relay" harness stIll be beneficial ??
Thanks in advance for your answers and comments. I truly appreciate all of the helpful advice that's shared here.
Steve W
1973 23'
Southern California
Steve W
1973 : 23'
Southern California
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| Re: [GMCnet] A Question About LED Headlights and Wiring Harnesses [message #317947 is a reply to message #317945] |
Wed, 24 May 2017 00:06  |
richshoop
Messages: 190
Registered: April 2017
Karma: 0
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I would retain the relay. I would also suggest using one wire size larger wire than suggested. Note that LED's are current driven devices, the controller for the LED's will have an easier time of it with clean, minimum voltage dropped, power. Eliminating the relay does eliminate that as a possible failure point, but a properly rated and sized relay should have a lifetime of at least 100,000 cycles, most will do 1 million.
If you eliminate the relay and just run the lights directly through the switch who knows what size wire is used, we are talking about 40 year old vehicles here, what kind of condition the contacts are in, and possibly multiple switches.
BTW checkout www.delcity.net and www.waytekwire.com for wiring supplies
----- Original Message -----
From: "Steve Weinstock"
To: "gmclist"
Sent: Tuesday, May 23, 2017 9:25:19 PM
Subject: [GMCnet] A Question About LED Headlights and Wiring Harnesses
Greetings from Southern California !!
I'm familiar with the strategy of rewiring traditional headlights with a "relay" wiring harness such that all current doesn't flow through the
headlight switch and voltage drop is minimized.
If one were to replace our headlights with new technology LED headlights and their lower current draw - would this "relay" harness stIll be beneficial
??
Thanks in advance for your answers and comments. I truly appreciate all of the helpful advice that's shared here.
Steve W
1973 23'
Southern California
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| Re: A Question About LED Headlights and Wiring Harnesses [message #317948 is a reply to message #317945] |
Wed, 24 May 2017 00:13 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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People install relays to reduce the current across the light switch and wiring. The relay coil only draws a minimal amount of current and the relay switches the higher current for the light(s) over a shorter path. A shorter path means less voltage drop and brighter lights. Since LEDs draw much less current and most are rated for the same amount of light output at 10 to 30 volts, the benefits of using a relay is reduced or eliminated.
Don't bother installing a relay with LED lights.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] A Question About LED Headlights and Wiring Harnesses [message #317952 is a reply to message #317948] |
Wed, 24 May 2017 07:12 |
Richard Denney
Messages: 920
Registered: April 2010
Karma: 9
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Even with the regular headlights, the difference is minimal. It's a good
idea to wire in a load-reduction relay for higher-wattage lights (back in
the day when such were available). The standard sealed-beam headlight was
55 watts low beam and 60 watts high beam, as I recall from some deep
memory. Cibie and other companies of yore sold non-DOT-legal "off-road"
(I'm making quote signs in the air) headlights that were rated at 100/110
watts, or something like that. That doubled the current draw which
overtaxed the circuits and the switch, and increased the voltage drop.
Those headlights really needed a load-reduction relay.
I was just looking at the specs for the Grote 90951 LED replacement for a
sealed beam headlight. These are expensive! They don't rate it by wattage,
but the current draw for the high beam is 2.13 amps at the nominal 12
volts--no more than half of conventional sealed-beam bulbs. Also, they work
with 9-32V systems (for compatibility with 24V systems) and so I suspect
they are voltage-regulated in any case. The advantage to LED, it seems to
me, is that they DON'T need all the extra load-management stuff.
Rick "who would be attracted to the Grote replacement were it not nearly a
full GMC cost unit" Denney
On Wed, May 24, 2017 at 1:14 AM, Ken Burton wrote:
> People install relays to reduce the current across the light switch and
> wiring. The relay coil only draws a minimal amount of current and the relay
> switches the higher current for the light(s) over a shorter path. A
> shorter path means less voltage drop and brighter lights. Since LEDs draw
> much
> less current and most are rated for the same amount of light output at 10
> to 30 volts, the benefits of using a relay is reduced or eliminated.
>
> Don't bother installing a relay with LED lights.
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
'73 X-Glacier 230 "Jaws"
Northern Virginia
Offlist email: rick at rickdenney dot com
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| Re: A Question About LED Headlights and Wiring Harnesses [message #317954 is a reply to message #317945] |
Wed, 24 May 2017 07:51 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Keep in mind the GM headlight switch is also a self resetting circuit breaker. If you use that signal to trip a relay, you need to put some sort of appropriate (lower rated) self resetting breaker supplying the switched side of the relay. If you fuse it and the fuse blows you are in the dark. On the GM setup if there is a short or partial short (bad lamp) the lights will cycle on and off.
John Lebetski
Woodstock, IL
77 Eleganza II
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