Are relays necessary for led headlights?

[oldiron]

Are these a must have type thing? I was under the assumption that the whole point of leds was to lower the amp load on the wiring harness. If my math is right the led bulbs should draw 2.5-3.3 amps. Am I missing something? Greg

 

[B RON CO]

Hi, I think headlight relays are good for all old Ford's.
The stock headlight switch cannot handle a large electric load and will fail, even with stock sealed beams. Good luck

 

[Broncobowsher]

Good LED lights have constant current drivers in them. That is the LED will run a wide range of voltages and be exactly the same brightness. Unlike filament based light bulbs that vary light output depending on the supply voltage.

If the LED lights vary output with voltage, dim while cranking, get brighter once started, act like filament based light bulbs. Yes, relays are a good idea.

But the good LEDs. Ones that are just as bright no matter if the voltage is higher or lower. Relays are just another failure point that serve no performance gain. So you have a small voltage drop through the stock wiring. The good LED bulbs are doing what they are engineered to do, work exactly the same over a wide range of voltages.

I have a motorcycle with no battery. With a conventional bulb the light output varies with engine speed. Idle is dim and worthless, rev the engine and the light gets bright. Put a nice Rigid LED in it. Operating voltage is 9-36V. That light has the exact same (excellent) performance through the whole RPM band now. Not sensitive to voltage changes at all.

 

[SteveL]

LEDs will be fine on the stock wiring.

 

[oldiron]

Thanks for the replies. These are designed to operate in the 9-30 range.
It'll be a couple of weeks before I can install them, but I'll measure the amp load and post up the findings then.
Greg

 

[DirtDonk]

Another variable is new wiring. While I'm still a fan of relays in general (but agree that they are an added potential failure point) a new wiring harness is a HUGE upgrade in wiring to the headlights all on it's own.
With regular halogens though, where you have higher wattage, they're still good simply for taking the load off of the switch. Not necessarily needed for additional brightness.

All of my trucks have headlight relays and horn relays. And someday maybe even a heater motor relay.

Paul

 

[blubuckaroo]

This same topic came up the other day about house wiring. When will the traditional 15 amp lighting circuit be replaced with something smaller? You can run one hell of a lot of LED lights on 15 amps!

 

[Boss Hugg]

Just for future reference my led lights are surplus military stuff from eBay. They run about 2.6 Amps at “On” and ease down to a low of 1.9 when warmed up. I was amazed.


Sent from my iPhone using Tapatalk

 

[Scoop]

Pondering the same issue - my 72's stock headlights have gone into flashing mode when on for more than a few minutes. I've decided to switch to LED headlights AND get a new headlight switch and floor dimmer switch. No relays.

 

[rjrobin2002]

I build boats and wire all kinds of lights and light bars with just toggle switches and they never have any load on them,. The LED minimal amp draw is amazing.

 

[nvrstuk]

blubuckaroo...problem is code would have to change to ONLY have lights access to that circuit...

No retrofitting should be allowed because stoooopid people would plug 15amp draw portable heaters into it and then a lot of houses would be on fire...

14 ga wiring isn't meant for heaters...