Head light dimmer

[Cobra,1]

Getting ready to upgrade my factory txt holegen light bar with l e d replacement.
One thing I noticed around campground is l e d lights can be too bright depending on where cart is driven.
Has anyone installed a dimmer switch like maybe a reostat to dail up or down voltage to lights? L e d’s seem tolerant of voltage amounts.

Just trying to figure out what spec dimmer (dial) I would need.
Do I install hi lo voltage switch to headlights to reduce voltage via resistor or can I use a dial type veritable resistor to dial back voltage to lights.

Currently using two separate switch’s, one for head lights,one that turns on turn signal bulbs that have been changed out to white,not yellow bulbs on my factory light bar.
Ideas?😊

[cgtech]

Since LEDs are actually very sensitive to voltage, they always have a power supply to regulate input power down to what the leds actually need. I think undervolting that power supply to dim the lights would damage the power supply part of the light bar before long.

[cgtech]

Heres a look at the truth of how sensitive leds are to voltage increases & decreases.

Increasing its voltage by 0.5v (from 3.0v to 3.5v) increases it's current draw 5X. Just 0.5v is the difference between max light output and frying in seconds. Since we are looking at voltages in the "3v range", clearly the leds arent being fed directly by the 12v input. That means a power supply is used to carefully supply correct voltage to the leds themselves. Using a dimmer on it will likely have one of 2 results, either they stay at full brightness until they just turn off when input power gets too low, or you are operating the power supply in voltage ranges it isnt designed to handle (likely shortening the power supplys life).


This chart isnt perfect, (A) should say (mA), and different color & brand leds have slightly different voltages and acceptable power ranges, but this type of curve is representative of all leds as far as I know. I have built my own led light bars, and have never fried a high power led, because I very carefully adhered to the guidelines given by the led maker. Another tricky thing is that a led draws more current as it heats up. So, if you drive an led by voltage alone, it's current draw will increase as it warms up (maybe even to the point that you are using too much power/making too much heat for the led to dissipate).

[Sergio]

cgtech is correct about reducing the voltage would not dim an LED headlight, but most LED drivers used in those light bars are compatible with PWM dimming.

You can try a cheap high power PWM LED dimmer to see if it works with your lights:

https://www.amazon.com/SUPERNIGHT-12...952133-0237056

They make different models, some have the potentiometer separate so you can mount on a dash.

You can also wire a SPDT (3-terminal) switch so one side is full brightness and the other side is whatever you have dialed on that dimmer.

You just need to remember the SPDT switch needs to switch the negative wire to the LED bar as most of those PWM dimmers are "low side" drivers.

[Cobra,1]

Great feedback
I think I’llkeep my main headlights and turn signal (white) separated via on/off toggle switch.
I will keep turn signal/ used as running lights now main head lights on main key on light switch.
But controll main headlights on/off thru toggle switch. Wired reverse what I have them now.

FYI the problem is new led’s are too bright.

Factory Second position key switchposition will turn on running lights instead of head lights.
Toggle switch will interrupt voltage to main led head light bulbs as to not blind opposing drivers.
Never expected led replacement bar would be soo bright 😊

[Cobra,1]

Just a follow up.
Wired new led replacement head lights same as factory lights where second key position turns them all on. Then wired a 12 volt toggle switch on wire going to main head lights to turn on/off depending when main head lights are needed or not.
Thanks for the feedback on leds 👍