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Optimum voltage for LEDs?

Discussion in 'Landscape Lighting' started by starry night, Jun 12, 2012.

  1. starry night

    starry night LawnSite Gold Member
    Messages: 3,268

    LEDs have a wide operating voltage but what is the optimum voltage?
    Is there a lower internal temperature at lower voltage? What about longevity?
    Noticeable change in color temperature at varying voltage?

    No doubt my question is born of ignorance of the fundamentals of LEDs but I haven't been able to determine the answer from previous threads.
  2. INTEGRA Bespoke Lighting

    INTEGRA Bespoke Lighting LawnSite Platinum Member
    Messages: 4,102

    Hi Phil. The fast answer is: It depends. Each type of LED lamp or fixture is going to be a bit different. With so many varieties on the market it is pretty much impossible to tell you an optimal voltage for all. I would recommend you operate any LEDs that you use in the middle of their rated voltage range.

    LED drivers (the electronic circuits that are typically part of the lamp or fixture) are essentially power conditioning circuits. They accept a wide variety of input voltages and then adjust that voltage to whatever the chip requires to operate effectively and efficiently.

    "Is there a lower internal temperature at lower voltage?" Not typically.

    "What about longevity?" Input voltage variances do not typically affect longevity as the driver is adjusting your input voltage to provide what is most effective for the chips.

    "Noticeable change in color temperature at varying voltage?" In non-dimmable LEDs there would be no change in colour temp at varying input voltage. With most dimmable LEDs this is also the case. Only recently I saw one chip manufacturer offering a series of chips that will warm up as they are dimmed, thus emulating the effects experienced with incandescents as you dim them.

    Hope this helps.
  3. steveparrott

    steveparrott LawnSite Bronze Member
    Messages: 1,276

    Agree with James on most items.

    Depending on drive circuitry - middle of range is best bet, lower and upper ends of range may stress components. Plus, you want to guard against changes on the 120v side that could push secondary voltage past limits.

    There should be no color change in range.

    Driver temperature does change with voltage in most types of circuits - lower voltage - lower temps. Longevity of chips should be maintained throughout range since a constant current is supplied to the chips regardless of input voltage. But longevity of driver is suspect if capacitors overheat regardless of voltage (though they will get hotter at higher voltages).
  4. David Gretzmier

    David Gretzmier LawnSite Gold Member
    Messages: 3,645

    I agree it depends. but failures I have heard of seem to happen on the very upper and lower end of the range. outside of that is asking for it.

    a larger question is what voltage the LED itself is best at, and you can't fiddle with that anyway. The factory driver does that. all LEDs do have a point at maximum lumens per watt are achieved, with the least amount of heat ( waste) generated for given lumens. but manus lean more towards longevity than max lumens per watt.
  5. steveparrott

    steveparrott LawnSite Bronze Member
    Messages: 1,276

    I wouldn't assume that - some mfgs are conservative in their driver designs - others push the envelope - increase amperage through chip to get max. lumens - this can be bad news if thermal managaement is poor..

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