12-24v lights. Does input voltage change output brightness?

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Atomician

Atomician

Well-Known Member
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Location
Southampton, UK
So I've had some old LED spots in the back for a while that I was going to fit on my freebie. Noticed that the input voltage is listed as 12-24v. I get that a range is necessary as some commercial vehicles use 24v systems.

However was wondering if the input voltage would change the light brightness? Occured to me there's probably a normaliser in the circuit board to limit it all to the same current, but I thought if its likely I'll get more light from a 24v input, I could buy a step up transformer from 12 to 24v to get the most out of the lights.
 
A 'normaliser' ?

LED's need arount 1.5 to 2V, if this voltage is exceeded they draw an infinite amount of current and (essentially) die.
An LED needs a DC voltage so infront of the device is an AC/DC convertor a couple of transistors and a DC to DC convertor.
In automotive circuits the AC/DC convertor isn't neccessary of course.
This DC circuit (called a buck) has an input and output range.
Fall below or exceed the input voltages and it won't output a constant (converted) DC voltage.

So increasing the inpur voltage from 12 to 24V will have no effect whatsoever on the output or the brightness of the bulb.
 
A few of the lights I fit at work say 12/12/32 volt, I have tried some of them on 12 and 24v, they seemed much the same brightness wise.
Though it has to be said some of them will literally run on fresh air as they use so little current.
 
miktdish said:
A 'normaliser' ?

LED's need arount 1.5 to 2V, if this voltage is exceeded they draw an infinite amount of current and (essentially) die.
An LED needs a DC voltage so infront of the device is an AC/DC convertor a couple of transistors and a DC to DC convertor.
In automotive circuits the AC/DC convertor isn't neccessary of course.
This DC circuit (called a buck) has an input and output range.
Fall below or exceed the input voltages and it won't output a constant (converted) DC voltage.

So increasing the inpur voltage from 12 to 24V will have no effect whatsoever on the output or the brightness of the bulb.
Click to expand...
LEDs need various voltages. Depends on the LED in question, how it’s wired and what kind of driver.
 
Atomician said:
So I've had some old LED spots in the back for a while that I was going to fit on my freebie. Noticed that the input voltage is listed as 12-24v. I get that a range is necessary as some commercial vehicles use 24v systems.

However was wondering if the input voltage would change the light brightness? Occured to me there's probably a normaliser in the circuit board to limit it all to the same current, but I thought if its likely I'll get more light from a 24v input, I could buy a step up transformer from 12 to 24v to get the most out of the lights.
Click to expand...
Most LED lights will use a driver board. This driver may be a linear driver, a boost driver or a buck driver. Or a combo of all 3.

The driver is there to ensure the LEDs receive the correct voltage and amp draw. As a rule higher volts will draw less current at the driver. There may well be some variance on the efficiency of said driver. But without testing you will not know if the LEDs are brighter on 12 or 24v. Either way I’d expect the variance to be low enough that you’d struggle to see any difference by eye.
 
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