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Way to lower power (system 12V) to power LED?

T

thomas3120

Member
Hello,
Was wondering what was the best way to lower the power on a 12VDC system to power a LED?
Linear/Switching Voltage regulator, other method...?

With the new LED plug in lights now on the market for bow/stern conventional bulbs, wondering what the manufacturers use to lower power for the LEDs?

thomas
 
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kimcrwbr1 said:
I think your mistaken the LEDs are just drop in replacements and actually use 12v DC and draw a little higher amps than standard bulbs. Do you have a link to the bulbs you are talking about? There should be a description on power requirements for the lights.
Click to expand...

Thanks for the reply Kimcrwbr1,
Sorry for the misunderstanding but meant to say, for example a single LED (one that requires 2-3.3VDC, etc..) or a LED you can get at the rat shack.

The reference to the drop in replacement ones was wondering what they use on their small pcbs to drop the power down (unless those LEDs are 12V powered..?)

Also from your reply:
LEDs are just drop in replacements and actually use 12v DC and draw a little higher amps than standard bulbs.
Click to expand...
Hmm, interesting...thought the drop in replacement LED ones draw less amps than the standard bulbs.

t
 
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I cannot definitively answer the first part of your question, but LED's do draw very substantially less amps than conventional filament bulbs. If I recall correctly, the typical LED draws somewhere around 10 to 300 milliamps. Most LED's are at the lower end of that range.

Each LED is manufactured for a specific voltage, so given their very low draw, I suspect there is a built in resistor that steps down the 12V input voltage down to voltage needed by the LED.
 
Sorry for the misunderstanding but meant to say, for example a single LED (one that requires 2-3.3VDC, etc..) or a LED you can get at the rat shack.
Click to expand...

Ayuh,.... 6, 2 volt leds, or 4, 3 volt leds wired in series uses 12 volts,...
 
plain LED's don't like to be driven by voltage they are current driven. What you have to do is add a series resistor to the LED. Value is calculated by supply voltage minus forward bias voltage of the LED (usually 1.6 to 2.5V depending on type) divided by the nominal current as specified in the datasheet.
Better systems or systems with LED's in series use current sources as that keeps the current constant but if you only want to power 1 LED the series resistor works just fine. Just use the real nominal battery voltage (13.2V) to calculate the resistor and not the 12V.

Unfortunately bondos math doesn't work here and would kill the LED's in no time especially over temperature.
 
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