"slepax" wrote in message
m...
Hey all,
This is not really a repair question, but most of you probably have
electronic skills to answer this question.
Short description of the problem: I want to use a series of LEDs to
replace the turn signal indicator globe on my bike.
My bike battery outputs 12.5V, and currently, the bike uses a 12V/10W
globe (on each side). I intend to replace each globe by connecting 6
LEDs in a row, so that way the total voltage required for all LEDs
would be ~13.8V (a single LED consumes 2.0-2.6V, so 6x~2.3V=13.8V).
So here comes my first question. Am I assuming correctly that because
I have a total of 6 LEDs in a row (~13.8V) I
don’t need a resistor
[b:6e8628ea4d]before[/b:6e8628ea4d] the LEDs?
Next, a single globe consumes 0.83A (10W/12V=0.83A) while all the LEDs
together consume less than half (~0.05Ax6=0.30A). So here comes my
second question, do I need to put a high-power resistor in
[b:6e8628ea4d]parallel[/b:6e8628ea4d] to the LEDs to match the
current consumption compared to the globe?
Sorry it’s long, but I would appreciate you help.
Cheers,
Ronen
Yes you do still need a resistor. Measure the forward voltage drop of the
LED's you're using, and wire up a series string that will run on the worst
case lowest voltage you're likely to have, 10-12v should do it. Subtract
that voltage from the highest supply voltage you'll get, say 16v or so and
use ohms law to select a suitable resistor. You can wire up multiple
series/parallel strings to get more LEDs if you'd like to cover the lense
area with them.
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