Using LED's in place of bulbs for sidemarkers

Hello, need some help here. I plan on retrofitting about 9 LED's per sidemarker. White high-intensity LED's. The car of course has anywhere from 12-14.5 volts so would wireing them in parallel make more sense? Since they will all get the same voltage and just draw the necessary current to light them up? Part #'s from digi-key or some source would be appreciated as well on what i'll need (incl' the LED's), thanks...

Depending on the exact voltage they drop (probably around 4V), I'd wire them in series in twos or threes with a series resistor to drop the rest (the larger the difference between sum of diode forward voltages and the [varying] supply voltage, the better consistency of current through the LEDs as the supply voltage varies. So I'd only use 2 in series). Then add up such sets in parallell until you have the wanted number of LEDs. Forward current through the LEDs is typically in the 20 to 30mA range.

Resistor value = (13.5 - (N * V_forward)) / I_forward
Resistor power handling capacity = (14.5 - (N * V_forward))^2 / Resistor value

I used 13.5 as an average of supply voltage, but 14.5 (max) when calculating the power handling requirement. I also wouldn't go with absolute max forward current but rather the typical value.

/Michael

Here you go

There is a load resister you might be interested in.

I am not sure you want to reinvent the wheel, there are a good number of companies already making LED marker lights give them a look before you pull out the soldering gun.

There is one company doing it, and they want $250 for them. I own a infiniti G35 coupe, parts for this car aren't as readilly available such as a honda civic, etc.

Ekk I got a whole set for my Surburban back a few years ago for under 100 bucks from the local speed shop (tire factory in Salem oregon)


PS a Whole set was
2 turn signles
2 front marker
2 side marker
2 rear turn signles
Brake lights, and back up lights

If you want white ones, maybe. I know you can find cheap red and yellow replacements for standard car bulb sizes.