Quote:
Originally Posted by IDontKnow
I am sorry, but you are incorrect there. If wiring in parallel you can do it with only one resistor as long as the wattage is high enough as in 1/2 to 1watt resistors.
10 LED's on my flatbeds both wired in parallel with 1 resistor and been working perfectly for the last 6 months! No overheating of anything all LED's are bright and uniform in light output. Current draw? Minimal Charge the 7.2 volt 4000mAH battery about once every two to three months. The resistor size is 330ohm 1/2 watt
Will post details on the Bezels and LED's when I find it again
|
The big reason I suggest running a resistor on each LED in parallel is simple. No two LEDs are identical in their construction, which basically means the resistance of each LED, even from the same production batch, varies. Why is this a problem? Because in a parallel circuit the current will always take the path of least resistance. Or in other words, the LED that happens to have the least resistance. What happens is that LED will be subject to higher current flow then it is rated for. The more LEDs you have in your parallel circuit, the worse this problem becomes. Remember in parallel circuits that voltage stays the same to all loads. Current, however divides across them. This is also why I suggest a series circuit. In series circuits, current remains the same across all loads, regardless of each component's resistance measurement. The voltage divides.
To safely run multiple LEDs in parallel, each really should have it's own resistor, or your weakest LED will be have the most current flowing through it. Yes, you can get away with one resistor for multiple LEDs in parallel, but is not optimum for the life or performance of the LEDs.
In regards to current draw, parallel circuits are additive. It may not sound like a huge deal when you are running ten LEDs and each only draws .020 amps, but if you have 100 LEDs on a truck and trailer combo, that is suddenly a 2 amp draw! That will start to be a noticable draw on your battery. A 4000 mili amp pack will be dead in two hours with 100 LEDs, wired in parallel, alone. That does not account for any current draw from the motor, while driving. If you are one of the guys who likes to run more then 100 LEDs, it is definitely something to consider.