Question 1

if i'm to connect these leds to 12 to 13.5 volts should i connect 4 leds in series or just get a resistor for each? what value should the resistor be?

Accepted Answer

Three ways to go.  Four Led's in series, Ohms law tells me that with 13.3 volts applied you can put a 500 Ohm resistor in series with it or you can put a resistance sub box in the circuit (start on a high setting) and dial it back until a current meter reads 20 ma.  ( I always thought 30 ma but I don have the spec sheet).  For longevity error on the conservative side.  That's my story and I am sticking to it!

Question 2

Is there a data sheet available for these LEDs?

Accepted Answer

Sorry for replying you now. Forward Voltage : 3.0V-3.2V ; Forward Current: 20mA.

Question 3

Can I wire 4 3v leds in series to a 12v battery without a resistor?

Accepted Answer

Hello, Great question. The short answer is: No, its not a reliable configuration. Why: Keeping it simple. An idealized model of silicon diode requires 0.7v forward bias to begin conduction. After that, it offers no more resistance to current flow. LEDs are not signal diodes, but the principle is the same. It is a smart idea to series a few diodes with a single resistor because it wastes less power.
Here is a picture: https://www.allaboutcircuits.com/technical-articles/understanding-i-v-curves-of-non-linear-devices/.
At full brightness the drop across an LED may be about 2v, and the current should be limited to about 160mA. THE CURRENT THROUGH THE LED is the important parameter. Example calculation for estimating the resistor size would be:
(12v - N×2v)/0.160A
For something I just did, 13mA gave me the brightness I wanted, for 3 LEDs at that current the LEDs (Edgelec) were dropping 2V.
R = (12 - 3×2)/0.013 = 460ohms. The pack of Edgelec LEDs came with 470ohm resistors so I used 1 of those.
Hope this helps, just remember PN junctions are NOT linear devices!

Question 4

I bought the red and green common anode and wonder which the 430 and 470 ohm resistors are for.  Which one is for red and which for green?

Accepted Answer

The resistor included in the product is to make this led work at 12V circuit voltage.
430 ohm for Green
470 ohm for Red

ASIN	B077XBFZH9
Accepted Voltage Frequency	100 to 240 Volts and 50 Hertz to 60 Hertz
Additional Features	Assorted,Led
Beam Angle	30 degrees
Best Sellers Rank	#14,351 in Industrial & Scientific ( See Top 100 in Industrial & Scientific ) #15 in LED Lamps #2,577 in LED Bulbs
Brand	EDGELEC
Brand Name	EDGELEC
Bulb Diameter	0.2 inches
Bulb Shape Size	BT37
Color	[02] 10 Colors X 20 Pcs / 200pcs
Connectivity Technology	Normal bulb
Control Method	Touch
Controller Type	Push Button
Customer Reviews	4.6 out of 5 stars 300 Reviews
Efficiency	High Efficiency
Incandescent Equivalent Wattage	0.6 watts
Included Components	Resistors Include
Indoor Outdoor Usage	Indoor
Item Dimensions W x H	0.2"W x 1.4"H
Item Weight	290 milligrams
Light Color	Red, White
Light Source Type	LED
Light Source Wattage	0.06 watts
Light Type	LED
Manufacturer	EDGELEC
Manufacturer Part Number	ED_TC_YT05_10S
Material Type	Polycarbonate (PC)
Model Number	13
Number of Items	20
Package Quantity	200
Power Consumption	0.06 watts
Power Source	Electrical (DC)
Shape	5mm Round Top
Special Feature	Assorted, Led
Specific Uses For Product	General purpose
Style Name	[B] 5mm Constant Light
UPC	611355168453
Unit Count	200 Count
Voltage	12 volts
White Brightness	20 lumens

200pcs 10 Colors x 20pcs 5mm LED Light Emitting Diode Assorted Kit 29mm Lead Clear Round Lamp White Red Blue Green Yellow UV Bright LEDs Bulb +300pcs Resistors for DC 6-12V Lights

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