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Help! How can I power 2 1w LEDs with a 3.7V e-flite battery? Answered

I am trying to wire/solder up two LEDs to put into a visor for a costume. When I tried the battery with 2 LEDs they burnt out. Since the two lights will be right in front of my eyes and the battery near my temple, I do not want anything getting too hot. I have tried to use online LED calculators but I can't understand the results. Thank you in advance for any help.
Here are the specs on the battery:

Type:  LiPo
Capacity:  120mAh
Voltage:  3.7V
Maximum Continuous Discharge :  14C
Maximum Continuous Current :  1.7A

and here are the specs on the LED:

Luminous flux: red :40-50Lm
Wave Length: Red :620-625nm
Forward Voltage: Red :2.2-2.6V
LED Emitter: 1W
Emitted Color : Red
DC Forward Currect (IF) : 300~350 mA




5 years ago

another question I have for you is how long do you need this to be turned on. Your batter is 150mAh according to your picture, or 120mAh according to your text. That means if the device connected to the battery draws 120mAh or 150mAh (whichever it actually is for your battery) your battery will be dead in an hour. If your LED's are truly drawing the minimum 300mA each, in parallel the will draw 600mA combined you are 4 times that 150mA which means your battery will be dead in 15 minutes or less.


Answer 5 years ago

I will be running the lights for about 10-20 sec intervals every couple of minutes for however long they last. I have two of the same battery so I can swap them out if one gets low, plus they are rechargeable.

Lets go with whats printed on the battery, the 150mAh. I will try and find two 4.7 ohm 1w resistors to wire in and try it out. Thanks for the help so far


5 years ago

When you go to the LED calculator here


your source voltage is 3.7 enter that into source voltage field

Your diode fwd volatge is 2.2-2.6v I would put in 2.4 in the diode forward voltage field

your fwd current is 300 to 350 I would put 325 in the diode forward current field

put 2 in the number of LED's in your array field

click design my array

At the bottom of the page will be a diagram showing you how to wire the circuit.


Answer 5 years ago

Each of the two LED's would have its own wire going from the + side of the LED to the + side of the battery. Also each will have it's own wire going from the - side of the LED to it's own 3.9 ohm resistor. Then a wire from the resistor to the - side of the battery.