SMD LED 3014 powering with 18650 cell

Thread Starter

prerakk

Joined May 21, 2015
36
Hey friends i am trying to make emergency light using couple of spare SMD LED 3014 that i found from non working tube light.

I already soldered the leds in parallel, but the problem is , its getting hot after a few minutes of workin.

What modification i can do so that it extend the LED life and prevent it from shortin.


Thanks in advance ❤
 

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Last edited:

Audioguru again

Joined Oct 21, 2019
3,173
One 18650 battery cell is 4.2V when fully charged.
The LEDs you have that appear yellow are white and each one has a forward voltage of 3.0V to 3.5V. Then when two LEDs are in series they need at least 6V that you do not have and they will not produce light.

Maybe you mean that you connected two LEDs in parallel? Then the 4.2V from the battery will quickly burn them out. Maybe your battery cell was not fully charged?
LEDs always need a series resistor or circuit to limit their current.
 

sghioto

Joined Dec 31, 2017
2,363
From the photo I see 9 LEDs in parallel with no current limiting resistor.
Try adding a 5.6 ohm 1/2 watt resistor in series (or in line) with the green or blue lead from the battery.
 
Last edited:

Tonyr1084

Joined Sep 24, 2015
5,969
Looks to me like it was intended to be a series of three LED's in series paralleled with two more sets of three. At this junction it looks like there may have at one time been limiting resistors.
1621781580411.png
 

Thread Starter

prerakk

Joined May 21, 2015
36
One 18650 battery cell is 4.2V when fully charged.
The LEDs you have that appear yellow are white and each one has a forward voltage of 3.0V to 3.5V. Then when two LEDs are in series they need at least 6V that you do not have and they will not produce light.

Maybe you mean that you connected two LEDs in parallel? Then the 4.2V from the battery will quickly burn them out. Maybe your battery cell was not fully charged?
LEDs always need a series resistor or circuit to limit their current.
From the photo I see 9 LEDs in parallel with no current limiting resistor.
Try adding a 5.6 ohm 1/2 watt resistor in series (or in line) with the green or blue lead from the battery.
Looks to me like it was intended to be a series of three LED's in series paralleled with two more sets of three. At this junction it looks like there may have at one time been limiting resistors.
View attachment 239392
yes i didnt had spare circuit board and wanted to turn it from12v to 3.7 volt so i soldered all in parralel by removing the resistor
 

Thread Starter

prerakk

Joined May 21, 2015
36
ive decided to turn it into 3S (3 18650 cell ) to 12v smd led board . i wish to use this light for forest walks as i cant find something similar in my local market.

for powerpack i am going to use 3 nos. of 18650 soldered on 3S BMS board (img attached) .
for light i am using 48 SMD5050 led board (pic attached).

My concern is how much time is it going to work with Full/High Brightness ?
for checking it , i have charged all the 3 batteries to full , connected it in series and pluged the board.
the results before and after lighting for 15mins were :

each cell before charge was around 4.07v and after it was around 3.8v
amp before was 0.8amps and after it was 0.67amps.

Kindly guide me the right way to build it and how long it can be used on full brightness with.or if theres anything else i need to use with this circuit.

thank you so much for reading and replying
 

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Audioguru again

Joined Oct 21, 2019
3,173
4.07V is no where near a full charge. 3.8V is half a charge with the voltage dropping quickly.
Your "protection" board is not a battery charger that must detect the dropping of charging current that causes the charger to stop charging.
 

Thread Starter

prerakk

Joined May 21, 2015
36
4.07V is no where near a full charge. 3.8V is half a charge with the voltage dropping quickly.
Your "protection" board is not a battery charger that must detect the dropping of charging current that causes the charger to stop charging.

Thanks !

I have charged each cell individually using tp4056 . what can be done for voltage droppin quickly

PS i have ordered the 3S board online so it will take fee days to arrive to me
 
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