Simple LED Head Scratcher

viperwolf

Well-Known Member
First Name
Alex
Joined
Nov 26, 2019
Threads
37
Messages
1,185
Reaction score
3,536
Location
TN US and PHilippines
Vehicle(s)
2020 Ford Everest 4x4 Titanium BI Turbo, 2015 Ford Ecosport Titanium
Occupation
Retired Military
Ok, I know Im going to seem like an idiot but I cant figure this out. I mean this is as simple as you can get, so I guess Im having one of those moments.

Superflux LED 3.1-3.5v @20ma

12-13v I need atleast a (495) 560ohm resistor for one.

I calculated I could run 3 in series most likely 4, even though the math is off. So I wired in 3 and tested with 3.1v and they were still bright. I added a 4th and still bright, then a 5th and still bright? I did not, up the voltage and left it 3.1 volts. I tried a single at 3.1v and they are equal in light. What am I missing here, this should not work. I mean 12v should not be enough to run this many in series and Im doing it with 3.1v.
So with 5 in series I have 3.1v @110ma (.11a), so the milliamps make sense but the voltage does not. I know this is going to embarrass me somehow. :giggle:

IMG_4151.jpg


IMG_4152.jpg
Sponsored

 

CO2Ranger

Well-Known Member
Joined
Apr 27, 2020
Threads
34
Messages
1,094
Reaction score
2,090
Location
Colorado
Vehicle(s)
2021 JLURD / Former: 2021 Ranger Lariat FX4
I guess the real question is: are you really in series or have you magically paralleled them somehow?
 
OP
OP
viperwolf

viperwolf

Well-Known Member
First Name
Alex
Joined
Nov 26, 2019
Threads
37
Messages
1,185
Reaction score
3,536
Location
TN US and PHilippines
Vehicle(s)
2020 Ford Everest 4x4 Titanium BI Turbo, 2015 Ford Ecosport Titanium
Occupation
Retired Military
I guess the real question is: are you really in series or have you magically paralleled them somehow?
I was going to run them in parallel but it takes up more space needing a resistor for each in line. It does act like that though. Im going to check the board again, but I even tested by breaking the circuit.
 
Last edited:

CO2Ranger

Well-Known Member
Joined
Apr 27, 2020
Threads
34
Messages
1,094
Reaction score
2,090
Location
Colorado
Vehicle(s)
2021 JLURD / Former: 2021 Ranger Lariat FX4
they are definitely in series
I was going to run them in parallel but it takes up more space needing a resistor for each in line.
Are these the 4-pin variety?
 
OP
OP
viperwolf

viperwolf

Well-Known Member
First Name
Alex
Joined
Nov 26, 2019
Threads
37
Messages
1,185
Reaction score
3,536
Location
TN US and PHilippines
Vehicle(s)
2020 Ford Everest 4x4 Titanium BI Turbo, 2015 Ford Ecosport Titanium
Occupation
Retired Military
I guess the real question is: are you really in series or have you magically paralleled them somehow?
I think you er right, looking at the diagram I have it correct, But looking at the led itself it does not match the diagram. Maybe they mislabeled the layout, bc it looks like the cathode is actually the anode in respect to the notch,If that makes sense. Then the wiring is anode-anode instead of anode-cathode for a series. Which is what you said, parallel not series.
 


OP
OP
viperwolf

viperwolf

Well-Known Member
First Name
Alex
Joined
Nov 26, 2019
Threads
37
Messages
1,185
Reaction score
3,536
Location
TN US and PHilippines
Vehicle(s)
2020 Ford Everest 4x4 Titanium BI Turbo, 2015 Ford Ecosport Titanium
Occupation
Retired Military
Im going to unsolder it, then inspect each one, bc I see the anode and cathodes separately. It does not make sense though bc the cathode is usually on the notch side. Its like the body is twisted wrong.
 

FunInTheSun

Well-Known Member
First Name
Dave
Joined
Jun 6, 2021
Threads
2
Messages
543
Reaction score
1,596
Location
South Florida
Vehicle(s)
2021 Ranger XL 4x4, STX, in Velocity Blue
Occupation
Engineer (Semi-Retired)
Vehicle Showcase
1
Ok, I know Im going to seem like an idiot but I cant figure this out. I mean this is as simple as you can get, so I guess Im having one of those moments.

Superflux LED 3.1-3.5v @20ma

12-13v I need atleast a (495) 560ohm resistor for one.

I calculated I could run 3 in series most likely 4, even though the math is off. So I wired in 3 and tested with 3.1v and they were still bright. I added a 4th and still bright, then a 5th and still bright? I did not, up the voltage and left it 3.1 volts. I tried a single at 3.1v and they are equal in light. What am I missing here, this should not work. I mean 12v should not be enough to run this many in series and Im doing it with 3.1v.
So with 5 in series I have 3.1v @110ma (.11a), so the milliamps make sense but the voltage does not. I know this is going to embarrass me somehow. :giggle:

IMG_4151.jpg


IMG_4152.jpg
Have a look at the attached pic.
You will need to run them in parallel, and to run them at 20 mA, you need a 87 ohm, 2 or 3 watt resistor. If you can't get 87 ohms, don't sweat it, 5-10% difference will not make a super noticeable difference. Don't skimp on the watts, though. Get a 2 or three watt resistor, or it will run hot and fail early. They are cheap. Maybe 25 cents.

You don't have enough voltage to run them in series.
They would end up at 2.4 volts, and will not be at full brightness.

1628648856917.png


For sourcing components at Surplus-level pricing, have a look at Marlin P. Jones.
https://www.mpja.com/

Lots of interesting stuff for cheap.
Has bunches of LED, including strips, high Watt LEDs and matching drivers for most of them, already built.
 
OP
OP
viperwolf

viperwolf

Well-Known Member
First Name
Alex
Joined
Nov 26, 2019
Threads
37
Messages
1,185
Reaction score
3,536
Location
TN US and PHilippines
Vehicle(s)
2020 Ford Everest 4x4 Titanium BI Turbo, 2015 Ford Ecosport Titanium
Occupation
Retired Military
Have a look at the attached pic.
You will need to run them in parallel, and to run them at 20 mA, you need a 87 ohm, 2 or 3 watt resistor. If you can't get 87 ohms, don't sweat it, 5-10% difference will not make a super noticeable difference. Don't skimp on the watts, though. Get a 2 or three watt resistor, or it will run hot and fail early. They are cheap. Maybe 25 cents.

You don't have enough voltage to run them in series.
They would end up at 2.4 volts, and will not be at full brightness.

1628648856917.png


For sourcing components at Surplus-level pricing, have a look at Marlin P. Jones.
https://www.mpja.com/

Lots of interesting stuff for cheap.
Has bunches of LED, including strips, high Watt LEDs and matching drivers for most of them, already built.
thank you very much.
I was not going to run 5 in series though, like I said it would/should not work. Which is why I made the thread bc it was working. That made no sense at all, but Im pretty sure I know what the problem is. However I may just keep them in parallel and use a 2 watt resistor. I have a stock of resistors but not the right one. Its not easy for me to pick any up either. I have to order and that takes some time. I have 220ohm, so i may parellel them and that will up the wattage but cut the resistance to 110. Thank You for the help.
 
OP
OP
viperwolf

viperwolf

Well-Known Member
First Name
Alex
Joined
Nov 26, 2019
Threads
37
Messages
1,185
Reaction score
3,536
Location
TN US and PHilippines
Vehicle(s)
2020 Ford Everest 4x4 Titanium BI Turbo, 2015 Ford Ecosport Titanium
Occupation
Retired Military

onobeka

Well-Known Member
Joined
Jan 20, 2021
Threads
9
Messages
389
Reaction score
1,137
Location
Romania
Vehicle(s)
2018 Ford ranger 2.2 European model
LEDs are driven in current not voltage. So you need to limit the current, otherwise you will fry them.

For longer life, subtract the voltage for as many leds from 14.4v as long as there is a surplus and divide that such that you have max 18mA. I would not go at 20mA, they will get very hot and heat burns leds.
 

oldnslow

Well-Known Member
First Name
Ken
Joined
Jan 10, 2020
Threads
0
Messages
155
Reaction score
557
Location
Sahuarita, AZ
Vehicle(s)
2020 Ranger XLT FX4 SuperCab Rapid Red
Occupation
Retired
If you are running 5 LEDs at 20mA and the power supply is showing 110mA, then you are somehow running them in parallel. If they were in series the current would be 20mA.

An engineer I used to work with said the hardest thing for a tech to get right is to light an LED. I proved him right a few times.
 
OP
OP
viperwolf

viperwolf

Well-Known Member
First Name
Alex
Joined
Nov 26, 2019
Threads
37
Messages
1,185
Reaction score
3,536
Location
TN US and PHilippines
Vehicle(s)
2020 Ford Everest 4x4 Titanium BI Turbo, 2015 Ford Ecosport Titanium
Occupation
Retired Military
If you are running 5 LEDs at 20mA and the power supply is showing 110mA, then you are somehow running them in parallel. If they were in series the current would be 20mA.

An engineer I used to work with said the hardest thing for a tech to get right is to light an LED. I proved him right a few times.
I figured out what the problem was. The notch for the cathode was actually on the anode side. the base was twisted or something. The entire pack was like that. So instead of +-+-+- and so on, it was actually parallel. The retailer I bought them from verified he had several packs that way. I should of looked at the actual contacts rather trusting the marking. I knew I could run 3 in series and possible 4, even though the math is not right for Four. It is if you consider that when running, its 13 volts.

But Im just going to keep it parallel and get the correct wattage for the resistor so I can run two rows of 5.
 
Last edited:

onobeka

Well-Known Member
Joined
Jan 20, 2021
Threads
9
Messages
389
Reaction score
1,137
Location
Romania
Vehicle(s)
2018 Ford ranger 2.2 European model
A row of 5 is too much, make it 4 in series with an 120ohm resistor. Then you can run more of this sets in parallel.
Sponsored

 
 



Top