5V LEDs and 7.4V BEC - can I make it work?

[Barmaleus]

Hi everyone!

Here is the story:
1. I have Kraton 6s v6, BEC at 7.4V
2. Got this front/rear LED setup at AliExpress, which is rated at 5V (duh, did not pay attention to it during order):
https://www.aliexpress.com/item/1005006641320865.html
3. Additionally, got this LED controller to turn the LEDs on/off:
https://www.aliexpress.com/item/1005006808011217.html

My knowledge of the electronics is very basic, but from what I understand supplying 7.4V to this 5V setup will burn the LEDs or drastically reduce their life.

Is there something I can do to make it work together? Any advice appreciated. Thank you!

 

[King blitz]

I run my lights off a separate small 2s lipo .it's solves any headaches .other than having to charge the small lipos I don't worry about nothing.

 

[Barmaleus]

I run my lights off a separate small 2s lipo .it's solves any headaches .other than having to charge the small lipos I don't worry about nothing.

I see. Hm, 2s LiPo is still 7.4 volts. Or you have some very specific one that provides 5V?

 

[King blitz]

On some of my rigs just one very tiny 2s 360 mah 30c is all I need to run basic front and rear lights .on some of my other rigs where I have under glow and multiple sets of lights running I run two lipos .

 

[RCbuzz]

You just want small dc-dc converter. Let me get you a link.

 

[RCbuzz]

This one brings it down to 5v:

https://www.amazon.com/Regulator-Reducer-Converter-Aircraft-MP1584EN/dp/B0B779ZYN1/

This one is variable:
https://www.amazon.com/HiLetgo-Super-Converter-Module-Adjustable/dp/B00LODGDYE/

Lots of models, reviews, etc.

 

[King blitz]

What I was suggesting was not to plug the light set into a channel on your receiver. Run a separate power source so your not messing around with your BEC. If the lipo I showed you isn't sufficient enough for whatever your running then get a larger lipo.or multiple lipos like I do .the ones I use are so small and weight nothing.and I Velcro them in the chassis..it's a no brainer and it's simple

 

[King blitz]

Not sure why you would need a converter I can run one simple light set off of that little 7.4 volts lipo and never had a light set burn out .

 

[RCbuzz]

Although I have not tried this yet I planned on installing these on my led lights to protect the BEC circuit from short circuit (crash, wire pinch, etc).

https://www.amazon.com/20PCS-1206-Resettable-Fuse-PPTC/dp/B0B9H2FSZJ/

 

[King blitz]

Years ago I used to run light sets off a 9volt Energizer battery and never had a problem running a cheap China light set.

 

[King blitz]

Although I have not tried this yet I planned on installing these on my led lights to protect the BEC circuit from short circuit (crash, wire pinch, etc).

https://www.amazon.com/20PCS-1206-Resettable-Fuse-PPTC/dp/B0B9H2FSZJ/

Not needed .when you can run a separate power source.

 

[Garcbomber]

+2-3Volts is no problem for an LED if it can breathe. I’ve been running 6V LED strips on my infraction for years on a 3S balance plug.

 

[King blitz]

Many RC led light sets are already protected by a resistor in the bulb .that limits the amount of current to the bulb. And honestly in all my years in the hobby ,I've never even payed attention to it.i just grabb a light set and plug it to a lipo and that's it..never had issues when you start going into some real complex light systems then I would definitely pay attention to how it's organized and that it has the right amount of voltage.but not for a simple plug and play light set.

 

[RCbuzz]

Hi everyone!

Here is the story:
1. I have Kraton 6s v6, BEC at 7.4V
2. Got this front/rear LED setup at AliExpress, which is rated at 5V (duh, did not pay attention to it during order):
https://www.aliexpress.com/item/1005006641320865.html
3. Additionally, got this LED controller to turn the LEDs on/off:
https://www.aliexpress.com/item/1005006808011217.html

My knowledge of the electronics is very basic, but from what I understand supplying 7.4V to this 5V setup will burn the LEDs or drastically reduce their life.

Is there something I can do to make it work together? Any advice appreciated. Thank you!

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+2-3Volts is no problem for an LED if it can breathe. I’ve been running 6V LED strips on my infraction for years on a 3S balance plug.

I run all my LED's off the BEC, even on our 3S Arrma's with the BLX100 ESC's. No issues, one dicey crash that almost shorted something . My LED's are lower power though (less than an amp).

As for "higher than rated voltage" on LED's and them surviving.. That really all depends on the manufacturer of the kit. I have noticed a few of them are pretty conservative in their choice of resistor. Perhaps they know the typical RC'er might have a higher BEC voltage and do it anyways?

Consider that LED's do not regulate current well (or at all) past their rated voltage. Without the resistor the LED current will go to the moon when you exceed the rated voltage and die.

Check out these LED Resistor calculators, it will help show the relationship using Ohms Law:
https://www.allaboutcircuits.com/tools/led-resistor-calculator/
https://www.digikey.com/en/resource...ors/conversion-calculator-led-series-resistor

For example: 5V LED with a forward voltage of 3.6V(typical blue/white LED), and a forward current of 300mA(that is on the higher side, say a small light bar). Your resistor value is 5Ohms.

Now say, well what am I doing to the LED's if I pump it with 7.4volts?

5Ohms = 7.4V - 3.6V / (AMPS?)
Amps = 7.4V - 3.6V / 5Ohms
= .76Amps (versus the .30A the LED was rated for).

So, the current goes way up and the LED wont last as long. It does show how important the resistor is in the circuit though.

Hope that helped a little.

 

[RCbuzz]

Not needed .when you can run a separate power source.

For those super power LED systems it seems like a separate source would be good. I just really don't want to deal with a separate battery

 

[King blitz]

For those super power LED systems it seems like a separate source would be good. I just really don't want to deal with a separate battery

I hear ya , reason why I do is because my servos suck a lot of juice and I need that BEC to power it.

 

[FPVkabina]

Hi everyone!

Here is the story:
1. I have Kraton 6s v6, BEC at 7.4V
2. Got this front/rear LED setup at AliExpress, which is rated at 5V (duh, did not pay attention to it during order):
https://www.aliexpress.com/item/1005006641320865.html
3. Additionally, got this LED controller to turn the LEDs on/off:
https://www.aliexpress.com/item/1005006808011217.html

My knowledge of the electronics is very basic, but from what I understand supplying 7.4V to this 5V setup will burn the LEDs or drastically reduce their life.

Is there something I can do to make it work together? Any advice appreciated. Thank you!

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You simply need a Bluesky 5v ubec.

Just make sure the 5v is heading towards your light/s.

 

[Dan B.]

What I was suggesting was not to plug the light set into a channel on your receiver. Run a separate power source so your not messing around with your BEC. If the lipo I showed you isn't sufficient enough for whatever your running then get a larger lipo.or multiple lipos like I do .the ones I use are so small and weight nothing.and I Velcro them in the chassis..it's a no brainer and it's simple

Read the OP. He needs lower voltage, not higher. He needs a 5v supply, not 7.4 or higher.

+2-3Volts is no problem for an LED if it can breathe. I’ve been running 6V LED strips on my infraction for years on a 3S balance plug.

I agree, me too. I’m running 5 or 6 volt lights on 8.4v BEC output on several rigs for years with no issues at all.

For those super power LED systems it seems like a separate source would be good. I just really don't want to deal with a separate battery

Like @Garcbomber said, I doubt the extra couple of volts would matter to the lights as long as they would get good airflow around them. I’d suspect that higher voltage may be a problem for your light controller. If it were me, I’d just pick up a new 7.4 or 8.4 volt capable light controller for about $8.00
https://www.amazon.com/Remote-Contr...prefix=rc+light+controlle,aps,120&sr=8-6&th=1
If you have the specs on your controller and the one you already have can support the higher voltage (I suspect it probably can) then I would just plug the setup into the receiver and never look back.

 

[King blitz]

Read the OP. He needs lower voltage, not higher. He needs a 5v supply, not 7.4 or higher.

I agree, me too. I’m running 5 or 6 volt lights on 8.4v BEC output on several rigs for years with no issues at all.

Like @Garcbomber said, I doubt the extra couple of volts would matter to the lights as long as they would get good airflow around them. I’d suspect that higher voltage may be a problem for your light controller. If it were me, I’d just pick up a new 7.4 or 8.4 volt capable light controller for about $8.00
https://www.amazon.com/Remote-Controlled-Electronic-Switch-Relay/dp/B08FLZXSD7/ref=sr_1_6?crid=56B0S2V5S4P9&dib=eyJ2IjoiMSJ9.xAgQMQMFLtZ0W5obPD5XT3eUJs7TLnMuWc4CRtI59p5gzQxjRELYL6ZbgH2jBfQIgif9iXU0MAQS9rqb6qNBqBNsW2XdNingA4DT6jagBaLxFCQ3OBuTcXckaS9pfK8R3e-MYC1My7BOBQ9obnNEZ2wI7ON3dvWkKHyfzNiXNrIfCSktiFWjdub4RdmRuTg8KWcEvmSP3PHPnzt-op69m47ox68SXfG0047syIhzqWymUUEM-E_LPPbK3KQAvYl2UR7Jp0yDQaadVEk2G-qXmKWG9aybPgPb9spO9jeEk_bj4kWYYWlx3hSAycy-T-BU_SofuyjDr05Erf-29aezxlR2NtpSfE9nd7Stl50opMJmpugdxpJK4RY8EDvUY62IDgXkslt3cgcNYN0b3h8Q5EHQheMDxVeFK__5ny6iQmFSrXyY4ggPQ-SrNoAXX7N9.rXaRcJiIfBHLP6X5qVZ1HTXjfjeAKUwx8u51WjVB5m0&dib_tag=se&keywords=RC+light+controller&qid=1742301117&sprefix=rc+light+controlle,aps,120&sr=8-6&th=1
If you have the specs on your controller and the one you already have can support the higher voltage (I suspect it probably can) then I would just plug the setup into the receiver and never look back.

I clearly read it perfectly..lol he can get the 5 volts from the 7.4 lipo I showed in the PIC...Mr Dan your a day late

 

[Barmaleus]

Dear sirs, thank you for all the input! Need to digest it!