Hey guys, i have a truck with traxxas velineon vxl 6s ESC and i have spares of traxxas LEDS which are 3v.
Is there any way to power them from the ESC accessory port? There isn`t any info how many volts it support.
If i can`t give me some ideas please

According to this page: https://traxxas.com/products/parts/3485T, the BEC output is 6V. Easy to check with a cheap multimeter, but two LEDs in series should be fine. You can run lots of series pairs, since it's good for a few amps (each series pair would be 20-30mA).

Alternatively, hunt down an LED controller that will give you lots more options.

What about current limiting resistors?

Always an option, just adds a little complexity (needs some fine soldering skills). Also possible to use current limiting drivers, which are commonly used inside LED control modules.

So, a worked example:

• 6V voltage source, 3V LED, assume typical forward current of 20mA
• You need a 3V drop across your resistor, leaving 3V across your LED.
• Resistance (R) = Voltage (V) divided by Current (I)
• R = 3 / 0.02
• R = 150ohm

You can extrapolate this approach for any voltage and any number of LEDs in series. Eg:

• 12V voltage source, 3 x 2V LEDs in series
• So, 6V across the LEDs, needing 6V to be across your resistor
• 20mA is a very common forward current for readily available LEDs (* see note below)
• So, R = 6 / .02
• R = 300ohm

* There are single LEDs that operate at much lower currents, and LEDs that operate at much higher currents, but 20mA is pretty common. Always best to check the datasheet (if available)

** Bonus: different colours in LEDs are produced by different materials in the LED; the different materials result in different forward voltages. 1.8-2.0V is pretty typical for red, 3.2V is common for blue, Different wavelengths of green can be anywhere between 2V and 3+V. White is not actually a colour . Ok - white LEDs use slightly different technology, leveraging phosphorous material to simultaneously emit a broad spectrum of wavelengths. A lot of white LEDs operate in the 3V range.

LEDs actually operate best in a "current controlled" manner, rather than a "voltage controlled" one, but the latter is easier with a simple resistor. An extensive range of off-the-shelf current controlled drivers exist for different current ratings. This makes it trivial to put a dozen LEDs in series and stick 48V across it and have it work reliably (assuming the power dissipated by the driver is within spec). An example of a simple 20mA driver is: https://www.onsemi.com/products/powe...ivers/nsi45020

FWIW, you'll be able to see this at the nats this weekend, I've done an adaptation of my LM module so it can use off-the-shelf LEDs that are common with drift setups. Three ports each with a current limiting driver, so it doesn't matter what LED you plug in:

It is not an option, with LEDS it is a must. (or any other current limiter electronics)

But from what I see you need the Traxxas 8028 module to regulate the LED current.

Not sure which LED's you have but if you know the current per LED you can easily calculate a needed resistor for it. When powering by the BEC I would not put 2 in serie for 6v because there will be no voltage left to regulate the current, so each LED must have its own resistor. Google to a LED calculator and you will find plenty to calculate the resistor. But basically it is (BEC voltage - LED voltage) / LED current. In this case it is (6-3)/current.

Hello and thanks for the answers.
The idea is to power these https://traxxas.com/products/parts/8897 from the power accessory port of the ESC.
Maybe i should get this https://traxxas.com/products/parts/6588 and wired it somehow to the accessory port?

Nice 3v Module but the output connectors do not match the connectors of the LEDS, the 8028 module does! But it looks like that 8028 module needs that 3v power supply to be powered, It is very unclear!

Because white LED's are 3v I can conclude there are in total 8 parallel. A standard LED needs about 20mA
OK, 3v LED's on 6v needs a 3v drop, R=U/I (ohms law) so 3v/0.16 = 18 ohm.
You need a serial resistor of 18 ohm.

To be honset, Traxxas is very unclear with giving enough information about their modules.

If you have an adjustable lab power supply (or know someone) you could connect the LED's to it and set it to 4v -0A and slowly raise the current to find out the needed current for decent light.

maybe i could try to rework the connectors and cables to fit the power socket

For clarity, it's not a good idea to run LEDs in parallel off a single resistor, as explained here: https://electronics.stackexchange.co...ds-in-parallel

Reworking connectors can be viable, but working with the small connectors can be fiddly. It might be easier to buy some ready-made cables and cut/splice the wires rather than crimp new connectors.

My idea as well but it is more often done than you think like with these Traxxas lights. But the topicstarter is a noob on electronics so I do not think you have to make it harder for him.