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Old 09-17-2012, 03:42 PM   #1
AEA737
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Default 12V LEDīs on a 4S Lipo

Hi guys.

Iīve been flying my hexacopter with a 3S Lipo and some 12V LEDīs. Now I have moved to a 4S Lipo for better performance but Iīm afraid the extra voltage might fry my LEDīs.

Is there an easy way to step down voltage to 12V? Or is it better to plug a small 3S Lipo to just lit the LEDīs?

Thanks for your help.

Javier
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Last edited by AEA737; 09-17-2012 at 03:48 PM.. Reason: Typo
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Old 09-17-2012, 04:11 PM   #2
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Can always get a regulator.
Also, I believe the CC BEC Pro can go up to 12V. Check that out.


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Old 09-17-2012, 08:31 PM   #3
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Just tap off of 3cells from your balance lead on your battery. You should be able to find a female a 4 cell balance connector pretty easy on one of the online hobby shops and then just wire it for 3 of the cells so you can easily plug and unplug your LED setup to your battery.
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Old 09-18-2012, 02:55 AM   #4
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Quote:
Originally Posted by heraldo View Post
Can always get a regulator.
Also, I believe the CC BEC Pro can go up to 12V. Check that out.
Thanks. Iīve been looking at some BECīs but they were all outputting 5-6V. I see that the CC BEC outputs 9V, maybe thatīs enough.

Javier
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Old 09-18-2012, 03:03 AM   #5
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Quote:
Originally Posted by Timtreo View Post
Just tap off of 3cells from your balance lead on your battery. You should be able to find a female a 4 cell balance connector pretty easy on one of the online hobby shops and then just wire it for 3 of the cells so you can easily plug and unplug your LED setup to your battery.
Thanks. How unbalanced can that unused cell be after lighting say 40-50 LEDīs for a 10 min flight? Whatīs the power consumption of 50 LEDīs?

If I tap 3 wires from my 4S Lipo I end up with 3 positive wires from each cell and the common negative. How do you attach that to the LED strip? I have never worked with balance plug s and donīt want to fry the Lipo.

Thanks for your info.

Javier
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Old 09-18-2012, 03:55 AM   #6
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I'm powering Turnigy LEDs with straight 4S LiPo, working pretty well for now (about 5 flights, 10-15 mins per flight)
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Old 09-18-2012, 08:41 AM   #7
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Quote:
Thanks. How unbalanced can that unused cell be after lighting say 40-50 LEDīs for a 10 min flight? Whatīs the power consumption of 50 LEDīs?

If I tap 3 wires from my 4S Lipo I end up with 3 positive wires from each cell and the common negative. How do you attach that to the LED strip? I have never worked with balance plug s and donīt want to fry the Lipo.
All good questions, honestly I use a seperate 2 cell to power my airframe LEDs but I know some people tap off of the balance plug. I would think the cells should all drain pretty equally from still being connected to the ESC, but not sure. One of the balance pins in the connector has to be negative I would think to make the common ground connection. I am looking into getting an LED RGB controller and RGB strips and redoing my whole setup so I hope someone can shed some more light on the balance plug tapping myself.
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Old 09-19-2012, 04:48 AM   #8
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Anyone? I did find these... http://www.headsuprc.com/servlet/the...sh-XH-4/Detail
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Old 09-20-2012, 12:10 PM   #9
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For a 4s plug you can use one of these:

http://www.bphobbies.com/view.asp?id=B3795268&pid=B3805292

It will unbalance your pack just a bit. 60 leds will draw 400ma so it will barely affect your flight time, maybe 30 seconds shorter.

Or you could use a small 3s pack like this one:

http://www.bphobbies.com/view.asp?id=A2416229&pid=F3273871

I use a 3s 370mah lipo for the lights on my 450 and barely notice any weight difference in flight.
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Old 09-20-2012, 01:55 PM   #10
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i am no EE, i believe you need to add a resistor to limit the amps getting to the LEDs. then you can use the main battery.
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Old 09-25-2012, 09:19 AM   #11
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Quote:
Originally Posted by Crashtestheli View Post
i am no EE, i believe you need to add a resistor to limit the amps getting to the LEDs. then you can use the main battery.
But this resistor must burn some power. And it is different for each LED strip you use (number of LEDs, colour?).

As long as the LEDs have no other connection (RC switch) to RX and ESC you don't need to connect to Minus(black), you can also use the higher 3 cells. Even some LEDs on the lower 3 cells and the other on the high 3 cells. Gives a more even discharge.

RK
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Old 10-30-2012, 04:43 AM   #12
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Quote:
Originally Posted by robi1kenobi View Post
I'm powering Turnigy LEDs with straight 4S LiPo, working pretty well for now (about 5 flights, 10-15 mins per flight)
Thanks Robi. I tried the LEDīs also with 4S until I install the CC Bec Pro and they work perfect! No problems so far.

Javier
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Old 11-02-2012, 12:32 PM   #13
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The 12V LED strips are designed for automotive use. a car with the engine running can be up to 14.5V, that is pretty close to the 14.8V nominal of a 4S LiPo.

Normally the color matters to the value of a dropping resistor. In this case the strip already has the correct dropping resistor for up to 14.5V built in at the LEDs. This means that regardless of the color you just need a dropping resistor to go from 16.8V (Fully charged LiPo) to 14V. To get the right resistor you just need to know how much current your LED setup pulls and plug the values into the calculator at http://led.linear1.org/1led.wiz.

Use 16.8V as the source, 12.6V as the LED forward voltage, and then enter the current for the whole led strip.

You can either measure the current of your strips or go to where you bought them and see if they say what the current draw is.
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Old 12-25-2013, 09:38 PM   #14
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Use 3 diodes in series on the main power wire to the LED strip and it will be fine. More diodes if you want the lites dimmer . Heat shrink a couple different variations and just plug N Play.
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