Power for LED lights on 6S battery

[ProPilotWannaBe]

Anybody have any suggestions on how to provide power to my LEDs with a 6S battery? LEDs have a 12V input, and I know I can go with a BEC for this, but I'm thinking cheaper and lighter, and someone told me that I can easily get a 12V DC output transistor from Home Depot or someplace like that. Has anyone done this?

 

[Efliernz]

Cheaper and lighter... I thought a plug n play HK $4.50 12v ubec would fit nicely! How much are your 6S worth?

Sorry - sometimes the hassle of creative wiring isn't worth it but if you are determined... it's dead easy. Have your lights in pairs and run them in series. 12v + 12v = 24v

Pete

 

[ProPilotWannaBe]

Pete, do you mean in series? If I did them in parallel, each strip would still get 12V.

BTW, what I did today was pick up a $1.99 12V regulator (something two people recommended), and I am actually in the process of wiring them up now. I've already confirmed the regulator's output voltage, and now I'm connecting to the LEDs themselves. I'll let you know.

 

[ProPilotWannaBe]

It worked. The 12V regulator is 10mm by 10mm by 4mm. On the downside, for $1.99 what you get is 12V but only up to ~400mA (about 1m of LEDs). So I may have to go with a 12V UBEC, or try your idea of wiring them in series.
(FYI, the S800 only runs on 6S, so can't switch away from those.)

 

[Maverick]

Anybody have any suggestions on how to provide power to my LEDs with a 6S battery? LEDs have a 12V input, and I know I can go with a BEC for this, but I'm thinking cheaper and lighter, and someone told me that I can easily get a 12V DC output transistor from Home Depot or someplace like that. Has anyone done this?

You could try something like this, using your 6S's balance plug. It may discharge your lipo's cells unevenly, but not enough to make a huge difference.

Make sure and tap off the 3S point, and the GND.

View attachment 12008

Maverick.

 

[Efliernz]

Pete, do you mean in series? If I did them in parallel, each strip would still get 12V.

BTW, what I did today was pick up a $1.99 12V regulator (something two people recommended), and I am actually in the process of wiring them up now. I've already confirmed the regulator's output voltage, and now I'm connecting to the LEDs themselves. I'll let you know.

Yup Series... I quickly realised what I had typed by the time I walked to the other end of the house (rushed back and corrected it) - but you clicked "read" first

 

[Dlavila]

It worked. The 12V regulator is 10mm by 10mm by 4mm. On the downside, for $1.99 what you get is 12V but only up to ~400mA (about 1m of LEDs). So I may have to go with a 12V UBEC, or try your idea of wiring them in series.
(FYI, the S800 only runs on 6S, so can't switch away from those.)

If the voltage regulator is a linear regulator this solution is not efficient since the regulator dissipates (V_battery-Vleds)*I_leds, which means that you waste 50% of the power

 

[ProPilotWannaBe]

Maverick, I was thinking exactly the same thing as I was out driving today doing errands. Since I actually have two banks of LEDs, I can tap one off from Gnd to pin 4, and another from pin 4 to pin 7. That would even out the cells, even though I agree it wouldn't make a big difference either way. I think I'm gonna try that.

Dlavila, I did not know that. Thanks for explaining.

 

[Maverick]

Maverick, I was thinking exactly the same thing as I was out driving today doing errands. Since I actually have two banks of LEDs, I can tap one off from Gnd to pin 4, and another from pin 4 to pin 7. That would even out the cells, even though I agree it wouldn't make a big difference either way. I think I'm gonna try that.

Dlavila, I did not know that. Thanks for explaining.

I'm not sure if that will work - you only have one GND per balance lead. From pin 4 to pin 7 is two positives. You will have to tap the balance plugs on BOTH lipos, to get a second supply.

The only 12v point on any balance plug, is at the 3S pin - fourth pin from the end, including GND, which is the first one.

Maverick.

 

[Efliernz]

I'm not sure if that will work - you only have one GND per balance lead. From pin 4 to pin 7 is two positives. You will have to tap the balance plugs on BOTH lipos, to get a second supply.

The only 12v point on any balance plug, is at the 3S pin - fourth pin from the end, including GND, which is the first one.

Maverick.

"the only 3S is gnd-pin 4" isnt quite right. 3S / 12v is a voltage difference between two pins. Eg. Approx 4v between Gnd/pin1 and pin 2. Another 4v between pin 2 and pin 3 etc.
So you will have approx 12v difference between 1 and 4, 2 and 5, 3 and 6, 4 and 7. Just don't common the earth/neg of the light wiring or it will all vaporise instantly and you have to start again!

Pete

 

[Maverick]

I didn't know that Pete. So where do you take the second GND from, if you tap a second supply from the same balance plug...?

Maverick.

 

[Bartman]

i'm actually doing this with my current heli, running 6S to the ESC's and 3S from the balance tap to the FC, Rx, and LED's. DO NOT pull 3S from cells 1-3, any common grounds to the 6S will deliver 6S to your 3S circuit and deliver a kill shot. Instead, pull 3S from cells 4, 5, and 6 as that is the safer way to do it. If you need lower V for the RX or FC, use a regulator.

 

[ProPilotWannaBe]

"the only 3S is gnd-pin 4" isnt quite right. 3S / 12v is a voltage difference between two pins. Eg. Approx 4v between Gnd/pin1 and pin 2. Another 4v between pin 2 and pin 3 etc.
So you will have approx 12v difference between 1 and 4, 2 and 5, 3 and 6, 4 and 7. Just don't common the earth/neg of the light wiring or it will all vaporise instantly and you have to start again!

Pete is totally correct. Voltage is a differential. And as he pointed out, as long as you don't common "ground" them, you're fine. In my case, I'm hooking up to LEDs which don't have a "ground", per sae, but just a '+' and '-'.
I would never try this concept on anything that does truly ground itself, such as a receiver, or the FC, or any of the other components that connect to eachother. Those all have common ground running through them.

Maverick, to answer your question, I'll connect the '-' of the first bank of LEDs to the Gnd wire of the LiPo, and the '+' to the 3S wire, thus getting the ~12V. Then for the second bank of LEDs I'll connect the '-' to the 3S wire, and the '+' to the 6S wire, thus getting another ~12V. Then effectively I'm leveling the load on both halves of the battery.

 

[ProPilotWannaBe]

i'm actually doing this with my current heli, running 6S to the ESC's and 3S from the balance tap to the FC, Rx, and LED's. DO NOT pull 3S from cells 1-3, any common grounds to the 6S will deliver 6S to your 3S circuit and deliver a kill shot. Instead, pull 3S from cells 4, 5, and 6 as that is the safer way to do it. If you need lower V for the RX or FC, use a regulator.

Bart, could you explain what you're saying again? I'm confused by it. The black lead on the balance tap is the Gnd pin, so if you need 3S for your FC/Rx, it seems to me you should be using black lead and the 3S pin.

 

[Maverick]

Pete is totally correct. Voltage is a differential. And as he pointed out, as long as you don't common "ground" them, you're fine. In my case, I'm hooking up to LEDs which don't have a "ground", per sae, but just a '+' and '-'.
I would never try this concept on anything that does truly ground itself, such as a receiver, or the FC, or any of the other components that connect to eachother. Those all have common ground running through them.

Maverick, to answer your question, I'll connect the '-' of the first bank of LEDs to the Gnd wire of the LiPo, and the '+' to the 3S wire, thus getting the ~12V. Then for the second bank of LEDs I'll connect the '-' to the 3S wire, and the '+' to the 6S wire, thus getting another ~12V. Then effectively I'm leveling the load on both halves of the battery.

Ahhh! That's good to know - I always thought you had to use the black lead as the '-'

Thanks!

Maverick.

 

[Bartman]

Bart, could you explain what you're saying again? I'm confused by it. The black lead on the balance tap is the Gnd pin, so if you need 3S for your FC/Rx, it seems to me you should be using black lead and the 3S pin.

You could pull 3S power using cells 1, 2, and 3 but what happens is that a common ground between your 3S circuit and a 6S circuit can result in 6S power going through your 3S circuit. To prevent this, cells 4, 5, and 6 should be used. I think you actually said this in an earlier post, sorry if I mucked things up by repeating it and then confusing everyone!

I originally tried to pull 3S power and 2S (cells 5 and 6) power from the same balancing tap but the 3S (using cells 1, 2, and 3) did what I described above and fried my harness. I've simplified things and so I'm currently just pulling 3S from 4, 5, and 6 with a regulator putting 5V into the receiver.

Keep in mind the balance taps are light gauge wire and using them to supply 3S power renders them useable for only small current amounts. They're limited to four or five amps at 3.7 volts so at 11.1 it's 1.5 amps. Electrics aren't my forte so some confirmation would be welcome.

Bart