6s vs 12s

[veloflier]

Would a 12s setup be better to run a 600 sized scale bird? Could a 600 sized heli even run a 6s setup?

[Andy01]

I am sure you could run a scale 600 heli, but the amps will be twice as high as a 12s heli, so there is likely to be more heat, and it will be less efficient, and the flights will be shorter.

Colin

[veloflier]

I have heard most people flying 12s, but seen the random 6s. This is my first larger heli. I have a 450, and a 500. Figured it was time for something bigger. That and I am leaning more towards scale flight. Figured 12S would have more power.

[Commodore8888]

Only time I run 6s anymore is for superlow headspeeds for scale or video with the 530kv motor. Drops it down to about 1250 rpm.

Really not much of a drawback at all with 12s except maybe the spark and having to buy 2 packs instead of 1.

[flyinghigh450]

Originally Posted by veloflier

I have heard most people flying 12s, but seen the random 6s. This is my first larger heli. I have a 450, and a 500. Figured it was time for something bigger. That and I am leaning more towards scale flight. Figured 12S would have more power.

6S will be more than enough and ive even seen 5S 600 size scale helis with bigger mAh packs for longer flight time..With a scale heli,you won't pull twice the amps or even close to twice the amps with a 6S setup vs a 12S setup for the simply fact that your scale flying and not pushing anything hard..You'll pull around 40amps if that..

You can go either way but 6S will be fine..

[minititinflyer]

if you had the motor i got the castle 1717y1 1500kv it would be beast on 6s alone

[Andy01]

You certainly do not need 12s to get more power. A 600 scale heli should fly scale circuits on less than 1000W, which a decent 500 heli can produce easily, so power is not the reason.

As said above, efficiency and low amps (low heat), with low loads on lipos (cheap low C rated lipos can be used). Also many larger scale Helios tend to be tail heavy so you need extra weight up front, and the weight may as well be lipos, not ballast. You could, of course, run a large 6s (two in parallel, instead of series), but why ?

Colin

[seanh]

6s and 12s power is very close. The only real difference is the efficiency between a LV and HV setup.

on my left and right I have helis that can produce 3-5KW, which one is 12s? Who cares, so long as you design your system for your requirements.

the 12s mindset came from a time when high current systems weren't around or were very expensive. That was back in the time when we were limited to something like 35-40c batteries. This isn't the case anymore. If you want 300amp 6s setup, you can do it.


For ease of use, go with 6s on your scale setup.

look around in the scale form and see what power systems they suggest.

[Andy01]

As I said above, 12s would be better for scale (I have two 12s scale helis) but not because of power, since power is not a factor with scale.

Heat can be be a big issue with scale (unless you live in Alaska perhaps), and a 6s setup will almost always run hotter than 12s because the amps are twice as high.

Also, as said above, many scale helis need more nose weight, so it is pointless running 6s with ballast, or even running a large parallel 6s system.

Colin

[ahahn]

Originally Posted by Andy01

As I said above, 12s would be better for scale (I have two 12s scale helis) but not because of power, since power is not a factor with scale.

Heat can be be a big issue with scale (unless you live in Alaska perhaps), and a 6s setup will almost always run hotter than 12s because the amps are twice as high.

Also, as said above, many scale helis need more nose weight, so it is pointless running 6s with ballast, or even running a large parallel 6s system.

Colin

Well the amps may be twice as high, but the battery capacities are twice as big, and there are half the number in series. What that means, if you calculate it out, is that the 6s pack resistance is 1/4 the 12s pack resistance. So heating is a wash. (think about a 12s1p3400 pack vs an identical 6s2p7800 pack, each made with 12 3400mAHr cells. If you do the math, each cell provides the same current, showing that pack heating is the same. You need the same C rating for both the 6s and 12s setups. But current output is not only C, but also the cell capacity.

Also the ESC will be a higher amperage, but LV ESC. That means more FET's, but also FETs that have less resistance than the ones used in a HV setup. Again another wash.

Finally, the motor Kv will be twice as large for a 6s as a 12s. If you do the math, that means the internal resistance of the 6s motor will also be 1/4 the resistance of the 12s (half the winds, and double the cross-sectional area). So again the heating is the same.

[Andy01]

Not going to argue with your maths.

My understanding is that a 12s pack developing 1000W will require 1000W / 44.4V = 22.5A flowing through it.

Take an average 3400mAh 25C (3.4 x 25 = 85A capable) lipo and draw 22.5A from it, and it will run quite cool. If you draw 45A out of the same pack, it is likely to run a fair bit hotter.

In my 12s scale helis, the lipos are always the coolest part of the system - the motor and ESC always run hotter, especially the ESC if the fuselage is completely closed in.

One would have to ask why so many people are changing from 6s to 12s if 6s is more efficient (less resistance). Nearly everyone I know who has made the change has seen systems run cooler, longer flights (ie. improved efficiency) and/or more power (obviously power is not an issue in a scale heli). Seems to contradict the maths a bit

Colin

[ke6d]

Originally Posted by ahahn

Finally, the motor Kv will be twice as large for a 6s as a 12s. If you do the math, that means the internal resistance of the 6s motor will also be 1/4 the resistance of the 12s (half the winds, and double the cross-sectional area). So again the heating is the same.

Something is not right with your logic on the motor specs. Please check out the specs for this motor. The two variants are basically built on the same core/material with different wiring configuration. Please note that the lower KV motor has significant more power while drawing much less current.

http://www.scorpionsystem.com/catalo...5/HK-4025-550/

http://www.scorpionsystem.com/catalo...K_4025_1100_5/

When I was running 6S on my T-Rex 600, I would be lucky if my 6S pack lasts 75 flights. Since converting to 12S a couple years ago, my pack counts are now over 150 cycles and are still running.

[ahahn]

Originally Posted by ke6d

Something is not right with your logic on the motor specs. Please check out the specs for this motor. The two variants are basically built on the same core/material with different wiring configuration. Please note that the lower KV motor has significant more power while drawing much less current.

http://www.scorpionsystem.com/catalo...5/HK-4025-550/

http://www.scorpionsystem.com/catalo...K_4025_1100_5/

When I was running 6S on my T-Rex 600, I would be lucky if my 6S pack lasts 75 flights. Since converting to 12S a couple years ago, my pack counts are now over 150 cycles and are still running.

So if you look at the those motor specs, the 550 has a coil resistance of 35mOhms, while the 1100Kv has a coil resistance of 8mOhms, just about the factor of four (actually a bit better!) I was claiming from general principles. If the 550 pulls half the current of the 1100, then the power going into heating the motor coils will be just the same (heating is just the square of the current times the resistance.

Now to the battery. What people don't consider is that to be equal, the two setups need to carry the same total battery energy.

The easiest way to see this is to take your two 6s packs that you now run in series as a 12s, but instead hook them up in parallel for the 6s setup.

For the sake of argument, lets say you are pulling 50A for the 12 s setup. Note that you still need twice the current (100A) for the 6s setup to make the same power as the 12s. However each 6s pack is supplying half of that current. Or in other words, each of the 6s packs is supplying the 50A for 100A total. Since in both 12s and 6s, each pack is supplying 50A, the battery heating is the same. No difference.

It is all just simple math, No hype.

[ke6d]

Originally Posted by ahahn

So if you look at the those motor specs, the 550 has a coil resistance of 35mOhms, while the 1100Kv has a coil resistance of 8mOhms, just about the factor of four (actually a bit better!) I was claiming from general principles. If the 550 pulls half the current of the 1100, then the power going into heating the motor coils will be just the same (heating is just the square of the current times the resistance.

It is all just simple math, No hype.

If there is no difference, how come the 550KV motor produces 27% more power than the 1100KV? (47% more peak power) What happened to the energy that the 1100KV motor was supposed to produce?

I am pretty sure that you are pretty much alone when preaching that there is no difference between HV or LV power systems. There are posts that you made before on this subject but you seem to be the only who are saying that.

If there is no advantage to HV, how come the utility power transmission lines are 100+ KV instead of 110V? I think you do know the answer but just did not want to publicly admit it.

The specs for the 2 motors mentioned above would convince anyone who wants more power to their setup would go HV in a heartbeat - Simply drop in a motor of the same size and weight and you would get 27% improvement in continuous power and almost 50% improvement in peak power -- Remember that there is no black magic involved in designing these motors, the LOW VOLTAGE MOTOR (high KV) SIMPLY WASTES A LOT OF ENERGY vs THE HIGH VOLTAGE (low KV) MOTOR hence it is producing much LESS POWER.

[Luvmyhelis]

I see these same arguments all the time still going on in the 450 world with the 3s vs 6s thing.

Pretty much the identical low vs high voltage arguments. There are hundreds of pages of documentation to support the high voltage systems, but guys still argue.

In my 450s I run highly modded 6s systems. For instance. taking the exact same rated 3s motor and running two 1100 3s packs, vs the same performing motor with 6s and the exact same batteries in 6s config. The first setup (3s) produces an 11:13min flight time with the Ice50 (highly modded with arctic ice'd sinks and larger aftermarket caps) and the system comes down smoking hot. You could fry an egg on the esc and motor and the batteries are very warm (almost hot) to the touch.

The 6s system turnes in a fully documented 18:30min flight with the exact same batteries doing exactly the same flight patterns. The motor and esc came down barely warm to the touch. The batterys were cool. In fact both systems have exactly the same energy reserves with identical loads being flown on the same frame!

This was publically posted in the 450 forum on a stretched 450 running 420mm blades with an HH raised tail system.

Pretty much a similar low vs high voltage argument all over again.

I also owned an 6s Esp and have a 12s Esp. And my current 12s Esp is far more efficient. Due to this raised efficiency it also runs a much larger can now and produces similar flight times to its 6s version but has much higher performance. To put it mildly, I will never go back to a 6s system again. And yeah, I have batteries now with well over 250 flights on them running the HV setup that still perform well. Most who have done this same thing have more useable power and much longer flight times using the exact same packs. Just wired in differently. The power reserves are identical. But far more efficient. So in my case I was running dual 4000ma packs in parallel on 6s, and now wired in series for 12s. Same power reserves! So my new 12s system has more useable power with the same batteries and still has better flight times to boot. Plus the electronics stay much cooler.

The point is active amperage draw. And 6s draws twice the current to produce the same effect. This amperage draw also results in higher heat production. This higher heat production is measured in lost power throughout the system. Aka, less efficiency. Alot less!

So if you have two identical setups. One 6s that is rated exactly the same as the 12s version. The 12s version will consistantly outperform the 6s version. Not only will it have more useable power throughout the entire flight, but have longer flights with the same battery reserves. Also the 6s version will always run warmer than the same rated 12s version.

My own personal results with 6s vs 12s in a 600 are similar to the same results I posted with 3s vs 6s. Along with countless others. There really is a reason for the move over to 12s. Not just idle bragging, but actual facts.

[Andy01]

Originally Posted by ahahn

For the sake of argument, lets say you are pulling 50A for the 12 s setup. Note that you still need twice the current (100A) for the 6s setup to make the same power as the 12s. However each 6s pack is supplying half of that current. Or in other words, each of the 6s packs is supplying the 50A for 100A total. Since in both 12s and 6s, each pack is supplying 50A, the battery heating is the same. No difference.

It is all just simple math, No hype.

This, of course, (if I am understanding you correctly) assumes that people running 6s are running two parallel 6s lipos.

In fact, most 6s setups have a single lipo, which bears the full 100A, so it will clearly get hotter I suspect.

Colin

[Martin353]

My head hurts

I was looking at this with interest as I've just stretched my 550 to 600 and put it in a scale fuse. I'm still running stock motor, gear and pinion but have changed esc to a scorp that will do anything from 6s up.
I'm still using 6s at the moment but was looking at 12s (hence the esc )
After reading this I'm more confused than ever lol


---
I am here: http://tapatalk.com/map.php?fpmtv2
I'd rather be flying than typing

[ahahn]

Originally Posted by Andy01

This, of course, (if I am understanding you correctly) assumes that people running 6s are running two parallel 6s lipos.

In fact, most 6s setups have a single lipo, which bears the full 100A, so it will clearly get hotter I suspect.

Colin

You got that exactly correct!

What I am saying is that there is nothing INTRINSIC about 6s being less or more power than a 12s setup.

However if you put effectively bigger and heavier packs (total weight) on a 12s, then yes I would expect it to perform better. Likewise if you put on a bigger motor, or one that has a Kv that is more than 1/2 the 6s system, then again, the 12s will perform snappier.

However you can do the same thing with the 6s system---with the proviso that you can find a motor with, lets say, 10-20% higher Kv than your original motor. This isn't trivial by the way.

So why do people claim their 12s systems perform better than the old setup on 6s?

Well because I am guessing they actually do!

Why, well because the total battery is bigger, the motor is greater than 1/2 the Kv (lets say 600 rpm/V rather than the 550 rpm/V in the current example), and probably most importantly, they are comparing the upgraded version, using nice fresh new lipo packs, of a higher C, than the old worn out and abused 6s lipos of the original system.

So I am not saying that you can't get better performance in 12s upgrades, only that you can accomplish the same thing with a 6s system too.

And I use numbers to show it, not "feelings".

[kenobi36]

I understand that in motors like 4035 and bigger, current would go over 200A and will need very thick wires and connectors.
In smaller systems I don't see any advantages.

It's strange that Scorpion specs of 4025 1100kv is worse than 550kv.
It has 4x lower resistance so heat at 2x higher current should be same, rotating speed should be the same so cooling fan also works same.

How to change 12s motor to 6s motor:
Wee take out 2 turns of coil out of the 12s motor where there is normaly flowing 1A current.
Cut it in 2 pieces, connect palarel and put back inside the motor and push 2A current.
After this change when wee will look at one from two wires then the curent will be only 1A going through it. Nothing changes. Resistence and current on each wire is the same in 12s and 6s setup.

Nothing totaly changed. 550kv motor runnig at 12s should have same power specs as 1100kv motor at 6s.


I found 3s and 6s KDE motor for 450class specs:

KDE DIRECT 450XF 1750
Kv 1,750 RPM/V
Continuous Current 33+ A
Continuous Power 725+ W
Maximum Efficiency 90%
Rm (Wind Resistance) 0.026 Ω

KDE DIRECT 450XF 3500
Kv 3,500 RPM/V
Continuous Current 66+ A
Continuous Power 725+ W
Maximum Efficiency 90%
Rm (Wind Resistance) 0.009 Ω

[willr001]

As an electrical engineer, the motor analysis showing them identical is pretty correct, but as others have said, it's all in losses elsewhere. If you were to measure the voltage across the motor, you'll probably see 1-2 volts less than at the batteries, with a lower voltage setup losing closer to 2 and a higher voltage closer to 1. Now think, 1 volt out of 50 volts is a 2% loss, but 2 volts out of 25 volts is an 8% loss. Your voltage drop in wires will be twice as high, and your esc headroom voltage will be the same. Higher voltage system equals more usable power.

Tradeoff can be bec efficiency, and sparking damaging connectors, but there are plenty of ways to mitigate those things.