Matthew007

Yip..$100 including ship.

The motors specs and can looks exactly like a FEIGAO 540S (Sensorless) (same color, weight, power,amps..etc), except with a 3.17mm = 1/8" shaft and a heatsink in the middle.

The 120A rated ESC was used in the Heng Leng Mad monster with a 3S lipo 11.1V 2100mah battery.
[link=http://www.youtube.com/watch?v=1sUq9f2WGio]The video[/link]

It's pretty big at 70x50mm but that's good for cooling and maybe mounting a $3 cpu fan that TH charges a million dollars for.

The icing of the cake that got me to decide to order was the "program card."
It has a ton of automatic and constant features like temp cut-off, voltage, current control, etc. The manual is here:

http://www.modellfun.com/ebay/MFC_manual_en.pdf

Hopefully it's not the icing of a cake made out of sh **. (Disturbed's David Draiman comment on pop-music heheheh).

Oh yea the link I ordered from:
[link=http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=330200319353]Order place to buy the thing link[/link]

The draw backs:
75% motor efficiency (still better than brushed mod motor)
No name-brand = no reliability records and being flamed by major geektrolls.
Replacement part availability
And whatever you guys can add that makes sense.

P.S
This is not an advertisement
Let me be your crash test dummy.
I have a 4 year old Traxxas Bandit rolling chasis that flexes and vibrates I can detroy to test it out until I get my Tamiya F-150 (Ta-01/02) Which will be done probably by 2nd week of January,
Yea the guy who asked those stupid questions from the seller was me.

Also, will a sensorless motor of the same KV rating provide more torque general? I see the traxxas 3500kv sensorless motor is rated as a 10T..or is it literally 10t wound? Confusing. It would be so nice if hobby stores/manufacturers uploaded a torque/current/power/rpm/efficiency curve like Mabuchi does.
But I guess less informed consumers are better for business.

Takedown

My Feedback: (23)

That ESC is huge! I woulda saved a little more and bought castle's new sidewinder 5700.

pede_187

I think I have that motor. Except it's blue. It's rated for the same voltage and is the same KV.

tashspop

My Feedback: (1)

i'll be waiting for your thoughts on this. is this your first brushless setup?

Slo-V Flyer

The Traxxas VXL motor is actually 10 turns, not equivalent to it (or it'd be one slooowww 10 turn they compare it to).

3300 kv is kinda on the slow side as you might have guessed, so you will need to gear up crazy even with 11v lipo to get "fast" speeds. I run a 2700 kv Feigao 9L (3mm shaft) in my Rusty and on 3s lipo I gear it 23/84 or 25/84 and reach about ~35+ mph, but it's fast enough for me and it pops rolling wheelies all day long.

What do you mean by Also, will a sensorless motor of the same KV rating provide more torque general? Can you clarify what you are asking? That system you bought is already sensorless if that's what you mean, and if 2 motors are the same kv rating, the one with more max amp draw will have more torque.

Here's the formula for torque in a bl motor:

1355 / kv x amp = in/oz. of torque.

For example:
Castle 5700 kv motor @ 100 amps: 1355 / 5700 * 100 = 23.77 in/oz torque
Feigao 9L 2730 kv @ 64 amps: 1355 / 2730 * 64 = 31.75 in/oz torque
Feigao 7XL 2382 kv @ ~94 amps: 1355 / 2382 8 94 = 53.47 in/oz torque

Those are all based on the manufacturers claim that the motors rev up to X rpm per volt (unloaded hopefully?).

Does that help?

Matthew007

sidewinders are all back order and I dont think the esc is as good or programmable as this one.

Pede, yes I think it is the same as the redcat BL motor system. But for $10 less I got a better ESC and a Program thingy.

Tash, yes. I will try to post pics and better yet a vid someday if I can hook my fuji finepix to my controller lol.

Slo-V, I know that stall torque is the max torque which occurs at max current draw so I understand the relation.

I was asking that compared to sensored, do sensorless motors of the same kv rating generally perform better.

Yes the 3300kv motor will be slower compared to the higher ones, but I saw a video of the redcat setup on [link=http://www.youtube.com/watch?v=8WZIz9wI9lY]youtube [/link] but on a lighter monster truck I believe with 6 cells that seems to go pretty fast.

I can't get any info on Novak's "economy" EX sport motor's amp draw but the 3300kv version is 4-7 cells with a power output of 165w (Assuming at 7 cells).
The ebay motor is 420W at 18V. If P=IV and if the current stays the same, 420/18 * 8.4= 196W. I know this is a rough estimation.

I don't really care about speed, I'm happy with 25-30mph if I can control it and drift when I want.
I really wanted longer run times and much less motor maintenance.

Takedown

My Feedback: (23)

The sidewinder is computer programable though. Should have plenty of adjustable features just like the Mamba Max.

CustomTamiyas4Life

My Feedback: (34)

Holy ESC!

ashunte

so you get it yet? i was thinking about grabbing one too!

Matthew007

Ha! It's from China dude lol EDIT: If you meant if I ordered it, then yes. If you meant if I got it home yet, then no.
The distributors and modellfun.com are German though.

My Tamiya F-150 is still on backorder even though tower said late december.
The 2.2" wheels and tires plus the extra ball diff i ordered from tower arrives Jan 7th.
My Bearings will come on Jan 10th from china of course.
I just ordered an aluminum motor mount and a pinion set of 21T and 24T.

Thinking off getting an aluminum center main shaft and titanium universal swing shafts (CVD in ure lingo?) from [link=http://www.asiatees.com/]here[/link]

Tower shipped them UPS so they might all come 1 month late and damaged.

So I wont complete it by mid January But I'll have a decent setup...hopefully.
With my luck tower will ship me a kit with two left rear suspension arms like when I received my Traxxas Bandit 4-5 years ago lol.

tashspop

My Feedback: (1)

i never knew that torque formula. going off the manufacture specs, my big setup on my maxx is producing 133.905 in/oz [sm=punching.gif]
i really think there's something missing here, or at least i'm missing something.
a motor will pull less amps at higher voltages. now given that it produces the same wattage, using this formula indicates that increasing voltage reduces the motors torque?

Slo-V Flyer

No No No, if you keep the gearing the same, the more volts, the more amps you draw.

What kv rating is your "big" motor and what is the max amps it is rated to handle?

With more voltage in a system, it means you need less amps to make the same power, not that the motor will draw less amps. SO that means you can use a smaller pinion to keep the amps low and let the volts (= rpm) do the work. Or keep the same exact gearing, and the motor will draw proportionally more amps, and give you more power and of course more heat and less runtime.

power (watts) = volts x amps... so going from 7v to 11v you need less amps to get the same power (watts).

Amps = Volts / resistance (ohms).

If you keep the same load on the motor, and assuming the internal resistance of the motor stays about the same (resistance becomes higher though with more heat among other things), as you can see, the more voltage you plug in, the more the amp draw will be. Don't use that formula to figure out a motor's max amps, it doesn't quite work that way.

studysession

What is that installed in?

tashspop

My Feedback: (1)

oh, see i knew i was missing something. i don't have a amp rating for my motor. i do have from manufacture 3528 watts and can take upto 36 volts. what i did for the formula was take the 3528/21 volts(i'm running) which gave me 168 amps. the motor is 1700kv. i then put that in the formula you provided to get 133 in/oz of torque. thats with a fresh charge. my nominal voltage is 19.8 which at 3528watts or 178 amps. that gives me 141.78 in/oz torque.

where i was lost, looking at the same motor 3528watts ran at 36volts would require 98 amps. that gives 78.11. i don't know exactly how much my system is putting out because i have gotten an eagletree data loger yet. but i run through 4600mah of a123 cells pretty quick.

i know this is all on paper and everything is different in real world. i guess i'm confused with the part where you said (if you keep the gearing the same, the more volts, the more amps you draw.) i always thought i motor can produce x power. ie watts. so if it takes 100amps at 10 volts to produce x, then it should only take 50amps at 20 volts to produce x. what i'm saying is electric motors are only able to produce a certain amount of power right? or does this number just go up until it tears itself apart?

snellemin

Don't forget that the kV drop is greater as the amp usage goes up. Might not be important for everyday bashers. But for a 2 second dragrace, it makes a difference.

motor kV*motor resistance*amperage

Matthew007

studysession,
that's installed in their Heng Long "Mad Truck." The electrics is by modellfun.com

[link=http://modellfun.com/b2b/products/blmonster.php]http://modellfun.com/b2b/products/blmonster.php[/link]

Here is a simulation data curve for a mabuchi 540sh motor:

[link=http://www.mabuchi-motor.co.jp/cgi-bin/catalog/e_catalog.cgi?CAT_ID=rs_540rhsh]sim[/link]

*Click on the blue links to the right of the motor designations.

Under no load, when voltage doubles, the current draw doesn't go up that much at all.
What makes current go up is frictional or torque force required to move an object with weight from rest. Friction is like a constant torque force always fighting your direction of mobility.

You can obtain the frictional losses of your R/C buy measuring your amp draw with your motor on nothing and then measuring it with your motor installed and the wheels off the ground. The current draw will go up and then settle, but will be higher of course than with the motor running free.
Since the voltage is constant (by your control) and the motor is the same, you can use this technique.

I did a test with a brushed motor coupled to a mod motor. It didnt matter at what voltage; when I took off the brushes on the mod motor, the current into the motor being powered dropped around %27-30.

studysession

Thanks -
The guy with the EBay auctions - I am tempted to get their RC18T clone with brushless setup. For the price hard to go wrong. Maybe after I move will get one then.

Slo-V Flyer

Well, you know how much power you want, but what you don't know is what to gear it so that when you UP the voltage, the final result, Power (watts), stays the same, and want the amps therefore to go DOWN. I.e. 10v * 100 amps = 1000 watts. You get a 20 volt battery, so now you know that you want to KEEP the motor at 1000 watts, but with 20 volts you want 50 amps, like in your example.... So in order to keep the amp draw low (hopefully even less than before so it's ~50 amps) you will need to use a much smaller pinion... here is why:

What ordinarily will happen is this.. with the same amount of load on the motor (i.e. same exact gearing, tires, weight etc etc), the amp draw will go up proportional to the voltage increase... up to a point until the motor's wire coils reach a saturation point with the amps, beyond which it will just generate heat and become inefficient.... So what you want is to use the smaller pinion, so that with the increase in volts, you will increase the total RPM, but because of the smaller pinion the motor can turn over more easily, so it won't draw as many amps... which means with trial and error, you will find your 50 amps or so and voila, you will still be at 1000 watts peak, but now with half the amp draw, and possibly twice the runtime (assuming the 10 volt and 20 volt batteries are the same capacity).... get it?

As for that 36 volt motor you have, yes, without the factory's maximum amp rating, we can only theorize that it will draw about ~98 amps on 36 volts to reach it's max 3500 watts. But again, as you said without a data logger we won't know what it's doing (amp draw, etc) so that we can try to use our available practical voltage (battery voltage) and gearing to keep it's amp draw in check and still get good power, and all that.

Basically, the motor will continue to want to suck in more amps the more voltage you feed it. The max power rating is only there to let you know what you can expect it to perform, but you will need to gear it correctly with your particular setup to reach your performance vs. runtime goal or whatever it may be.

Hmm that help you a little?

Matthew007

This is so wrong. Power=Torque x RPM and P=V x I Up the voltage : more power regardless of gearing. Gearing changes the ratio of torque and rpm, either up/down or down/up respectively.

To understand better, maybe knowing how a Prony Brake works will help.

Infact you can easily make the bottom version:
[link=http://my.voyager.net/~jrrandall/PronyBrake/PronyBrake.html]prony brake[/link]

or this version:

[link=http://www.geocities.com/koneheadx/measuringshaftpower.html]prony brake II[/link]

If you build either of said brakes, this discussion becomes mute and proven/disproved through reality.

This is Matthew007 and I approve this message.

HAPPY NEW YEAR!

Slo-V Flyer

I don't think you understood what I was saying. All Pony brakes and horse play aside, what I was trying to get across in simplified terms was that going up in voltage with the gearing being the same would cause the motor to pull more amps which = more total power available i.e. volts x amps = watts...

for example...

7v x 10 amps = 70 watts,

Running higher volts through the same exact truck and motor and gearing might roughly yield...

14v x 20 amps = 240 watts, or about 4 times the watts.... remember Ohms' rule, amps can go up or down proportionally to voltage ASSUMING the resistance is the same..

(Amps = Volts / Resistance....
10A = 7v / 0.7 Ohms
20A = 14v / .7 Ohms.. just to help you understand what I am trying to say....using a hypothetical situation where the motor is NOT reaching its max amp saturation and has "wiggle room" to draw more amps)

SOOOOoo, if I gear down my motor with a smaller pinion, lets say I go down from 20t to 10t pinion, and run DOUBLE the voltage, say go from 7 up to 14 volts , I have effectively halved the load on the motor with the smaller pinion, and because I have cut down the load by 1/2 on the motor, the amp draw would be prevented from being doubled, to say staying roughly similar as the amp draw was on 7 volts with the bigger 20t pinion.... get what I mean?

So.. let's take a rough example of what I mean by using more volts, smaller pinion or low gearing and we might get something like...

14v x 5 amps = 70 watts... same as when using 7 volts and 20t pinion, but now we lower the amp draw somewhat and get more runtime and cooler running motor... This is all a little bit hypothetical but should get my point across..

What I am trying to say is, and I don't know why I started to go into this tangent in the first place before, in order to keep the same performance with higher voltage, you need to use a smaller pinion to ease the load on the motor which will therefore reduce the amp draw which will allow the potential total power to remain the same as before, except now with reduced amp draw you get the benefit of extra runtime....

There, that should be more clearer to understand. I hope....I don't know how I even started this whole "debate..."

Slo-V Flyer

And no you are wrong, more volts does not automatically mean "more power regardless of gearing." I can up the volts from 7 to 14 volts, and then switch from a 25 pinion to a 12t pinion thereby reducing the load on the motor quite a bit, and so the motor will likely pull less amps and therefore the volts x amp formula would result in not that significant of a power increase, if at all.... see what I mean?

d16z6

With more voltage you have more potential to overcome the existing higher resistances that wouldn't otherwise be traversed by the lower voltage settings, thus allowing the potential for more current flow (amperage) when the situation demands it.

You need voltage to overcome resistance to start flowing current. The more voltage you have the more current you can possibly flow if called upon.

Matthew007

ok in a brushless, ignore firctional losses, 7-14v = 2x RPM original 24T to 12T=1x RPM and by RPM I mean at THE WHEELS.
In theory, at full throttle the motor will run 1x speed at 1 volt and 2x speed at 2 volts at the motor shaft, gearing dont matter.

Another thing we need to consider is Drag I was not including drag, and I mean drag caused by weight.
Example, you ever hear of lighter crank shaft pulleys? They DO NOT increase horsepower, they decrease the time it takes to go up into the rpm curve through decreasing drag. When you increase your pinion size, you increase drag when you accelerate. Once you reach top speed, it dont matter.

So.. ignore drag and friction. double the voltage of the motor and half the gear ratio you will get the same RPMs but you will get more power because you will have more torque.

And like you said, P=I^2R or V^2R (2V)^2=4V so you'll have 4 times power to agree with the law.

My point is this, just try to imagine the motor fighting the drag during acceleration, we both agree this causes higher current draw.
Yes, if you decrease the pinion size in this situation the current draw will be less because it will reach top speed quicker.

When I said no matter the gearing, i meant at constant rpm or desired speed (cruise), the gearing doesn't affect the current draw.
Also, frictional losses remain relatively constant in the bearings, gears, etc.

Slo-V Flyer

Ok I can see we are sorta' talking about two different things, and that this argument has been done before like a dozen times. I agree by using a smaller pinion with 2x voltage you will increase the *available* torque, even though you might keep the wheel speed constant, and therefore still have more power potential.... But I was really not talking about drag caused by the larger pinion and all that. All I was trying to point out was... well I don't even remember now. I think what I was trying to say was to get better runtimes and keep the TRUCK speed the same you can gear down if switching to higher voltage. Yes if you put a higher load on the motor setup that way, the amp draw will go up there somewhere again, and that's how you will get more power potential with higher voltage than before, but keeping everything else the same i.e. weight of the truck and all other factors, yes you will get better acceleration simply due to the fact you use a smaller pinion = more torque, and yes of course the motor RPM will be faster with higher volts even though the wheel RPM will be the same with a smaller pinion if that's what we're going for. But because the average amp draw will be less with this setup because of the motor not need to turn a larger pinion (because the leverage of the smaller pinion is "easier to turn" ) chances are you won't be using up the extra power that much other than gunning the throttle a lot, so you will get better runtimes....

tashspop

My Feedback: (1)

alright, i didn't mean to get anybody thinking hard here. sorry about that. everything said makes since to me and i do feel like i understand this better now. thank you both for educating us on this.

back on topic, did you get this setup yet? installed?