Motor current draw findings...

[neurokinetik]

So I just put together a little rig that connects up my stock battery holders directly to the motor with the ammeter in series. On a fully charged set of NiMH batteries, here's what I found:

(These are unloaded numbers, BTW)

Stock motors
Stage 1 motors: 0.26A - 0.35A
Stage 2 motors: 0.45A - 0.53A

Spin Brush motor: 0.28A

Tamiya Plasma Dash: 1.7 - 1.8A

Team Orion Elite stock motor for Micro RS4 (180 type motor): 0.21A

GPM MH038 Hi Speed 35T modified motor (180 type): 0.27A

(Need to borrow a stock X-Speed to test)

Experimental and modified motors
Spin brush armature and can, stage 1 magnets, endbell, and brushes: 0.37A

Stage 1 with spin brush magnets, timing advance, and BB endbell: 0.18A

MiniZ Racer Z130-A-BB armature with timing advance in stage 1 can with spin brush magnets: 0.40A

Stage 2 with spin brush magnets and timing advance: 0.60A

Stage 2 reduced to 44 turns, timing advance, and Drac's Neo magnets in Auldey BB can: 0.70A

25 turn (28 Ga wire) armature in stage 2 can: 0.89A, but it pulled as high as 1.4A before it topped out.

Custom 35 turn (28 Ga wire) in Stage 2 can with timing advanced: 0.90A

Custom 35 turn (30 Ga wire) in Stage 1 can with timing advanced, and spin brush magnets: 0.70A

Custom 35 turn (28 Ga wire) ex-Plasma Dash armature in BB motor can, timing advance, thin Neo magnets: 0.58A

Custom 30 turn (26 Ga wire) 180 motor: 0.50A

Custom 2 x 21 turn (30 Ga), timing advance, spin brush magnets, ball bearing can: 1.7A

[sherifx]

awesome! great great thread. so from this I gather that my setup is drawing in the area of about 600mA. Now the question then is what is the limit of the ESC then?


sherif

edit: I guess the next step is to figure out how to extract the highest amount of torque and speed out of the motor w/o exceeding the above mentioned limit.

edit 2: To give some people an idea of what the results are of some of the motors mentioned above. I'm running a the Stage 2 arm w/ spinbrush can & magnets, and I've got it in my AWD skyline with hard tires & the thing keeps all 4 tires spinning with the Yellow (4.40) final drive gearing.

[neurokinetik]

Originally posted by sherifx
Now the question then is what is the limit of the ESC then?


Still unknown. The stock 3004 FETs that the Mini-Z used were only good to 3.5A. The IRF7389 is good up to 7.3A. The Si4562 is good to 7.1A.

Toshiba had a press release from around May of this year showing some new packaging of these types of chips that were capable of around 13A. :)

The part numbers are totally different than what is in the XMod. (The chip just says A1792)

[Rez]

Sticky.

[geofroley]

Can you clock RPM's with that little machine of yours neuro?

[sherifx]

Hrm... Neuro, I'm curious as to how you setup your testing equipment b/c I was just thinking of going with a Yeah Racing BB Can w/ balance armature, neo magnets & carbon brushes, wrapping the arm with about 42 winds of 30-gauge... The question is once it's done, I have no idea what the current draw will be... I'm guessing somewhere in the range of 0.70amps or so... though, I'd like to play with gauges (I also have 22 & 26) so that I can extract more torque along with high RPMs for my drift spec skyline.


sherif

[sherifx]

Well, I'm completely editing this post. Basically, last night in a fit of boredom I wound a 42-turn motor with 30gauge wire, and threw it in a spinbrush can. It seemed really promising, with tons of torque decent revs,... but once it was under load, it sucked... horribly heh. My SBPStage 2 is infinitely better than it, and even after 5min of just tooling around, the thing was hot... which makes me wonder, if its a problem with my winding, or just what I'm trying to do in general. Anyways, I originally started this post asking Neuro if he could test the current draw from this type of setup, but I'd like to trouble shoot my winding first... I've included a really crappy pic from my camera phone, but in it, I show the direction of how I wound the motor. I had to reverse the polls on the connection b/c how I wound it, reversed its direction... ah trial and error :rolleyes: lemme know if you see anything wrong:

http://www.freebmw.net/sherif/arm.jpg

sherif

[neurokinetik]

It looks like a better winding tutorial is in order... ;)

Anyway, it's hard for me to decipher from the pic how you wound the motor.

Here's how I've done it:

http://users.adelphia.net/~neurokinetik/winding.jpg

Start at the cyan arrow. Solder the connection to the terminal, then follow the yellow arrows around the pole. Repeat until you have the number of winds you want. (Don't lose count :p ) Finish that pole by soldering the wire to the next terminal, as shown by the red arrow. Then move on to the next pole.

Oh yeah, almost forgot to mention:

Tamiya Plasma Dash: 1.7 - 1.8A

[Skurge420]

bret....i have a stock SBP motor if ya want ot borrow it........PM on ubrf or something......or reply here

[SuperDragon]

What is the the max current draw that the stock fets can handle? Or what is the max current draw of a motor that has been installed in a xmod with out burning it up.

SD

[neurokinetik]

Originally posted by SuperDragon
What is the the max current draw that the stock fets can handle? Or what is the max current draw of a motor that has been installed in a xmod with out burning it up.

SD

Again, we still don't know the limits on the stock FETs. I have run a motor that draws 700mA for a full set of IC3 batteries with no ill effects. That is with it geared as tall as possible, too, (blue gear set) which increases current draw even more.

[SuperDragon]

neuro - I'm tring to figure out if a 15 turn dual wind motor will kill the stock fets. Any thoughts on it?

[neurokinetik]

A 15 turn double is effectively a 7.5 turn motor current-wise. Yeah, I'd expect to smell some smoke. :lol:

[SuperDragon]

=) hmmmm. Smoke. Letting out the magical smoke that makes things work is bad. I wound up a 25 double with like some 30 gauge wire. I wounder if the smoke will fly on that... I know i need to upgrade the fets. I've fallowed what you did and it's pritty kickin. ever thought about using a mini-z external turbo?

SD

[neurokinetik]

Originally posted by SuperDragon
ever thought about using a mini-z external turbo?

SD

No, not when I was able to come up with one on my own that works better and costs less...

[neurokinetik]

Originally posted by Skurge420
bret....i have a stock SBP motor if ya want ot borrow it........PM on ubrf or something......or reply here

Actually, I have all the parts for one already, I just need to put them all back into the same motor. :lol: I figure the current draw will be less than the stage 2, but a little more than the stage 1, just by the number of winds and gauge of wire used.

[SuperDragon]

on the kind of turbo that you made with those mosfets or fets could you use the Pos and Neg leds comming off of the board to trigger your turbo and have a pos and neg to the bat as well with a set going to the motor? Do you think that would still work?

SD

[neurokinetik]

It might still work, but you'd lose the benefit of having the better power dissipation at all but wide open throttle, I would think. I'll have to look into it.



Back on the subject of current draw...

I wound a 35 turn armature tonight, with 28Ga wire. It pulls .9A. Sounds pretty beefy, A bit faster than a stock stage 2, but with alot more torque.

I think I'll wind one with 35 turns of 30 Ga wire and see what the difference is. In theory, it should gain top speed, lower current draw, and lower torque. I wonder what gauge of wire PN racing is using on the S03 and their other motors...

[sherifx]

neuro, what do you think would be the max windings of say 26 gauge? 25, 30 turns maybe? I'd like to know the current draw of such a setup as well. I'm guessing anything under 1 amp current draw should be alright... though don't quote me ;)


sherif

[neurokinetik]

35 turns of 28 was pretty tight. If you can get 30 turns on it, I'd be surprised, or else you are just better at it than me. :o

It'll never be under an amp with that few turns and thick wire, though. Remember that the Plasma Dash is 27 turns of 26 Ga, and it draws 1.7A...

[neurokinetik]

Well, I now have three different 35 turn motors wound.

The first is using the old Plasma Dash armature. I used 35 turns of 28Ga. It sounds like crap, I think the brushes need some work on it.

The second is also 35 turns of 28Ga, using an old stage 2 armature, in a stage 2 can, with stage 2 brushes. I advanced the timing on the commutator whiel the armature was empty and wound it that way. It draws 0.90A, and when it spins up, you can tell why. Pretty fast. In the car, acceleration from a stop is nothing special, but after about the first five feet, it seems promising.

The third is 35 turns of 30Ga, using an old stage 1 armature with timing advance (actually identical to the stage 2 armature) in a stage 1 can with spin brush magnets. The spin brush magnets make up somewhat for the loss of torque of the smaller wire gauge, but this one does have a bit higher top speed than the 28Ga version. The current draw is much lower with the thinner wire, at only 0.70A. On the bench, it sounds quite healthy, but not quite as beefy as the 28Ga version. In the car, it runs almost the same as the 28Ga version. I really need that speed checker to see if there is any appreciable difference.

[TypeZer0]

how well would the magnet wire from radioshack work for winding motors? btw, what makes magnet wire different from regular wire? is it just the thin invisible coating or is the wire itself different?

[neurokinetik]

It's the coating. The RS magnet wire would be fine. It's pretty cheap, too, though I doubt you'll be able to make good use of the 22 and 26Ga. There is enough 30Ga there for probably 10 or more motors, though.

[TypeZer0]

hehe...let's see how fast the stock fets burn up with a 20 turn 22gauge motor :D

[SuperDragon]

Neuro- How are you getting the amp the motors are you using a DMM to check this? Or are you doing some kind of math formula to get the best guess at the amp draw?


Also has any one thought of taking the stock fets and loading them on up on a board or leaving them in the car and smoking them but at the same time use a DMM to see at just what amps they burn up at?


SD

[TypeZer0]

he stuck an ammeter between the battery and the motor

[neurokinetik]

^^^What he said...

I use a DMM hooked up between a set of batteries and a motor. I am not testing these in the car using the ESC because I don't feel like ripping apart one of my setups in order to do it.

I can test current draw of the motor installed in the car, but it will still be from the standalone battery pack. Once the Tamiya speed checker gets here, I will be able to test the current draw under more realistic conditions, in a car, with the wheels actually turning something, rather than just spinning in the air.

[SuperDragon]

Did you hook the dmm in paralle or series with the bats?


Bat + ------ Dmm + ----- + motor
Bat - ------- Dmm - ------ - motor

or

Bat + ------ + Dmm - Dmm --- + motor
Bat - ------------------------------ - motor

SD

[neurokinetik]

Originally posted by SuperDragon
Did you hook the dmm in paralle or series with the bats?


Bat + ------ Dmm + ----- + motor
Bat - ------- Dmm - ------ - motor

or

Bat + ------ + Dmm - Dmm --- + motor
Bat - ------------------------------ - motor

SD

In series. That's the proper way to measure current. The way you have the second diagram drawn is the proper way.

Another motor to add to the list:

GPM Racing MH038 Modified motor (35 turns) 0.27A

This is a 180 motor. Made for high speed, but it also has way more torque than a 130. It jumps pretty good in your hand when you give it throttle. This particular model I bought online for $13. By ear, this motor is not as fast as a stage 2. However, with the blue gear set, I'm certain that it would own any stage 2 motor/gear combo on a road course. (Guess I should install it in the car before I claim that, though. :lol: )
Anyway, very low current draw, pretty much the same as a stage 1, so it will be safe for stock ESC, and give good run time whie offering good performance. It definitely doesn't sound as fast as the other 180 motor that I tweaked, though. Maybe I'll take it down to 25 turns and see how it does.

[TypeZer0]

oooooh, me likey, strong motor and no need for a FET upgrade :D

[neurokinetik]

Bought another of the Team Orion Elite Stock motors today. This time I actually ran a current check on it before ripping it to pieces. In fact, I even left it stock and installed it into my drag car.

Anyway, it draws a measly 0.21A. Very safe for the stock ESC.

I also consolidated all of my measurements into the top post of the thread, for easier reference.

[neurokinetik]

Updated the top post with Spin Brush results.

I also took that Plasma Dash armature that I rewound with 35 turns of 28Ga, and put into a shiny new Yeah Racing ball bearing motor can with some Yeah Racing thin Neo magnets. Sounds really nice. Need to test it in a car.

Current draw on that one is only 0.58A, same as a stock stage 2, but I'm thinking it won't be performing like one. :D

[Rez]

Are you gonna post some RPM stats?

[neurokinetik]

RPM stats will happen once I get my oscilloscope. I should have it this week.

So anyway, I just built me a FET killer motor. :cool: Pulls as much current as the Plasma Dash, and sounds very fast. It is my first double-wound 130 motor, it is a 2 x 21 turn. It is using spin brush magnets, and has the timing advanced, as usual. It is also in a Yeah Racing ball-bearing can. It pulls 1.7A with no load on it. Now I have to decide what pinion I want to put on it so I can test it in a car.

[Joey]

Alright, this has been bothering me since I started coming here: does a larger amperage draw necessarily mean a higher power output?

[TypeZer0]

would winding it twice at 21 turns effectively make it a 11.5 turn motor?

[mystiquesupra]

What size wire is on the sb motor and stage 1/2 motors?

Can these be un-wound, and then re-wound with the desired wind count with out damaging the wire.

Or is it best to use new wire from the start?

[Joey]

I don't see why there'd be any difference in using the original wire, as long as you took extreme caution not to damage it in any way. Short of breaking it, I don't even know how you'd go about hurting it anyway.

[neurokinetik]

Originally posted by TypeZer0
would winding it twice at 21 turns effectively make it a 11.5 turn motor?

It draws as much current as an 11.5 turn motor, yes, but generates the magnetic field of a 42 turn motor. Should give high speed and high torque.

Originally posted by Joey
Alright, this has been bothering me since I started coming here: does a larger amperage draw necessarily mean a higher power output?

Only if all other things are equal. Look at how low the current draw is on the 180 motors, yet they outperform every 130 motor I have made so far. In general, though, more power in should yield more power output from the motor.

Originally posted by mystiquesupra
What size wire is on the sb motor and stage 1/2 motors?

Can these be un-wound, and then re-wound with the desired wind count with out damaging the wire.

Or is it best to use new wire from the start?

SB Motor: 34Ga
Stage 1: 32Ga
Stage 2: 30Ga

You could re-use the wire, but it is harder to get it wound tightly when it has kinks in it from the previous use. Plus you will have to cut it where it attaches to the commutator.

[Vagabond]

The higher the gauge value meaning the finer the thickness of the wire right? I found some really thick gauge at the local tamiya store here in the Mini 4WD section and it's thicker than any wires use MiniZ and Xmod that i've seen. But there a thinner one on sale along with the armature, and the gauge is of silver. What's the differences between the silver and the copper wire?

[TypeZer0]

silver conducts electricity better but obviously it's gonna be a bit more expensive than the more common copper

[FastRSX]

neurokinetik where did you purchase the Yeah Racing ball bearing motor can?

[neurokinetik]

Originally posted by FastRSX
neurokinetik where did you purchase the Yeah Racing ball bearing motor can?

Dinball RC Mart.

http://www.rcmart.com/catalog/default.php?cPath=144_21_80

They have one motor can that just comes with ball bearings (probably one of the best cans, IMO.) but no magnets or brushes, and then they sell one that is pretty generic but has thin Neo magnets and carbon brushes.

As for motors wound with silver wire, well, that would certainly be interesting, not to mention expensive. In theory, you wouldn't need as thick a wire with silver due to the better conductivity over copper.

[neurokinetik]

Tried the 21 turn double in a car, and it was dissappointing, but not as bad as others I have tried (IE 25 turn single, Plasma Dash) On the speed checker, it hit 21kph, and that is with the 8 tooth pinion. Acceleration was not so good, taking at least 5 feet before it really started to move. Oh yeah, and that is also after I swapped out the spin brush magnets for thin Neos. The motor runs quite hot, and the FETs started heating up after a minute or so as well.

Oscilloscope will be here tomorrow, but I'll be too busy racing to do RPM testing. Hopefully Thursday night I'll get cranking on that.

[boxcrash]

I have a Oscilloscope at work on the test equipment as well as many other tools, all digital as part of our Seimens Diag equip.

I have not even tried to use it in this way yet but have planned to, maybe now I will get onto that.

Also I am curious as to what the magis ESC current draw number is and I know no one knows....anyone know a engineer who helped create these or is there anyway to find out???

[neurokinetik]

I suppose it could be found by sacrificing a couple of the stock FETs. Run for about 30-40 minutes at a set current level, if they don't smoke, let them cool off and start again at a higher current level. Repeat the test until they smoke.

You'd need access to a regulated power supply with an adjustable current limiter. Run the FET output to a very low impedance load, and use the adjustable current limiter on the supply to set the current level.

I don't have such a supply at the moment, and have no great need to buy one. Plus this testing would be time consuming.

[boxcrash]

true that would work and require alot of time.....

Not that I want to fry some FET's up though.

Have you ran the stock Plasma Dash on a stock XMod for a long time??

I have a motor I am curious about that when measured on 10amp scale pulled a steady no-load .70 amp(700 miliamps) @ 8.5v aprox on a 9v battery that was at 8.8v before load test.
It did jump to 2.0 amp max when the juice was first applied to it and leveled off at .70 consistently.

Just wanting to find out if this thing will be a stock FET smoker.:D

[ahedofu]

neurokinetik

this is kinda of topic but isn't rcmart in hong kong.

I was wondering how long it took the cans that you ordered to get the states (to your house)


Thanks
Richie

[boxcrash]

Crap.I typed a book........ and accidently changed the page before I hit submit...

Ah well I used a primative method to check the motor I have described above for RPM's at 3.6v.
A microphone and my computer using Sound Forge.

Recorded the motor spinning and clicking a piece of flexiable plastic against the pinion in a homemade motor stand @ 3.6v.
I counted the + in the waveform in the software at .100 seconds which I multiplied by 10 then multiplied by 60 then divided by 8(number of teeth on test motor pinion).
Which gave me 24,225RPM's under no load other than that small plastic piece.
So @ 7.2v I would have 48,450 RPM's under no-small load.

Which is about right because I tacked down manufacters motor site and used there graph and specs and got 7.2v=48,600 RPM's at 25* C which RPM's and efficency increase with tempature up to 80*C. Which I imagine like computer after that it drops and you have looslesness or whatever and loose gains. Like the 130's feel like 130*C + under 30 minutes load so I know there is lose.:D :rolleyes:

yeah so anyhow that seemed to give me a roundabout aproxmation of RPM's. I might still get a laser meter.:D

And yes RC Mart is in Hong Kong and I have heard it takes 4-8 days to get a package from them.

[neurokinetik]

Originally posted by boxcrash
true that would work and require alot of time.....

Not that I want to fry some FET's up though.

Have you ran the stock Plasma Dash on a stock XMod for a long time??

I have a motor I am curious about that when measured on 10amp scale pulled a steady no-load .70 amp(700 miliamps) @ 8.5v aprox on a 9v battery that was at 8.8v before load test.
It did jump to 2.0 amp max when the juice was first applied to it and leveled off at .70 consistently.

Just wanting to find out if this thing will be a stock FET smoker.:D

Plasma Dash WILL FRY YOUR STOCK ESC! With a set of four NiMH AA's, it was drawing 1.7A continuous. The Mini-Z guys all stay away from it now after melting both FET stacks and extenal turbos with it. I ran one in my car for a minute, but the performance was so poor in an XMod that I scrapped it for parts pretty quickly.

Using a 9V to measure current is not a good idea, as they don't put out the kind of current that a set of NiCd or NiMH AA or AAA batteries do.

[Mr BigShot]

Just a Quick ? It maybe a dumb ? also but in my Highly supped up "Team Orion Big Block supra "i still have stock Fet's if i stack 2 or 3 Fet's will that make it a lot faster ? It all ready fly's but more speed is all ways better :D

[neurokinetik]

You probably won't see much difference in speed from a FET stack.

[boxcrash]

Originally posted by neurokinetik
Plasma Dash WILL FRY YOUR STOCK ESC! With a set of four NiMH AA's, it was drawing 1.7A continuous.

Using a 9V to measure current is not a good idea, as they don't put out the kind of current that a set of NiCd or NiMH AA or AAA batteries do.

Yeah I know a Plasma will pop FET's like candy. Its not a Plasma I am testing, it is something else.

Yeah I only had a 9v at the time, I do realize the maH is much less and all that jazz.
I was only using it for purposes, I plan to use some recharges and see what I get.
Just curious will a quick spike of 2amps be ok and a sustained of about 600-700mAMPs fly with stock FET's???

Yeah thanx.