Rewinding motor...(updated) page 3 Auto Wheelie

hillzofvalp said:
how does one rewind a motor well? how long does it take? I wanted to try putting a few more turns on my 9x7... can I just add some on or do I have to start over completely?
Was it you gord sent me an email about?
#1 colossus took me from 7:30 am to 1:30 pm strait and my hands hurt for days! (Yours will take longer!!!)
#2 rewinding to add turns WILL NOT GIVE YOU MORE TORQUE!!!! The only time you get more torque is if your controller is limiting the amps to much.
#3 This will make a less efficient system!!!
 
There is absolutely zero room left in the slots on a 9C to slip anything else into.


Rewinding one from scratch (the HX35 I did) took roughly 10hrs of experimenting to find the optimal wire gauge, number of strands etc. The winding process took about 20hrs of very surprisingly hard work.

If I had to make a bid for what it would cost to have me re-wind a hub, I wouldn't even consider it for under $1,000 labor.

Justin told me the ladies in China who gather around like a quilting party and wind these motors are incredibly fast and good at it, and do like 10 of them a day or something insane like that. I can't imagine even doing 2 in a day, my fingers were all raw after just finishing one. lol
 
Also, we played with various wire fill calculators to see what was possible, and tried to shoot for that. OMG fail. I think something like 70% was possible in the calculator, we got like 55% or something jamming everything down as tightly as possible with chop-sticks and anything else we could dig up. The wire fitment calculators had no bearing on reality IMHO.
 
hillzofvalp said:
Yeah I want more torque. What about lower gauge wires?


The number of turns is 100% irrelevant to the amount of torque a motor can produce.
 
hillzofvalp said:
Then why is it that in the rc car world it was thought that higher turns were better for offroad and acceleration?
They are limited but the amp limits of their controllers!
 
liveforphysics said:
The number of turns is 100% irrelevant to the amount of torque a motor can produce.
doesn't increasing the number of turns (by using smaller wire, but keeping the same fill %), result in the same power, just at a lower rpm? and wouldn't that be considered an increase in torque?
Arlo1 said:
#2 rewinding to add turns WILL NOT GIVE YOU MORE TORQUE!!!! The only time you get more torque is if your controller is limiting the amps to much.
ok, i now i'm a noob, but this doesn't make much sense. i could see if the VOLTS were being limited, and the resultant INCREASE in amps, to match the load, resulting in, again, the same power, just lower rpm, ergo, higher torque.

what am i missing guys?
 
hillzofvalp said:
And what's the difference between HT and HS motors?
Hs is wound for High Speed Ht is wound for low speed. This only makes a difference in torque if you have a elcheepo uber low phase amp controller!
 
Its the copper fill that determins the torque. More windings at the same copper fill % reduces the speed, and allows the motor to opperate more efficently at lower speeds under load, but the ultimate torque stays the same.


In the RC world, there are 2 ways a higher wind motor might be considered a torque motor. First, and most likely is it simply has more windings with the same copper fill, and is meant to be used at low speeds without overheating. calling it a torque motor simplifies the explination but isn't accurate. The ultimate torque is the same, its just being produced diffrently.
The second but less common is to actualy have less copper fill in the speed motor. That reduces the weight and can let the motor hit even higher RPM than just the winding count alone, although the ultimate power is reduced. Its been more than 25 years, but I think Tamaya did it that back in the day with the 380 and 540 series brushed motors.
 
The current in the conductor determines the flux produced by the conductor. It is always directly linear, if current doubles, flux doubles, and a conductor itself has no saturation limits, if you can put the current through it without melting, you get the full and exact amount of flux for every amp you applied.


Each turn around the tooth captures the flux from the wire, and creates the flux in the end of the tooth that interacts with the magnet.


If you have 20 turns and 5amps going through them, you end up with the exact same flux as if you had 10 turns with 10amps going through them, or 5 turns with 20amps going through them.


Likewise, the heat generated per amount of torque is exactly the same, as heat is resistance * amps^2, and the resistance increases at the square of turns (because to double the turns, you have to make the wire both twice as long as well as half the thickness).


The single thing that effects the continuous torque production of a motor is the % copper fill in the slot.
 
luke i bet you are the busiest person on this forum, but at some point I beg you to find the time do a simple write up of your experience with rewiring that hs. Even just a page with your thoughts, experiences and the gear choices you made would be infinetly helpful. Full hub motor rewinds are the one thing that is essentially undocumented online; i have searched for it. There is a GM rewind vid on youtube, and I know that guy with the Tesla avatar has rewound a couple, but there no one defining post explaining the wire, the calculations, the stator lining paper, the winding pattern, the tools required, the process, the tips and what not to do... I know some of the basics of what you did are outlined in the pre buy motor thread, but the full experience would be invaluable.
 
I'm the guy always saying slower motor winding for hills and off road. I'm not saying you have more torque or you have more power. I just got better educated on another thread about how much power I can expect to get from my particular 9 continent motor. It's not that much power.

But here is why I think it works for me. The low speed motor simply tolerates the slower speeds you get when you climb steep stuff. So the same 1500 watts or so I can get out of that motor can be used at slower speeds. It's not more power, or more torque. It's just less stalling of the motor when going slow. So when I ride up a steep hill with 1500w feeding a 2812 winding at 10 mph, less of that 1500w is making heat than would be the case with a 2807 winding. That means more power that reaches the rubber under that particular condition, and feels more torquey. On the flat, less difference in the power because now the fast winding is not making more heat. On the flat, the fast motor seems to be better.

You can buy the slow motors pretty cheap, from Methods. Not laced in the rim you like, just swap the insides and the covers. The magnet ring is the same, even between the new style and old style motors.

For sure though, you can't pack more copper into those motors than the china lady does. They are truly amazing!
 
I always like high speed motors cause they can generate more torque on the top end. They pull very hard if you feed them the current they want. Low speed motors that choke on bemf and feel very amemic but the acceleration is awesome ... Yaaaay!! awwww......

But if both motors are on the same voltage and amperage neither has more torque... Their power bands are just in different areas and one just happens to be faster but it will take a long time for it to top out in speed since the controller is limiting it.
 
Instead of a rewind that won't do much of anything other than change the rpm/volt, invest in a better controller with programming flexibility to maximize your motor's performance in your use. Yes more turns on the winds give lower rpm and more torque for a given current and voltage, but less turns can handle more current before producing the same heat, so it puts you back in the same boat in terms of torque. Power is rpm X torque, and since our current is variable up to what these motors can handle, then max torque is identical. We are, however, practically limited in voltage, so the lower turn count motor is capable of more power.

If you really want more torque with a hubbie, then use a smaller wheel. If you're not at 100V yet, then increase voltage to get back to the top speed you want. Then you have more torque at the ground, and more power too, and that's before raising the current limit. The higher rpm even means better cooling for any given speed, so while some get stuck on the idea that 26" wheels are mandatory, they miss out on real performance.
 
I have a 29er. The point is that the wheels need to be big. My controller is a 12 FEt lyen edition.. it's got a lot of programability and capability of being modded.

I WANT MORE ACCELERATION. I don't mind topping out at 30mph. Acceleration is what counts.

How about this: buy a 2810/12 stator/motor.. swap out stator to my current wheel. go from 46.2 to 66-100V. Won't I see less heat?
 
hillzofvalp said:
I have a 29er. The point is that the wheels need to be big. My controller is a 12 FEt lyen edition.. it's got a lot of programability and capability of being modded.

I WANT MORE ACCELERATION. I don't mind topping out at 30mph. Acceleration is what counts.

How about this: buy a 2810/12 stator/motor.. swap out stator to my current wheel. go from 46.2 to 66-100V. Won't I see less heat?
So my advice to you is a slightly bigger controller. I have pushed my modded 12fet at 84v to over 90amps but I dont sugest it. It seems to be happy and not get to hot in the 40-60 amp range!
An 18fet controller will be more then enough for you to pour more amps into the motor. If you know the settings of your 12 fet you should let us know. Because if you are at 20-30 amps during accel then you can up it a bit and maybe be happy.
With a big wheel you are using a lot of amps and just making the motor hot this is the problem with hub motors in big wheels! But John is right Smaller wheel = more torque! This is why I will never run a hub motor in anything over a 20" wheel!
 
that will never happen with this bike. I want it to have big wheels cause I love it that way. I've had it at 55A and 120A phase.. but I want more. I am considering 66V and 75A, but I bet that will toast my motor.
 
Bursts of big power for strong acceleration is unlikely to make a problem with overheating. It is prolonged high loads such as long steep hills at high power low speed or high speeds on the flat where big power is required, that will cause overheating problems.

Winding a motor is not easy, you don't want to do it :) The small multiple parallel wires that are used in the 9C aren't so bad, but using heavier gauge wires is tough on the hands.
 
Andje said:
luke i bet you are the busiest person on this forum, but at some point I beg you to find the time do a simple write up of your experience with rewiring that hs. Even just a page with your thoughts, experiences and the gear choices you made would be infinetly helpful. Full hub motor rewinds are the one thing that is essentially undocumented online; i have searched for it. There is a GM rewind vid on youtube, and I know that guy with the Tesla avatar has rewound a couple, but there no one defining post explaining the wire, the calculations, the stator lining paper, the winding pattern, the tools required, the process, the tips and what not to do... I know some of the basics of what you did are outlined in the pre buy motor thread, but the full experience would be invaluable.

There's a good site for rewinding RC motors with lots of winding diagrams etc:

http://translate.google.com/translate?u=http%3A%2F%2Fwww.powercroco.de%2F&langpair=de%7Cen&hl=en&ie=UTF-8
 
What kind of riding on the 29 er? What are your doing, street riding on flat, street riding with hills, or riding slow on steep or twisty singletrack trails?

I'm loving my 9c 2812 bike, but at 72v I only have 25 mph speed. That's fine with me because the mile or less of road to the start of the trail goes plenty fast at 25 mph. Then I'm riding below 10 mph for the rest of the twisty dirt trails, with occasional full speed blasts down dirt roads to other trails.

If you want 30 mph, and aren't actually riding up dirt hills at 10 mph, I would suggest the 2810 winding and 72v. Then limit amps to about 30. John had a fun time the other day showing me how too much watts into the 9c motor was a waste of time, at least in the slower windings. I'm starting to get it, where the watt limit for a 9c motor really is. When I ran 72v 40 amps through a 2810, I did melt the motor fairly quickly by climbing too many steep hills. I mean really steep, like 25 degrees, degrees not percent. Too much wattage avalible to make heat basicly, so when I started stalling it, it just made mega heat. Sticking closer to the wattage the motor can actually use is a good idea.

Heres a 2810 at 72v thread.
http://endless-sphere.com/forums/viewtopic.php?f=3&t=21390
and my 2812 thread
http://endless-sphere.com/forums/viewtopic.php?f=4&t=27364
 
yeah,, I am mostly flats with a max elevation change of 500ft over 15 miles. STreet riding. I have cooling holes in my 2807 as well as 12 gauge deans phase wires. Let me know what you think it can handle for burst accelerations. This is a college town, so there are people to avoid and starting and stopping,

I will beef up the traces soon...
 
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