madin88 said:
ElectricGod said:
Regarding the 80-100 outrunner motor size. it is possible to buy after market magnets that are much stronger, but after owning several of this size motors from various sources, they all have N35 magnets. Go ahead and throw 100kw into the motor. It won't matter. You can only pull on the magnets at their maximum strength and not more than that. More wattage, even peak is only useful up to the magnetic strength and then it's just pointless.
You won't get higher
peak power out of your motor if you install stronger magnets.
The only thing this would be useful for is if you want more torque in exchange for RPM (trading RPM for torque), nothing else.
And wattage practically means nothing for the magnetic circuit. It is the current in the winding which is relevant for that.
READ what I wrote rather than skimming.
I mentioned stronger magnets in terms of magnetic torque. If you want to make the motor stronger, put stronger magnets in it...and of course rewind the stator for max copper fill.
Just throwing more current into the stator and you are already pulling on the magnets AT their maximum capability will NOT create more torque. It's just a waste of power and a great way to make heat.
Peak power is only useful IF it is within the limits of the magnets ability to create magnetic torque. Peak at 10kw on magnets that can hold against 3kw and your motor won't make 10kw of torque. It will make 3kw of torque and 7kw of heat!
Watts = volts x amps
What you say about watts not mattering? It's a relationship between the voltage and the current in the motor. As an experiment, get an RC ESC good for 1S or 4.2v, Beef up the mosfets on it so it can deliver something like 200 amps. Now run your motor at 4.2v and 200 amps. Lets see that baby run at 840 watts! Now put it on your 82v set up at 10 amps. I know which set up I want and it's the 82v/10A one! The motor will do MUCH better at higher voltage and low amps than it will at the same wattage at very high amps and almost no voltage. It is a relationship of both voltage and amperage, not just one without the other. AKA watts DO matter as it is an expression of that relationship.
I used to work on industrial 2 and 3 phase breakers. The little ones were 600 amps. The biggest one I worked on I stepped inside it to work on it...several thousand amps and it arrived at my shop on a semi trailer and nearly maxed out the weight limits of the truck! We had to rent a special crane just to get off the trailer bed. After I refurbished it''s contacts and re-calibrated its current sense coils, I then tested it on a special tool we had. It ran at 1v and could deliver many thousands of amps. You could put your wet hands on the main power posts at max amps and not die. So much for all those amps and no volts! You really need both.
Let's ask a different question. Which set up will make the most heat in the windings? It's current that creates heat, not voltage. AKA the 4.2v, 200A set up will heat up the motor more. Don't believe it? Do you know what a taser is? It's a high voltage low current power supply. The wires from the probes to the gun are very thin...something like 32 awg. IF there was more than a few milliamps on those tiny wires, they would heat up instantly and burn out. They do have several thousand volts on them and suffer no damage.
Back to that "peak" question which was from the video where the guy titled it 15kw blah blah blah. In the video he says he has 80-100 outrunner. What a total joke! Even IF he rewound that stator for max copper fill, he would still maybe get 7kw of useful power WITH stronger magnets too. with the factory N35's in it probably 1 or 1.5kw of that would be useless since the N35 magnets can't deliver more magnetic torque to react with the 7kw of torque in the windings. 15kw really? I'm not that gullible.
Again..peak is pretty meaningless. You can only pull on the magnets AT their maximum magnetic torque and no more. How about just set up your controller so it's phase amps are at whatever gets to that maximum magnetic torque? In that case, I can probably run all day long like that. Oh wait...that IS exactly what I do.
For anybody that cares, the Alien Power C80100...one of many 80-100 outrunners...is quite strong. I have one on a 75 pound stand-up scooter. I'm not exactly light at 240 pounds. Never the less at 66v, that "toy RC motor" hauls me around at a tidy 45mph top speed and I accelerate better than the cars do. I'd call that motor quite usable on an EV. Anything more than like 6kw is just laughable! It gets way too hot to pull off more than 5kw for more than a few seconds. I know, Ive seen what 6kw does to it!