Spaceclam

Will impregnating the windings with heat sink compound allow me to run more power through my motors since it is more conductive than air, or will it decrease my power handling ability since there is no air FLOW over the windings?

also, what is copper loss? is that why people use 22.4v packs, so you can have more turns of smaller wire, resulting in more copper? how serious is the effect?

Alan Hahn

I am not sure about the heat sink stuff---it is used to conduct the heat to something that can absorb or radiate the heat away, so you need to figure out where you are trying to put the heat---the stator? and does it shed the heat better/faster than the copper itself.

Copper loss is just ohmic heating. The heating or the wire due to its resistance is just I*I*R, where I is the current and R is the resistance of the copper.

First understand that the ohmic heating is only dependent on the total copper in the windings, not the number of turns. So fewer turns with larger gauge wire and a higher current will have the same heating a more turns of thinner wire for the same amount of power going into the motor (this is Power=I*V). So higher Volts and lower current will give the same amount of resistive heating as higher current and lower voltage, as long as the product of volts and current is constant.

Spaceclam

I love it when you get confused over a term that describes something you already know [:@]

cyclops2

You really know how to pick tough questions that can have several correct answers.
All the questions have, " maybe " answers.

1...Impregnating windings.
They need the conpound in the hottest part of the winding. The center of the slot and the side opposite the prop. That should have compound laid in before winding starts and added as winding is done. Then remove all excess. HOWEVER. As the motor runs at top speeds the compound WILL flow out ward and possibly unbalance the rotor. It will definately fling out and make a mess that blocks any airflow thru the center of the motor. It can even cause a sliding drag. This is in a rotor with windings.

In a RC brushless we still have a metallic grease that can thin out and slide out of the stator slots and fill up the bottom 1/3 of the stator to rotor air gap and cause a drag.
I would not do this idea.

2..Copper losses can be outrageous on 3 volts compared to 30 volts...A heating up of thr copper wire at full power causing a 1/4 volt drop more than at a cold start, is a big loss at 3 volts.
Since people push the motors OVER the rated powers. I-R copper losses can be huge due to overheating the center wires in each slot of the rotor.
You are right about using higher voltages for the motor.
The same possible heating losses can also occur in the battery cells. It is called the C rating and shows up as a dropping of voltage. High currents cause heavy wires to be used. ETC.
Real electric motor manufacturers always shoot for high voltage.


Another reason for high voltage is that cells of 1 to 2 amps can be wired up in series for little $$ to get any wattage.

Spaceclam

so then, if i had a lot of stator poles, (24) and only wound 8 turns (enough to have exactly one layer of wire, 17 awg btw) than my motor will be able to handle much more power, due to more effective and even cooling?

Also, if i had some stators that are going to be stacked, but need to be insulated, what's a good material to use? i need something really thin... perhaps a coating?

cyclops2

I can not help on rewinding.
I am a specialist. I only burn them open.


Rich