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Just hooking it up to a higher voltage can deliver more current than the motor is rated for. That will reduce the lifespan of the motor and, if the current is high enough, cause it to fail.
However, there are a number of separate issues with DC motors.
Over Current. As I mentioned above, too high a current will overheat the coil and if it gets hot enough, it will burn out or seize the motor. Too much current can also affect the magnetics in the stator.
Over voltage. The windings in the coil have an insulation rating that will fail if the voltage is high enough causing arcing and again, burn out. Further, the brushes will arc more at higher voltages causing heat and faster wear.
Over speed. DC motors are not the best mechanical beasts in the world. Brushes rubbing on the commutator and often poor bearings means over speed will significant reduce the lifespan of the motor.
Having said all that, the number one issue is over-current.
CONTROLLED OVER-DRIVE
Motor rating plates are defined for a static..."Apply a voltage and go" setup.
If you limit the current to the motor you can in fact drive it at much higher voltages and speeds without significantly over-heating the motor.
This is because one of the governing factors of the current taken by a motor is the speed of the motor itself. The back EMF generated by the motor as it spins reduces the current you can deliver at any given terminal voltage.
In theory, if say the rated current of the motor is 1A, and your motor drives the load at max speed using less current than that, it is possible to increase the terminal voltage, and hence the speed, until the point where the rated current reaches that 1A level. This must of course be done while limiting the current to that 1A value.
However, there are limits to this. Obviously you can not exceed the breakdown voltage of the coil, but also you have to remember there are switching inductors inside the motor. These form an impedance that increases with motor speed. As such the max current becomes harder and harder to achieve with speed within a commutation cycle. Also, the motor may mechanically destroy itself at extreme speeds.
EXTRA COOLING
The other thing you can take into account is cooling. The motor will be specified at a certain ambient free flow air environment. If you can increase the air-flow over the rotor or otherwise extract heat from the core, you can in fact drive the motor harder with little significant effect on the motor other than reduced brush life.
YOUR MOTOR
Unfortunately E-Bay is a terrible place to buy stuff. Specifications and data sheet links are usually non existent. So knowing exactly what no load current = 3A is supposed to mean is anyone's guess. Plus, what you get in the mail is not always what's shown on the site. However, at <4$ a pop....
First I just want to say if I got any facts wrong please feel free to correct what I said.
So I’ve been meaning to start this for awhile now. With the new Stormcore 100D and Rion Tronic coming out a lot of people are moving to higher voltage. What we are missing is a motor that’s not a crazy low kv (90kv Maytech) but also supports the amperages we want.
So back story on why you might want to run higher voltage on your board.
SummaryThe main thing (in my mind) is more speed without a decrease in torque. We all know upping your gearing so you can hit higher speeds makes your torque drop away. Higher voltage solves that by adding speed by putting more volts into the motor making it spin faster at the same gearing.
Another reason to go higher voltage is the torque. 16s 100amps per motor will be more torque then 12s 100 amps per motor. This is a big thing if you live in a hilly area or just love torque and take offs.
Finally, efficiency. The higher the voltage the more range you will get. A 13s4p battery will get more range then a 12s4p battery, if the same cells are used and you were to ride both batteries the exact same. For example (hypothetical so not true but gets the point across) A 13s battery at 60amps will feel the same torque (if geared for the same top speed) as a matching 12s battery with 70amps being used. This means the 13s uses less power to reach the same torque and top speeds as the 12s battery which leads to a better mpg aka wh/mi or wh/km.
Alright, on to the real point
So here’s the real point. We don’t have motors that can do these voltages. Alright yes we have motors built for cars like Nissan Leafs and Tesla’s, but those don’t fit our application.
Really speaking, we can’t get those motors we want without buying in a large quantity.
For example I was all set to do a KDE Motor Groupbuy (suppliers of Hoyt motors) for custom made 63100 25s 250a rated motors. These would’ve been the bees knees, but they cost $386 dollars per motor. Now you might be saying, “Hey that’s pricy but if it lives up to its expectations then why not?” Well I’ll tell you why.
KDE wants $2250 as payment for the custom motor design and tooling etc. This means that if we bought 20 motors (10 sets) it would cost $498.5 per motor excluding shipping. If we sold/bought 24 sets (48 motors) it would cost
~$438 per motor. In my head I knew that personally, I’d sell stuff and I’d buy 2-4 motors at that cost. But I knew that seriously speaking, we wouldn’t make up that other 44-46 motors.
The point of this thread was so that we could help each other and try to find or have made a motor that fits all our high voltage needs.
Big shoutout to @ahrav for proofreading this mess of words