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Electric EZGO Electric EZ GO Marathon, Medalist, TXT and RXV. |
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09-09-2021, 11:16 AM | #11 | |
Gone Wild
Join Date: Jan 2013
Location: Saint Petersburg, FL
Posts: 2,089
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Re: Anyone have D&D high torque motor?
Quote:
What is it you are wanting more of? |
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09-10-2021, 09:06 PM | #12 |
Not Yet Wild
Join Date: Feb 2016
Posts: 22
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Re: Anyone have D&D high torque motor?
I just figured with the extra torque it wouldn’t slow down as much on hills (granted I have some steep hills around my place). Now with a better understanding of the fact it’s still going to slow down a lot (2-3mph) but it won’t stop (even if it feels like it might), I’m ok with it.
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09-11-2021, 11:17 AM | #13 | |
Techno-Nerd
Join Date: Jun 2011
Location: West Virginia
Posts: 19,654
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Re: Anyone have D&D high torque motor?
Quote:
All electric carts slow down on inclines. AC drives slow the least and series drives slow the most with sepex drives somewhere between the two extremes. The amount of torque torque produced by the motor is determined by the number of amps flowing through it and the amount of amps a motor is capable of drawing is determined by the RPM it is spinning at. Due to back EMF increasing as the RPM increases, the amount of amps the motor is capable of drawing decreases as RPM increases, therefore the torque decreases as RPM increases. The only thing a controller can do is limit the amps it is passing from the battery to the motor, so at WOT, the controller (if its throughput exceeds the motor's max amp draw at stall) ceases to exist in the circuit. On level ground the cart will accelerate until the motor reaches the RPM at which the amps it is capable of drawing at that RPM produces an amount of torque that is equal to the load (mechanical drag) being imposed on the motor. That is the cart's top speed. When a cart traveling at its top speed encounters an incline, the mechanical drag increases since the cart's weight has to be lifted against gravity. At this point the mechanical drag is greater then the torque the motor can produce from the amp flow at that RPM, so the motor slows until the motor is again capable of drawing the amps needed to produce an amount of torque equal to the new load being imposed on the motor. The attached chart show a typical series drive motor on a dyno. It is powered from a 48V source whose voltage is reduced 1.5V per 100A of current draw to emulate a lead-acid battery pack performance, other than that it is WOT. The dyno loads the motor down until it is producing close to specific torque levels and shows the RPM that torque level was developed at as well as Volts applied to the motor, Amps drawn, Electrical HP input, Mechanical HP output and calculated efficiency. As you can see, this specific motor can draw over 500A when spinning at about 1000RPM with about 80ft/lb of torque being produced, but can only draw about 50A at about 4300RPM with about 3ft/lb of torque being produced. Other motors will have different numbers, but the generic RPM vs Torque vs Amps relationship will be the same. |
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