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Electric EZGO Electric EZ GO Marathon, Medalist, TXT and RXV. |
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07-25-2010, 03:34 PM | #1 |
Gone Wild
Join Date: Mar 2010
Location: So GA
Posts: 237
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Voltage increase & Gear Ratio decrease effects on Torque
If I move my cart from 36v to 48v there will be an increase in speed and torque. If I reduce my gears from 12.44:1 to 8:1, I will lose torque. If I do both will the torque be a wash or is the gear drop going to cause more torque loss than the 12v increase raised it?
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07-25-2010, 05:02 PM | #2 |
Gone Wild
Join Date: Jun 2010
Location: Central Florida
Posts: 2,757
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Re: Voltage increase & Gear Ratio decrease effects on Torque
I had this same question the other day and Scotty and I were discussing it. Judging on the motor you have, the prevailing theory is that you should increase torque more than you will lose with the hi-speed gear set.
We'll use you for the guinea pig though...... I have the gears if it's for the cart you have in your avatar, let me know if you want to buy a set. |
07-25-2010, 08:43 PM | #3 |
Gone Wild
Join Date: Mar 2010
Location: So GA
Posts: 237
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Re: Voltage increase & Gear Ratio decrease effects on Torque
Rabbit, that is the cart, a '96 medalist. I'm kind of pushing the envelope with the 2 speed EMP motor I have. EMP doesn't recommend 48v conversion without a reupgrade (rebanding) nor do they recommend high speed gears with this setup. I'm planning on leaving it in torque mode most of the time, which basically is a stock motor (well much better than the actual stock motor). Approx. 3750 rpm (17-18mph), so 48v should take me to 5000 rpm (24mph) and hopefully I'll have enough torque with the 400amp controller to handle the gear change, 8:1 = (35mph w/19 inch tires). I think I'll just have to be careful in speed mode, which is turning approx. 5500 rpm now (26mph) and would be near 7400rpm (34-35 mph) at 48v. Lots of heat in speed mode, I think that is why they like no more than 400 amp with their setup. I'm mainly always on flat ground, road or course, no hills, so I'll try not to start out in speed mode or overuse it. The crazy thing is if the speed calculator is near correct, in speed mode with 7400 rpm/19in tires/8:1 gears = 52mph???? Could that be correct? Anyway, Rabbit PM me your best deal on the gears and we can get some actuals on this!
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07-25-2010, 09:12 PM | #4 |
Gone Wild
Join Date: Jun 2010
Location: Central Florida
Posts: 2,757
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Re: Voltage increase & Gear Ratio decrease effects on Torque
PM sent.... I just realized however that the set I have is the 6:1 set, not the 8:1 set.
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07-25-2010, 09:25 PM | #5 |
Stay thirsty my friends!
Join Date: Jan 2007
Location: Suburban Chicago
Posts: 24,283
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Re: Voltage increase & Gear Ratio decrease effects on Torque
BTW, the formula is correct IF you have the horsepower to achieve those RPM's.
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07-25-2010, 09:29 PM | #6 |
Gone Wild
Join Date: Mar 2010
Location: So GA
Posts: 237
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Re: Voltage increase & Gear Ratio decrease effects on Torque
10-4, gorno. I don't know what I have, probably a granade waiting to happen! I'll have the 48v by the end of this week and I'll see what the numbers are, then I'll try the 8:1 in the near future.
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07-26-2010, 09:16 AM | #7 |
Gone Wild
Join Date: Nov 2008
Location: Montgomery, AL
Posts: 1,463
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Re: Voltage increase & Gear Ratio decrease effects on Torque
also can that motor handle the 5000+ rpm you are planning on spinning it?
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07-26-2010, 09:51 AM | #8 |
Gone Wild
Join Date: Mar 2010
Location: So GA
Posts: 237
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Re: Voltage increase & Gear Ratio decrease effects on Torque
Courtesy, I'm going to find out. I think I will be fine at 5000rpm in torque mode, 7400rpm in speed is getting on up there and probably will cause problems if I abuse. The unknown is how EMP does the speed mode, it is basically a shunt, I have an extra two poles on my motor and it reverses polarity to go into speed mode (heats up fast, torque is poor in speed). I don't know what the gear change will do to the RPM's because, like G-man said I need the horsepower to continue to turn those RPM's at 8:1. I'm going to test the limits of this motor, but in the long run I'm going to change to a PQ motor and different controller.
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07-26-2010, 10:52 PM | #9 |
Gone Wild
Join Date: Jun 2010
Location: Central Florida
Posts: 2,757
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Re: Voltage increase & Gear Ratio decrease effects on Torque
The 400 AMP controller isn't the issue.... 400AMPS is typically more than enough. The big unknown is that EMP motor.......
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07-26-2010, 11:09 PM | #10 |
Gone Wild
Join Date: Oct 2007
Location: Snellville, Ga.
Posts: 1,304
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Re: Voltage increase & Gear Ratio decrease effects on Torque
I have an EMP 2 speed motor on my cart. I have run upto 72v through it without grenading. I only ran a short while at that voltage. I didn't check for motor heat. I had motor hard wired on the speed mode. I do not have a gps but there was a stong wind in my face. My cart is old (82?) and cart was unstable at those speeds. I am happy with speed at 48v.(p.s. I had the extra banding installed on motor).
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