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Electric EZGO Electric EZ GO Marathon, Medalist, TXT and RXV. |
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08-20-2016, 07:38 PM | #1 |
Getting Wild
Join Date: Mar 2016
Location: Lahaina, HI
Posts: 75
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PDS Cart Poor Torque, New Motor
There was a similar thread on this Board with lot's of suggestions but the person who had the problem never posted to let us know if he ever got his cart fixed and what solved the problem
I have a EZGO PDS cart (2008 ) that has been upgrade, but has very poor performance on moderate hills. It is a 2 passengers unit with stock size wheels but has been upgraded as follows. 1. Converted to 48 volts. 2. Motor replaced with AMD EY7-4001 (3268 ) high torque motor. Field map set to D1162E-Fm-55.HEX. #2 Gauge wires, new 48 volt heavy duty solenoid with diode and resistor for 48 volt. I originally had the DCX400-PDS controller and just replaced it with a DCX500-PDS, with zero improvement in performance. I just tested the cart while creating a log file. TimeStamp,ThrottlePos,DiodeTemp,BatteryVoltage,Out putCurrent,BatteryCurrent,ErrorFlags 08/20/16 13:38:00.469 0,33.0,49.8,0.0,0.0,0x00 08/20/16 13:38:05.477 19,33.0,49.7,0.0,0.0,0x00 08/20/16 13:38:10.484 100,33.0,45.5,150.0,150.0,0x00 08/20/16 13:38:15.492 100,33.5,46.5,94.0,94.0,0x00 08/20/16 13:38:20.499 100,33.0,45.9,112.0,112.0,0x00 08/20/16 13:38:25.507 100,33.5,45.4,145.0,145.0,0x00 08/20/16 13:38:30.499 100,33.0,45.3,150.0,150.0,0x00 08/20/16 13:38:35.522 100,33.0,45.1,155.0,155.0,0x00 08/20/16 13:38:40.514 100,33.5,45.1,164.0,164.0,0x00 08/20/16 13:38:45.537 100,33.9,45.2,150.0,150.0,0x00 08/20/16 13:38:50.529 100,33.9,45.2,141.0,141.0,0x00 08/20/16 13:38:55.553 100,33.9,45.8,122.0,122.0,0x00 08/20/16 13:39:00.545 0,33.5,49.0,0.0,0.0,0x00 08/20/16 13:39:05.552 84,33.0,47.0,117.0,98.2,0x00 08/20/16 13:39:10.560 100,33.5,45.1,159.0,159.0,0x00 08/20/16 13:39:15.583 100, 33.5, 44.5, 178.0, 178.0,0x00 08/20/16 13:39:20.591 100,33.5,45.0,155.0,155.0,0x00 08/20/16 13:39:25.598 65,33.0,48.9,0.0,0.0,0x00 08/20/16 13:39:30.590 100,33.0,45.1,159.0,159.0,0x00 08/20/16 13:39:35.598 100,33.5,45.0,155.0,155.0,0x00 08/20/16 13:39:40.606 0,33.5,48.9,0.0,0.0,0x00 08/20/16 13:39:45.629 0,33.5,49.1,0.0,0.0,0x00 The log file shows a maximum Output current and maximum Battery current of 178 amps (going up a moderate hill that has slowed the cart to about 8 miles per hour). Doesn't that seem very low for a 400 amp, or 500 amp, controller? Am I correct that under heavy load and if everything is performing correctly, the Output current should approach 400 amps for the DCX400 and 500 amps for the DCX500? If I am correct that 178 amps maximum is quite low, what can be causing this and are there other checks I can make? Could it be that the Field Map #55 is not appropriate for this motor? Provided by EVdrives.com where the motor came from). |
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08-20-2016, 07:49 PM | #2 |
Getting Wild
Join Date: Mar 2016
Location: Lahaina, HI
Posts: 75
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Re: PDS Cart Poor Torque, New Motor
I will add that I measured the voltage right at the motor terminals and is about 46 volts under heavy load.
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08-20-2016, 08:22 PM | #3 |
Gone Wild
Join Date: Feb 2011
Location: Chattanooga TN
Posts: 2,105
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Re: PDS Cart Poor Torque, New Motor
If you want speed you need to get a speed motor. 12 Hp @ 1300rpm's isn't going to get it. You need something like 12HP@ 5000rpm's if you want any speed. It's sort of like the red line thing in a gas engine. In this case one red line is at 1300rpm an the other would be at 5000rpm's
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08-20-2016, 08:29 PM | #4 |
Not Yet Wild
Join Date: Aug 2013
Location: Brunswick, OHIO
Posts: 74
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Re: PDS Cart Poor Torque, New Motor
I am interested in this too. If the motor is calling for amps....why won't the controller supply them? It seems to me that if the cart is slowing down, then the motor RPM must be decteasing too. But pedal position hasn't changed...Still full throttle.
I would think that the electric motor would demand more amps to keep the motor rpm's up. |
08-20-2016, 08:32 PM | #5 |
Not Yet Wild
Join Date: Aug 2013
Location: Brunswick, OHIO
Posts: 74
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Re: PDS Cart Poor Torque, New Motor
If the 12hp 1300rpm motor will move the cart on level ground say at 12mph then why would the rpm decrease (8mph) going up a hill when more amperage is available via the upgraded controller?
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08-20-2016, 08:59 PM | #6 |
Over This Interview Is...
Join Date: Jun 2012
Location: AZ
Posts: 17,449
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Re: PDS Cart Poor Torque, New Motor
what you guys are failing to consider is that any motor at a speed above a couple hundred rpm can not take the controllers full amp output. also, controllers dont "push" amps into the motor, they only allow the motor access to whatever amps it can use for its current load, up to the max limit of controller output. the only time you will see motor amps that are equal to the controllers max output is during the first few feet when doing a quick full throttle launch from a complete stop. a motor cruising at full speed usually has a amp load around 85a.
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08-20-2016, 09:06 PM | #7 |
Gone Wild
Join Date: Feb 2011
Location: Chattanooga TN
Posts: 2,105
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Re: PDS Cart Poor Torque, New Motor
Because it needs more power to climb a hill. If you are using max HP to go 12mph and you hit that hill it needs more power to maintain that speed. And since you are already at max power you slow down. The controller will output more current but since you are at max hp power the motor will convert it to heat.
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08-20-2016, 09:38 PM | #8 |
Not Yet Wild
Join Date: Aug 2013
Location: Brunswick, OHIO
Posts: 74
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Re: PDS Cart Poor Torque, New Motor
But isn't the motor horsepower rating based on amps and volts? More amps should produce more hp. Like more fuel to an engine?
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08-20-2016, 09:44 PM | #9 |
Not Yet Wild
Join Date: Aug 2013
Location: Brunswick, OHIO
Posts: 74
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Re: PDS Cart Poor Torque, New Motor
If a motor only pulls full amps at start up...think, why is that the case? Because it needs it to meet the need that the motor is demanding. The hill is a motor demand too. Then why not pull full amps? The motor on my table saw will trip the breaker if it meets a crisis at full speed. So obviously the amp draw (breaker trip) shows a major motor amp draw to meet the crisis need at full speed.
Not beine argumentative, just still confused how it all works. |
08-20-2016, 09:45 PM | #10 |
Gone Wild
Join Date: Feb 2011
Location: Chattanooga TN
Posts: 2,105
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Re: PDS Cart Poor Torque, New Motor
The line of thinking here is amps produce torque/acceleration. Volts determine HP. Volts are fixed at 48. So HP is fixed at manufacturers rating.
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