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Electric EZGO Electric EZ GO Marathon, Medalist, TXT and RXV. |
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05-31-2020, 06:22 PM | #1 |
48/400/Alltrax HS motor
Join Date: Jan 2007
Location: Liberty SC, Garden City SC
Posts: 6,190
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I learned something today...
I'm not afraid to tell you either.
I have worked on carts for nearly 30 years now and I learned something today that will help me in the future. On a series cart you can put your volt meter on the A2 & S1 and see how much voltage the motor is getting at wide open throttle are at any speed. This can tell you if something is wrong. Bad connections, cables, throttle out put whatever it is. It should be very close to pack voltage if you have enough time to get it up to full speed like I was wanting to do. I want max speed out of little RED so that was what I was looking for. It wasn't getting but 27 volts before Vic & I got on the phone together. I did some looking and testing and found the problem, I have the old pot box throttle it wasn't going all the way to full throttle when I pushed the pedal. I had made a cable pull for it and it wasn't tight enough to get full pedal. It is now. Vic Dejohn @ D&D motor got me going faster now. Top speed was 28/30MPH before I ran out of flat road. Still think it has more though. Went from 18 MPH to 28-30! I'm going to play with it some more next week @ the beach to see if there is any more in it. Vic thinks there is, and I do to. |
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05-31-2020, 06:38 PM | #2 | |
Getting Wild
Join Date: Apr 2020
Posts: 91
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Re: I learned something today...
Quote:
Your cart is bad ***! Love what you did. You have skills. Sent from my SM-G988U using Tapatalk |
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05-31-2020, 07:44 PM | #3 | |
Techno-Nerd
Join Date: Jun 2011
Location: West Virginia
Posts: 19,654
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Re: I learned something today...
Quote:
If you measure between M- and B+ at the controller, you'll get the controller's output voltage no matter how the motor and F/R switch are wired. -------------- If Vic thinks there is more to be had, there must be. What is the differential gear ratio and measured tire height? |
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05-31-2020, 07:50 PM | #4 |
48/400/Alltrax HS motor
Join Date: Jan 2007
Location: Liberty SC, Garden City SC
Posts: 6,190
|
Re: I learned something today...
Thanks, a lot of people may have know this but it was new to me and I will put this to good use in the future.
I sold the Woodie to my cousin last Aug and have regretted it ever since. I had been looking for a new project and found this one in Lancaster SC about 3 hrs away from me so I went and got it. I have a older Ezgo frame out back that has no body on it and want to make a roaster out of it. Like in the first picture. Something a little more adult friendly. The other two are of a friends cart he built at the beach and now Robby Steen of Plum Quick owns it. |
05-31-2020, 08:00 PM | #5 |
Techno-Nerd
Join Date: Jun 2011
Location: West Virginia
Posts: 19,654
|
Re: I learned something today...
Another one that helps when troubleshooting is from B- to M-. Ought to have full pack voltage when pedal is pushed just far enough to make solenoid click and decreases to zero volts when pedal is on floor.
MOSFETs are located between B- and M-, so they are the only open in the high current circuit when the throttle input is 0%. Makes finding an undesired open easy. Going from M- to B+ is good for checking if controller is going all the way up to 100% duty cycle, but not so good for finding a bad cable, connection or contact. ---------- Love the carts. |
05-31-2020, 08:48 PM | #6 |
48/400/Alltrax HS motor
Join Date: Jan 2007
Location: Liberty SC, Garden City SC
Posts: 6,190
|
Re: I learned something today...
Johnnie B is all good info. Vic said to put them on the motor to make sure the motor is getting what the controller is suppose to be giving it when asked for it. That is why I wanted to post this about the motor. If the motor isn't getting what the controller is putting out then the cables are either bad are the connections are. You should see signs of heat at the connections and melting. He also said to keep the temp below 180* C on this motor. What I ran it today it never got over 50*c. That was climbing the hill at the end of the street also several times.
I saw it wasn't getting the correct voltage at wide open throttle so it had to be in the throttle area of it. |
06-01-2020, 12:22 PM | #7 |
Techno-Nerd
Join Date: Jun 2011
Location: West Virginia
Posts: 19,654
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Re: I learned something today...
I agree, connecting to the motor studs is the way to find out if the volts are getting to the motor, but in most carts it is easier to access the controller than it is the motor and if the test I mentioned don't find or point towards the problem, it is time to crawl under cart or remove the rear seat to access the motor studs and figure out which ones to measure between.
The 180°C max Vic mentioned is the insulation on the wires used in the windings and unless you have some way of measuring the stator and armature temperature directly, it needs to be de-rated some. Also, due to the thermal mass of the motor, the case temperature lags the winding temperature by several minutes. The allowable rise is 125°C and I knock off another 20°C for the propagation delay. So what I use is the motor's case temperature before the cart has been moved and add 105°C to it for the max. However, it looks like your motor runs fairly cool. I have to be more careful since I have a sepex motor. |
06-01-2020, 04:00 PM | #8 | |
48/400/Alltrax HS motor
Join Date: Jan 2007
Location: Liberty SC, Garden City SC
Posts: 6,190
|
Re: I learned something today...
Quote:
The heat on our PDS cart at the beach was the main reason I went with the AC swap. I have a habit of riding 6-8 miles at 35 MPH in it at a time and the old DC system didn't like it one bit. The AC system doesn't even get warm doing it. |
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06-01-2020, 07:15 PM | #9 |
Techno-Nerd
Join Date: Jun 2011
Location: West Virginia
Posts: 19,654
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Re: I learned something today...
Motor efficiency determines heat generated and AC motors are more efficient than DC motor and the efficiency of sepex motors drops off quite a bit at both ends of the RPM spectrum. If I run wide open for a couple of miles or creep around my property very long, you can boil water on my motor.
If I was several years younger, I'd probably go to an AC drive and Lithium battery pack, but chances are I'll be sticking with a 42V FLA pack and a sepex motor. |
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