42 Volt Limited Top Speed

[SWFLrunner]

Thanks for taking a look. I can only run monitoring test with the wheels off the ground right now due to a personal computer battery issue. I need to get my IT people to install the Alltrax program on my work lap top to get a running on the ground log, they have me restricted from loading currently.


I ran the tests again with today the same results as previously written.

I logged to file but my computer doesn't see the log files in my file system, they're there when I look using the Alltrax program, maybe something with
the file extension so I am unable to send them but the info from post 5 stands.

The field map is EZPDS-DCS-V1, this is how the controller came to me, I have not changed it.

Magnet is 8 pole
set to Turbo and street


This is from post 5 below, notice the oddity in the Alltrax speed limitations and again this test today.

I set it at 8000 max speed limit today and I hit 25 on stock tires another 1 MPH increase. So with the speed limit off I only get to 22 MPH, with the speed limit set to 8000 RPM I get to 25.

From post 5-

<<<<Scotty,

Monitored the cart with the rear wheels off the ground.

Batt volts 44.1 full pedal
Motor volts the same
Field Current 2.7 amps
Battery current bounced between 13.9 and 17 amps
Motor current bounced between 14.7 and 15.8 amps
Controller temp 35.3 C

Thought this was strange:
I set the speed limiter at 6500 RPMs and the motor spun up to 6182 to 6194, bounced between these to RPMs

I reset the speed limiter to 7000 RPM'sand the motor spun up to 6619 to 6633.

The controller came set to 6000 max and I have been running recently with the speed limit off.>>>>

[scottyb]

The max recommended rpm for the stock motor is 6000 because they tend to come apart when spun a whole lot more than that.

25mph on stock 18" tires is 5808 rpms assuming stock gearing 12.44:1

You may have lower gearing?

[SWFLrunner]

Maybe but I doubt it.

This was a golf course fleet cart from 2009 to 2013, all stock. At that time it went into private hands, senior citizen owned until now tooling around the mobile home park. They didn't modify anything from stock, I know them.

Why would the speed be limited with the speed limit off, but continue to climb as I increase the controller speed limit? I can feel the torque increase also when I change it.

[JohnnieB]

Originally Posted by SWFLrunner

1. I logged to file but my computer doesn't see the log files in my file system, they're there when I look using the Alltrax program, maybe something with
the file extension so I am unable to send them but the info from post 5 stands.

2. The field map is EZPDS-DCS-V1, this is how the controller came to me, I have not changed it.

Magnet is 8 pole
set to Turbo and street


3. This is from post 5 below, notice the oddity in the Alltrax speed limitations and again this test today.

4. I set it at 8000 max speed limit today and I hit 25 on stock tires another 1 MPH increase. So with the speed limit off I only get to 22 MPH, with the speed limit set to 8000 RPM I get to 25.

1. Create a new folder someplace that is easy to browse to and browse to it in Toolkit when you tell it where to store the data log. Note: You have to "stop" recording the data log before closing Toolkit, or the file isn't saved. The file extension is .csv

2. You have a PDS drive and the field map is for a DCS drive system. A DCS drive doesn't even have a speed sensor, so I'm surprised it has any RPM data.

This may be what is holding your cart back.

Call Alltrax or the vendor you got the XCT from and ask them to send you a field map for a PDS.

3. The Duty Cycle of the PWM output from the controller is likely to be progressively attenuated as the RPM reaches the limit set rather than a sharp cutoff point. Since only the mass of the rear tires is being propelled, it probably is a bit confused.

It probably will behave better when the cart is on the ground.

4. Both the field mapping and regen braking are mitigated by motor RPM, so for optimal performance turn the speed limiting on.

[scottyb]

The new XCT field map is EZPDS-DCS-V1 is a unimap for both drive systems.
There is a newer version deemed EZPDS-DCS-V1S-V3 which looks like it has a weaker field for a little more speed. I have not tried it but, if you are on the flats with stock tires it may be what you want.

[JohnnieB]

Originally Posted by SWFLrunner

Maybe but I doubt it.

This was a golf course fleet cart from 2009 to 2013, all stock. At that time it went into private hands, senior citizen owned until now tooling around the mobile home park. They didn't modify anything from stock, I know them.

Why would the speed be limited with the speed limit off, but continue to climb as I increase the controller speed limit? I can feel the torque increase also when I change it.

With the rear tires off the ground, only the drag of the bearings and gears are holding the RPMs down, so the motor will spin at a much higher RPM than it can reach when the tires are is on the ground.

I exploded a stock PDS motor running at 42V through a DCX controller, which didn't have RPM limiting. The motor took out the controller also. Very expen$ive lesson.

[JohnnieB]

Originally Posted by scottyb

The new XCT field map is EZPDS-DCS-V1 is a unimap for both drive systems.
There is a newer version deemed EZPDS-DCS-V1S-V3 which looks like it has a weaker field for a little more speed. I have not tried it but, if you are on the flats with stock tires it may be what you want.

My apologies. I'm not up to speed on the later field map versions. Just saw DCS in the name and red flags started waving in the few working brain cells I have left.

I didn't even see the EZPDS prefix.

[SWFLrunner]

I have gained a MPH for every increase in RPM I have set more or less.

It Looks like the program provides a 400 RPM safety factor between the set speed limit and the actual allowed speed limit, the manual touches on this factor slightly.

Now theoretically I am turning the motor at 5800 rpms @ 25mph - this I believe. I do not believe I'm turning the motor at 7600 RPM on the ground because I set the limit @ 8,000. Yet increasing the controller speed limit has increased the speed progressively. Obviously something is off in the software here.

I'm tempted to bump the limit up higher to see if speed continues to increase but I'm getting up against a safety factor at theoretical 5800 RPM now.

I obviously have to get an over ground speed log to verify the running RPM vs speed to verify where I'm at and how far I'm willing to go.

[agpfl]

Is it possible there is an issue with the speed sensor? I know you can install a replacement magnet that tricks the controller into thinking the motor is spinning half as fast as it really is, but maybe you have the reverse problem.

[JohnnieB]

I'm not sure how setting the RPM limit higher will effect the cart's top speed on level ground, but you don't have to record a data log from the XCT to find out if you have some way of accurately measuring the cart's speed. (GPS for example.)

If your tires are exactly 18" tall, the motor will spin 232.31 RPM per MPH.

If the cart goes faster over the same stretch of level road with the RPM limit set higher, than the RPM setting does have an effect on max speed.

The top speed on level ground for a mint condition 36V PDS cart with a stock motor, XCT controller and 42V battery pack on 18" tall tires is about 28MPH or about 6500RPM.