New XCT controller adjusting alltrax toolkit

[scottyb]

You did that correctly So many carts, I forget - is the complaint low top speed? Look at the battery voltage when the throttle is 100%. It is alarmingly low. All performance issues point toward the battery pack.
The good news is the battery and motor read the same voltage at full throttle showing the controller is working fine.

[georgia088]

Originally Posted by scottyb

You did that correctly So many carts, I forget - is the complaint low top speed? Look at the battery voltage when the throttle is 100%. It is alarmingly low. All performance issues point toward the battery pack.
The good news is the battery and motor read the same voltage at full throttle showing the controller is working fine.

Well not so much a complaint about speed, but I am trying to figure out why theoretically it should be going upwards of 35 mph on flat ground and its not.

What should the voltage be at 100% throttle? My batteries are 4 year old trojans. Also, in the speed column of the tool kit, is that RPMS?

Thanks!

[JohnnieB]

Originally Posted by georgia088

I think I have attached the file correctly.... I was in a rush (doing this on my lunch break ), and I forgot to even feel of the solenoid after this run. Could the solenoid being very very hot yesterday have something to do with the charging process? I don't think it should but just wondering if it could. I have a dpi 48v charger....

P.S. I guess I should note that I did connect the speed sensor and enable it in the tool kit for this run. Also, according to my gps I was running around 28 maybe slightly higher mph with a fully charged battery.

The solenoid shouldn't be energized while the batteries are being charged and from what I could see on the data log, the solenoid is de-energizing when the pedal is up and the cart isn't moving, so battery charging most likely isn't the source of the excessive solenoid heat.

Is there a label on the solenoid that says what the coil voltage is?

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Try clearing the throttle auto-cal and that may cure having up to 7% throttle when the pedal is up. See attached image.

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The battery voltage as measured at the controller's B+ terminal dropped a bit over 5.5V per 100A of current flow. The voltage dropped to 34.5V while 307.6A were being drawn from the battery, which is significantly high voltage drop, but it recovered quickly so there may some excessive resistance in a cable, connection or contacts. Something getting hot is what to look for.

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The motor reached a max of 5748RPM, which is 30.2MPH is the tires are truly 22" tall. However, if the GPS said 28.0MPH, that means the tires are 20.4" tall.

Guess it is time to break out a level and yardstick to get actual tire height.

[JohnnieB]

Originally Posted by georgia088

1. Well not so much a complaint about speed, but I am trying to figure out why theoretically it should be going upwards of 35 mph on flat ground and its not.

2. What should the voltage be at 100% throttle? My batteries are 4 year old trojans.

3. Also, in the speed column of the tool kit, is that RPMS?

Thanks!

1. Theoretical speed calculations are based on a cart with zero wind resistance, tires with zero rolling resistance, friction free bearings, a perfect amp delivery system and battery pack whose voltage does not decrease when amps are drawn from it. All we can to is strive for perfection and identify where improvements can be made.

As Scottie point out, top speed is determined by the voltage applied at the time. When your cart's motor achieved its highest RPM, the voltage at the controller's B+ terminal was 45.5V, which is about 5V less than the voltage at the beginning of the data log. If your battery pack's voltage had stayed higher,, the cart would have gone faster.

2. At 100% throttle, the motor voltage and battery voltage columns will be the same number. That number will be whatever the battery pack has dropped to under load.

It depends of the climate and many other factors, but 4 years is a better than average cradle to grave lifespan for cart batteries. My cart was coming off a 3 year lease at a golf course in Arizona when I got it and its second set of T-105 batteries were 18 months old and would only take a 88% charge. The batteries now in it will 8 years old in November, but I take care of my batteries a bit better than golf course cart maintenance do.

3.Yes, the is the RPM column. I add a column that I label MPH and divide the motor RPM by a number derived from the differential gear ratio and tire height. That number is 190.069 for 22" tires and it is 245.401 for my 17" tall tires.

Give me the actual height of your rear tires and I get you the number to divide the RPM by to get MPH on the data logs for your cart.

[georgia088]

Ok. So, you think that the resistance of something possibly cables isn't allowing the cart to turn more than the 5700ish RPMS or the age of the battery bank or both? 6500 RPMs is about where you felt the max should be set for my setup if I want to push the limits, should I be able to accomplish this on flat ground?

When I made that run I still had the max RPM set at 6000.

[georgia088]

Also, I should clarify. During that run my max speed was 29.6 mph according to gps. However there is an area that is slightly down hill. So this is when I was running the 5700ish rpms I’m sure. I just approximated the 28 mph based on running both ways.

[JohnnieB]

Originally Posted by georgia088

Ok. So, you think that the resistance of something possibly cables isn't allowing the cart to turn more than the 5700ish RPMS or the age of the battery bank or both? 6500 RPMs is about where you felt the max should be set for my setup if I want to push the limits, should I be able to accomplish this on flat ground?

When I made that run I still had the max RPM set at 6000.

In and of themselves, the batteries in a 48V battery pack consisting of six 8V-170AH batteries drop about 1.5V/100A. There are no perfect conductors, so the inherent resistance in the cables, connections and contacts will add another 1.0V/100A, or thereabouts. So, a healthy set of batteries with a healthy set of cables and a solenoid with healthy contacts will about 2.5V/100A. That means, with a fully charged battery pack (50.9V forTrojan batteries) the controller would see 43.4V between its B- and B+ terminals when it was passing 300A to the motor armature. Your data log shows 34.5V when 307.6A were being drawn. That is about 9V lower than optimal and that means the top speed is roughly 17.5% slower than is likely for your setup.

However, 5748RPM plus 17.5% is 6753RPM, which is too fast to routinely spin a stock PDS motor. AT 6500RPM the your cart speed will be about 33.4MPH. That assuming a tire height of 21.5", which in turn is based on reaching a top speed of 29.6MPH.

The 4 year old batteries very likely need to be replaced and if the cart still has the OEM cables, they need to be replaced also. All ten of them with 4Ga or thicker. For maximum performance, use 2Ga.

Originally Posted by georgia088

Also, I should clarify. During that run my max
speed was 29.6 mph according to gps. However there is an area that is slightly down hill. So this is when I was running the 5700ish rpms I’m sure. I just approximated the 28 mph based on running both ways.

Adjusting tire height to make 5748RPM equal 29.6MPH, I get a tire height of 21.5", so the RPM to MPH factor is 194.489.

[georgia088]

My solenoid is a 48v it is brand new. I got it from Scotty with the new xct controller. I have 2 awg wires everywhere except I think the mains going to the motor. I think they are 4 awg. I assume this is my weakest link.. they are also they longest. I may should replace them.

Edit: actually I lied. I just looked. The short wire going from controller to the solenoid is smaller than 4 awg. Probably the stock one. This is more than likely the weak link. I have an extra 2 awg wire. But it is longer I wonder if I doubled it with the current one. What that would do.

[JohnnieB]

Which solenoid did you get, MZJ400, SW180 or SW200?

All ten cables that carry high amps ought to be the same gauge, 4 Ga or thicker. Since you have 2Ga for seven of the ten, the other three need to be upgraded to 2Ga also.

Doubling up on the short cable from solenoid to XCT's B+ terminal will help considerably.

Also, the short cable from the solenoid and the long cable to the motor's A2 stud should both be landed on the XCT's B+ terminal.
If you land the A2 cable on the solenoid's controller side large terminal you increase the amp flow through the short cable. (The short cable would be in both the Motor amps and the Battery amps current loops. Motor amps often exceed Battery amps when throttle is less than 100%)

The thinner gauge short cable may be the heat source that is heat up the solenoid, and is very likely part to the large voltage drop.

The two thinner cables going to the motor may also be causing reduced performance, but their collective voltage drop doesn't show up on the data log.

[georgia088]

I am not 100% sure about which solenoid, but I think it is the. I chose the controller + Solenoid option (second one down from cartsunlimited).

Also, I connected it like the original diagram shows (both cables connected to xct b+) I assume you are talking about connecting them like the diagram I have modified in red? Are you saying this is right or is not?