XCT 500 programing

[Helirich]

So I've been playing with the programing. Actually, my computer friend is. We ended up making the throttle leneier setting very shallow for 70 % of the screen. Then it steeply goes up to max. We set the torque curve very steep right away and it hits max about 50 % of the screen.

This gave me a pretty easy takeoff and lots of speed when I want it. It also would climb a very steep hill at a commanded slow speed. (Or fast)

The only issue was reverse. We had the reverse speed limit set at 20%. The top speed was fine, but it would hardly move at half throttle. If you were backing up a hill, it wouldn't move at all until slightly over half throttle and then it was very jumpy. We changed the speed limit to 30% and it seem to be better takeoff. But 30% gave it a top speed of about 12mph. (Alittle fast for reverse)

It appears that what ever you set the forward curves at is what you get in reverse.

Question, I have yet to make and install my 2 Guage cables. I'm thinking they shouldn't effect anything except full pedal proformance. Would I be correct?

[JohnnieB]

Throttle linearity, Torque and Speed curves are interactive and apply to both Forward and Reverse.

I'm not sure what the Max speed in Reverse setting actually does. IE: Limits motor RPM or modifies throttle input inside the controller.

Attached is the Throttle linearity curve I use. Speed and Torque curves are factory defaults, but I'll be experimenting more this summer.

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Actually, the cable gauge and quality impacts all performance at all pedal amounts, it is just more noticeable at full throttle.

[scottyb]

Add more points and smooth those curves out. I can feel the points in Johnnie's curve from the driver's seat

[scottyb]

My wife likes the cart to drive like a Cinderella's pumpkin carriage. So I have to soften it quite a bit when she's taking it for a horseshow where she routinely lends it to everybody.

Here is what I have done to soften it. I think it may help here, as I have 42v and 8 hp D&D motor with just 20" tires on this PDS cart. My apologies for the celphone pictures. See attached

[Helirich]

Well today I borrowed a Windows computer and changed the "field map" to the correct one for my motor. I think all the other settings stayed the same.

Then I took it for a short ride. I couldn't tell any difference. Should I expect to? Tomorrow I will do a speed test.

[JohnnieB]

When I went from the stock PDS motor field map to the motor specific ES7651 field map I gained about 2MPH on the top end. (With 17" tires, would be more with taller tires.)

I couldn't detect any change in torque because I already had more low end torque than I can couple to the road effectively, but in the data logs I see an increase of about 30A in the max amps drawn from the battery over the same test route and more amps means more torque, so there was an increase.

Mathematically, that is a 7.2% increase in speed (aka high end torque) and a 8.7% increase in low end torque.

[Helirich]

I don't think I could tell 2 mph, so it will be interesting tomarrow. I will do the test just as I did it last time. Then I'm going to pump up the tires and run it on the road to see if increases. I can't really run it on paved road because it's far away, but the dirt road is smoother than my yard.

If I drove the cart a couple miles to the paved road. Would you expect much top speed loss due to the battery's going down? I mean, how much will it go down in two miles?

[Clemsoncartguy]

Seeing as carts claim 15to20 mile range (based on batteries) 2 miles is greater than 10% of that range uses. I don't know my electrical stuff like these other guys. But of discharge is linear, my simple brain would say that you will be slower. Would uou be 10% slower...I don't think so? But I have no idea.

[JohnnieB]

Originally Posted by Clemsoncartguy

Seeing as carts claim 15to20 mile range (based on batteries) 2 miles is greater than 10% of that range uses. I don't know my electrical stuff like these other guys. But of discharge is linear, my simple brain would say that you will be slower. Would uou be 10% slower...I don't think so? But I have no idea.

Max motor RPM (Top speed) vs voltage applied is fairly linear and battery pack voltage vs depth of discharge is fairly linear, but linear just means a relatively straight line rather than a decidedly curved one.

A 10% decrease in voltage will decrease the max motor RPM by about 10%, but using 10% of the energy stored (AH) in the battery pack only decreases the pack voltage by about 1%

Also, range is based on only discharging the battery pack to 50% SoC, so if the cart's range was 20 miles and it was driven 2 miles, the battery pack's at-rest voltage would be roughly 0.5% lower at the end of the 2 miles, so the cart's top speed would be slower, but not very much.

[JohnnieB]

Originally Posted by Helirich

I don't think I could tell 2 mph, so it will be interesting tomarrow. I will do the test just as I did it last time. Then I'm going to pump up the tires and run it on the road to see if increases. I can't really run it on paved road because it's far away, but the dirt road is smoother than my yard.

If I drove the cart a couple miles to the paved road. Would you expect much top speed loss due to the battery's going down? I mean, how much will it go down in two miles?

As explained above, the voltage drop caused by the energy used to travel a few miles won't effect the top speed much, however for your cart to reach its top speed, you have to be in a Bonneville Salt Flats mode rather than a drag-strip mode.

When amps are drawn from a battery pack, the pack voltage drops rapidly, but recovers slowly. If you accelerate hard for a standstill, you are likely to run out of level road long before the pack voltage fully recovers from the voltage drop caused by the high amp flow during acceleration.

Let the batteries rest about half an hour after the off-road trip to the paved road and accelerate slowly to about half speed before using full throttle.