New Alltrax TXT48300 install question/issue

[bronsonj]

Thanks for the spreadsheets Johnie B.

As for the math, 4 questions took an hour and we're not sure that all 4 were correct by the end...

One of them was a 2 part question. come up with the equation for a word problem, 26+13=39 was the equation. Part 2 was to simplify the equation and tell which property you used to simplify it...

How much simpler can it get than 26+13? I understand an equation like ((10 + 6) + 10) +50 + 13 - 50 can be simplified but 26 + 13... Oy Vey.

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On to the more important stuff. I have NOT uploaded the field mapping yet. Was gone all weekend. I do have my new BMS so that will be going into the cart this week too. Good times. Updates to follow.

[JohnnieB]

Originally Posted by bronsonj

Thanks for the spreadsheets Johnie B.

As for the math, 4 questions took an hour and we're not sure that all 4 were correct by the end...

One of them was a 2 part question. come up with the equation for a word problem, 26+13=39 was the equation. Part 2 was to simplify the equation and tell which property you used to simplify it...

How much simpler can it get than 26+13? I understand an equation like ((10 + 6) + 10) +50 + 13 - 50 can be simplified but 26 + 13... Oy Vey.

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On to the more important stuff. I have NOT uploaded the field mapping yet. Was gone all weekend. I do have my new BMS so that will be going into the cart this week too. Good times. Updates to follow.

When I was going through an electronics fundamentals course, as homework, the teacher held up a sheet of paper with about fifty resistors connected in series and parallel drawn on it in pencil, with a point labeled A on one edge of the page and point labeled B on the other edge and ask us what is the resistance between points A and B. When asked, he put the sheet in an overhead projector and we all drew the circuit so we could figure it out. Needless to say, we students brought in several different Ohmic values we had figured out and the teacher said they were all wrong and told us to try again the next night. The next day (after some overnight collaboration) we all had the same answer, but we were told it was mathematically correct for the resistance values given as connected, but didn't answer the question asked.

Then the teacher produced and Ohmmeter and measured the Ohmic value of the graphite lines between point A to point B on the paper. To say the least, it was a learning experience I shall never forget.

Years later, when I was teaching troubleshooting in the Air Force, I occasionally plagued my students with a logic diagram that covered four pages and had to be reduced to its simplest form using Boolean Algebra. Its simplest form was a solder dot gate, or straight piece of wire.

Of course things were different back then.

[bronsonj]

I took new logs today, but I guess when I unplugged the USB cable I had not closed the log first? Anyway, the logs are gone. I did see > 5500 rpm while riding with the laptop open. Phone GPS said I hit 31mph (Skinny neighbor and I were on the cart this time). I compared the phone to wifes 2017 Ford Flex and the phone says I'm doing 1 to 2mph less than I really am, assuming the flex is right. So that puts me at 31 or 32 mph on the cart which is pretty cool!

Came back from the corner store on a side road and I was doing the speed limit... I rather like that!

I'll try for logs again tomorrow and see about posting.

[JohnnieB]

Originally Posted by bronsonj

I took new logs today, but I guess when I unplugged the USB cable I had not closed the log first? Anyway, the logs are gone. I did see > 5500 rpm while riding with the laptop open. Phone GPS said I hit 31mph (Skinny neighbor and I were on the cart this time). I compared the phone to wifes 2017 Ford Flex and the phone says I'm doing 1 to 2mph less than I really am, assuming the flex is right. So that puts me at 31 or 32 mph on the cart which is pretty cool!

Came back from the corner store on a side road and I was doing the speed limit... I rather like that!

I'll try for logs again tomorrow and see about posting.

Is that after loading the correct Field Map?

With a clear view of the sky, both GPS receivers and GPS phone apps are more accurate than automotive speedometers, however, this is true only when the vehicle is traveling at a steady speed since GPS speed lags real time when vehicle is accelerating or slowing. Since the only metal between the GPS receiver and the sky is the roof support, your phone has a clear view of most of the sky, so you phone GPS app ought to be the most accurate.

If you really want accurate, measure the rolling circumference of your rear tires, then calculate how many tire revolutions per mile, then factor in the final drive ratio of your cart and then divide the motor RPM by 60 to get MPH. Of course, I've got a spreadsheet that does that when the height is known.

To get a reasonably accurate tire height, place a level on top of tire and use a yardstick to measure the distance the the ground. If you want more accurate, measure how far the cart travels per tire revolution. For greater accuracy, measure distance traveled for several tire revolutions and average.


Here is a list of the numbers to divide motor RPMs by to get MPH for tire heights from 16" to 25" in 1/4" increments.

If you can give me either the tire height using the yardstick and level method or the rolling circumference method, I can give you the exact number to diving the RPM (speed column) of the data log by to get very accurate MPH for your cart.

[bronsonj]

Thanks again Johnie!

Time to actually measure the tire I suppose.

The field map I used was the one ScottyB attached to this thread.

I did go for a ride to my buddies house and did some donuts in his front yard the night before last... I was really doing him a favor as his grass was about 12" long. It was one-wheel-peel type of thing on a hard turning radius with 2 people in the cart, not the tail-wagging type donuts but it's still quite a bit of fun!

[bronsonj]

I did two more logs and both disappeared on me. I checked for hidden files and the like, no dice. Finally I right clicked and selected Run as Administrator on the Alltrax software and did a new log, this time it stayed there.

It is a .csv but I had to rename as .txt because the forum wouldn't let me upload a .csv file.

JohnieB, if you could look at this and just rename it from a .txt to .csv and give me your opinion on it I'd appreciate. This was a fairly long full throttle run on a half charged battery.

5708 rpm max. 73" circumference. 31.74 mph unless I did that wrong.
But, 5708 was only briefly.
The average of the top 20 fastest rpms is 5693 for 31.65 mph. Big difference. But I'll take it...

[bronsonj]

Oh, and thank you for your RPM/Circumference/mph cheat sheet! Saved me from fumbling around in Excel for half an hour!

[JohnnieB]

So your tires are marked 25" and measure 23.25", nearly 2" shorter than marked.

You speed calculations appear to be correct.

The other map was only taking the field down to about 2.4A and this one is taking it down to 1.7A and giving you another 800RPM or so. I corrected the tire size data on the DQRun2 and you were getting 27.2MPH max and now it is 31.7MPH, or about 4.5MPH faster.

What is your Max RPM slider set to? You said 5900 in an earlier post. If so, I'm pretty sure you are bumping into the the speed limit as set in the controller. What I'm seeing is the Field Amps starting to increase from the 1.7A minimum at about 5400 and climbing back up to up to 2.4A above 5600. In other words , the controller appears to be using the field amps to limit max RPM.

The max speed limit isn't a brick wall, the controller starts progressively backing off the motor as the RPM approaches the set point, so the max RPM reached tends to be a bit below the set point and if you want to allow the motor to reach 6000RPM, the set point may need to be a couple hundred RPM higher than 6000.

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Looks like the max amp rate being returned to the battery during regen braking was a little over 65A and the max battery voltage reached during regen braking was 54.4V.