Customize alltrax controller for best speed

[yurtle]

It would be useful to have the next datalog with only one variable changed. If possible, just change cables, datalog, fill tires, datalog.

Longer cables won't really hurt. but if JohnnyB wants to crunch the numbers, knowing before and after lengths will make a difference.

[JohnnieB]

Originally Posted by Thrillercart

Thanks so much guys. This is great info.
1) my tires are 20 max psi. Looks like I only have 7-10 in them currently. So I’ll be inflating them to 18-20 and that should help speed.
2) I’m getting lengths to get cables made. I used the 6 gage ones in place for the thin ones to the motor. I am replacing the 2, 6 awg wires to motor with new 2 awg.
3) the short 6 awg from controller to selenoid was the one getting hot. I used one of my longer 2 awg from original kit in place of it. It’s like 24” long but really only needs to be 12-14”. Is that a problem? I’m getting 2 shorter 2awg from battery -/+ made because the ones they sent were extra long. So really the only one that has access length is one from controller to selenoid. Should I use a shorter one there and use this 24” from battery - or + instead? Is there a place where access length isn’t as big an issue?
4) once I get cables in and installed, I’ll re monitor the cart on that drive and attach the file.

Thanks!!!!

1. Underinflated tires are definitely part of the poor performance problem. Takes a lot of amps to turn soft tires.

2. Unless the original F1 and F2 cables have worn through insulation (Typically happens where they are routed around battery box), or corrosion on the connectors, they probably don't need to be replaced. Max field amps a XCT will pass to motor is something like 30A and the max seen on your data log was only 17.3A. I'd also question the health of the original 6Ga cables, they've been in an acid rich atmosphere for over 20 years.

If you want to replace the F1/F2 cables, use new cable.

3. If you have the A2 cable to the motor stacked on the controller's B+ terminal along with the short cable from the solenoid's controller side large terminal, the extra foot of 2Ga is only costing you about 16mV/100A of current flow. (6Ga is about 40mV/100A/foot)

If the A2 cable is stacked on the solenoid's controller side large terminal, the short cable will have more than battery amps flowing through it when the duty cycle of the PWM output from the controller is less than 100%.

Best bet is to keep the cables as short as possible, but be aware that that things move around while the cart is in motion. The frame flexes, so the batteries move relative to each other and the battery pack moves relative to the solenoid and controller. Torque flexes the rear springs (tries to make them "S" shaped rather than arches) during acceleration and deceleration, so the motor can move several inches from front to back so the cables to the motor need plenty of slack.

4. FWIW: I have a test route laid out for comparison testing. It is about 10 miles round trip and includes paved roads, city streets, open fields and mild to steep hills.

[Thrillercart]

ok. I finally got my 3 remaining 2awg cables in and installed. So now i have 2 awg for all the batteries, the + and -, the 2 cables going from controller to motor, and the controller to selenoid cable. So i added the 3 more 2awg to have all 10 replaced. Here is the monitor zip file for the test drive with just the 3 added 2 awg cables.... I'll send another monitor file shortly with tires inflated to 10# each...

[Thrillercart]

ok. the tires were at 8 psi. now they are at 15 psi which is good for me. Here is the file after infalting tires after last test above.

looks to me with my GPS, i increased speed with upgrading the other 3 wires by 1.5-2 MPH. and then another 1 MPH with adding 7 lbs of pressure to tires. I'm very happy with it how it is. about 21 mph on flat ground.

The motor and brushes are old they seem, but i will keep it like this for now. in the future, id like a more torque motor for tires and passengers. but let me know if i need to still change out brushes.. ive never done that and dont know how difficult that is.

Thanks for all the help and i hope these files tell us something. let me know

[yurtle]

Kewl.
I won't be playing with it, but realize it's very rare to have step by step performance data. I know I changed nearly everything at once, though in my case, my poor stock controller couldn't datalog.

[scottyb]

I must say you drive it like you stole it
A quick look reveals the pack we started out with a full 38.4v and the motor draw 300 amps at the 94 min marker and consistently hits 100 amps and above at 100% throttle. That's more than you would like to see. It is pulling the fresh pack down to 34-33 volts which is hampering speed and power.
What motor is this?
How old are the batteries?

[Thrillercart]

Ha. It was raining and i was trying to get the test run done... The batteries are 2018. Prob 10 mos old. The motor is old. I would bet it’s the original one as it doesn’t look aftermarket. I can try and get model and info off the motor. Would just replacing the brushes help? I know nothing about motors or how they work. Thanks

[yurtle]

ScottyB's reading of your datalogs indicates an apparent "excess" amount of amps, which is possibly due to excess drag on the cart. I'd put cart up on jack stands and make sure everything rolls +/- freely - no dragging brakes.

I've got a lot of experience with DC brush motors, but little with buggies. My experience is that brushes either work or they don't. As a brush wears, it actually has LESS resistance, but the commutator also gets dirtier so...

I assumed my 1998 motor needed brushes and bearing, so I replaced both. Pretty easy.

[yurtle]

Oh. Answer ScottyB's questions.

[DaveTM]

^^^^^^What he said^^^^^^