EZGO TXT Super Cart project

[Tsteak]

Originally Posted by JohnnieB

Watch out when reading motor temperature specs and recommendations. In pother words pay attention to the temperature scale used (°F or °C) and exactly where the temperature reading is taken.

The traction motors used in carts usually have a Class H rating, which means the insulation on the wires in the windings are rated for 180°C (356°F).

That number consists of a 40°C (104°F) ambient temperature, a 125°C (257°F) temperature rise and a 15°C (59°F) hot spot margin (fudge-factor).

Unless whoever built the motor embedded temperature sensors within the windings, we are limited to indirect measurements, such as the motor's case temperature, so the values have to be prorated.

From what I've been able to find, max case temperature is 115°C (239°F), so a 180°F alarm setting on your Ex-Ray is fairly conservative. But, remember the motor has a huge thermal mass and the case temperature will continue to rise for several minutes after a hard run.

Excellent info and advice, thank you!!!

With all the covid issues happening, my course closed the cart-barn but has kept the course open for walkers and personal carts I (thank god, 'cause there's virtually nothing else to do...) I loaded mine up in the truck and am using and storing it at the clubhouse (no lithium yet, so no drives to and from home). The most I've played/driven in one shot is about 32 holes and gave a buddy a lift home, by the time I got to the charger, my motor case was slightly over 190*F; it's good to know that's a good benchmark. In a single round, I' seem to get to 130*-140* max. Also, still haven't put in the turf mode, which I think I will limit to 20mph, rather than 25; there is no reason to go faster on the course (although I was quite often at first because it's a new toy and I'm having fun)...

[Tsteak]

HIGH SPEED GEARS.

They've arrived, and I'd like to get them installed today or tomorrow. Anyone done this themselves and have any tips before I go into surgery???

I've not been able to find anything on this... My biggest question is what weight gear oil should I use?

[JohnnieB]

Originally Posted by Tsteak

HIGH SPEED GEARS.

They've arrived, and I'd like to get them installed today or tomorrow. Anyone done this themselves and have any tips before I go into surgery???

I've not been able to find anything on this... My biggest question is what weight gear oil should I use?

SAE 75W-90 full synthetic.

I'm using regular 85W-140 at the moment, but will go to synthetic 75W-90 next time I change it.

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TerryH did a great post when he put 8:1 gears in his PDS cart. Do a search for it.

[Tsteak]

Originally Posted by JohnnieB

SAE 75W-90 full synthetic.

I'm using regular 85W-140 at the moment, but will go to synthetic 75W-90 next time I change it.

-------------
TerryH did a great post when he put 8:1 gears in his PDS cart. Do a search for it.

Thank you!

[Riso]

Here is thread by TerryH on how to change gears. I use 30w synthetic motor oil.

http://www.buggiesgonewild.com/showt...t=57728&page=3

[Tsteak]

Thanks Guys, very helpful. Haven't started the surgery yet, but soon...

Here's a pic of what we're working on, if anyone's interested. In hind-sight, I might have gone with a maple-look dash; I think it might have looked a little better against the black cart, but I'm not at all unhappy:

[bronsonj]

Originally Posted by Tsteak

I'm also thinking of ways to add a cooling fan, and open for suggestions on that!

I pull a Christmas float every year in the parade. That's a load on the cart at a slow speed, both are hard on the motor. I'm running 48V so I put four 12v fans in series on a bar about 9 inches above the motor blowing down. Made a huge difference! I have it set up to turn on when I plug in the fuse, so I only use it as needed but it worked quite well.

Cool cart, btw

[Tsteak]

Originally Posted by bronsonj

I pull a Christmas float every year in the parade. That's a load on the cart at a slow speed, both are hard on the motor. I'm running 48V so I put four 12v fans in series on a bar about 9 inches above the motor blowing down. Made a huge difference! I have it set up to turn on when I plug in the fuse, so I only use it as needed but it worked quite well.

Cool cart, btw

Thanks! I'll experiment with that once I get my battery situation sorted, which is a perfect segue into my next question; I'm considering building a lithium pack, vs. purchasing one. -I fell down that rabbit hole on here last night, and found that building one might save a lot of money...

The pack I would purchase is the 140ah from HPEVS, and will cost me (after I sell/trade some stuff/call in a huge favor) a net of about $3300. They build it with 2 sets of 16, 72ah CALB CAM72 cells. It also has the Orion Jr. BMI and a Delta-Q on board charger built in.

I have found these cells, and other similar cells, on Alibaba at a price that would save a lot of money, I think... I also saw the link for the gen1 leaf cells that bronsonj posted, which is intriguing. But all I know about Lithium is enough to make me dangerous...

With my 600a controller running at full capacity to crank the 8:1 gearing and big wheels, what do I need to know about discharge current? Are the Leaf battery's strong enough for my needs? Is there a good build thread out there? -I saw MCJEFE's build thread, and that looks awesome and do-able, but I didn't learn enough about what I'd really be doing there; why he's got each cell indevidually wired to the bmi, etc...

I have a million questions, is there a thread somewhere that explains all this? It looks like a project I would enjoy, if I knew what I was doing.

OR...

Is it worth the $3300 just to purchase the expensive drop in pack and be done with it?


Thanks all for taking the time to help me with my cart project, this community is awesome!

[Tsteak]

Surgery Complete. 8:1 installed!

I was a bit tepid not knowing what I was getting into, but in hindsight I’d say it’s quite easy for someone who’s mechanically inclined. Terry’s thread helped immensely. The one thing I will reiterate is that anyone performing this will need access to a hydraulic press to change the smaller gear on the intermediate gear shaft. I assure you you will not be able to rig anything to separate the gears; I have a mechanical press that was completely useless. (Got a good chuckle at the fact that I gave away a 2ton hydraulic press about 4 months ago cause I hadn’t used it in years!)

I’ve only just finished the install this evening, so I have only had a couple test runs around the neighborhood. From what I can tell, the top speed will be somewhere around 40 on flat ground. I’m able to cruise pretty easily at 35 going up a slight grade, and can maintain over 30 up a pretty descent grade. After Johnny B’s RPM numbers I am a LOT more comfortable.

40 in the dark is scary, but the cart is still surprisingly stable; I think it will be a pretty tame experience at that speed during the day on the road. Also, I notice very little drop in acceleration with the new gears, and I’m still running lead acid: 8v x 6ea; so tons of weight...

One thing I noticed when I plugged in the usb to the Alltrax to play a bit, is how hot everything is under there after driving a very short distance. The motor case was only at 120*, but the 2g cables were not warm, but hot to the touch; not hot enough that I can’t hold one in my hand, but hot nonetheless. Should I be concerned? I also thought I might have noticed the smell of electrical equipment burning. Alltrax software said the controller was at 40*C, or 104*F...

I’m going to read up on the Alltrax software and play a bit with that, any programming insight is greatly appreciated; mine is the SR model for a series setup. Currently it’s set at 600a for both the controller and batteries, which is my guess as to where the heats coming from... I believe I have much to learn!

[JohnnieB]

Motor RPM:

At 40MPH with 8:1 gears and 20.5" tall tires, the motor spins at about 5250RPM.

The max recommended RPM for your motor is probably 6000RPM or 6500RPM, which translates to 45.7MPH or 49.6MPH respectively, so you probably don't want to exceed those speeds going down hill.

Might want to contact motor manufacturer to get actual max RPM for your motor.

Controller temperature:

The monitor page and data log lists two temperatures, M- and B+
The MOSFETs that feed amps to the motor (PWM output) use the M- busbar as a heatsink the M- reading is how hot those devices are getting. The controller shuts off when the M- busbar exceeds 85°C (185°F).

Total amps that flow through the controller enter the B+ busbar, so it may run slightly hotter than the M- busbar. Not sure if the is an over temperature shutdown for this busbar.

Cable temperature:

I advocate no more than a 10°F rise above ambient (air temperature) for the high current cables, but 2Ga cables ought to be sufficient. Of course, it depends on how many amps are flowing and for how long.

The number of amps drawn by the motor is determined by the motor's RPM. The lower the motor's RPM, the more amps it is capable of drawing and with taller than stock tires and a numerically lower than stock gear ratio, your motor is spinning 43.5% slower than a stock drive system. Depending on the whether the carts is traveling at near top speed, low speed, or something in between, at the lower RPM the motor may be drawing 200% to 300% more amps, maybe more.

Record a data log and post it here so we can see how many amps are being drawn. (You'll have to zip the .csv file and attach the .zip file to a post).

Also might be bad connectors on the cables, or bad connections. If you have a IR thermometer (aka non-contact), measure the temperature of the ring terminals and connections vs the central part of cable.