Uneven/intermittent power

[orangeman6]

My son and I took the cart down to the store today (~ 1.5 miles each way) and it felt like the throttle was cutting out at times. It never felt like there was no power at all, but definitely like it was not outputting all input at times. When I first noticed it, I pulled over and checked under the seat. All connections were good on all high current cables and none of them were even warm. The cart sat for about 30 minutes before we made the trip home. On the ride home, the symptoms were worse.

2001 txt series
58v leaf lithium at 58.2v on my scottyb meter when we left.
Alltrax 48500 with fn switch
Super duty contactor
400 jz (??) solenoid
12" rims with low pro tires
2g scottyb cables

Some moderate hills on the route, but nothing major, and same roads we travel all of the time without a problem.

Pack still with plenty of charge.

I did wash the cart the other day but took a blower to it, as I always do, and the cart ran fine immediately after.

When I got home from today's trip, I checked the motor and it felt fairly hot. I don't have a temp sensor, but I could only hold my hand there a few counts before it got uncomfortable. The motor has been in the cart for a long time and spent probably the first 2/3 of its life going 4-6 rounds a week on the course. From what I learned when I first joined here, it was a factory replacement for the higher speed freedom model. The cart did 21-23 with a good 36v pack. I've had it as high as 32 with the lithium. I have been wondering, with how many miles the motor has on it, how well it will hold up with the lithium.

I think I know the things I need to check, I just have to look up the how for some of them again. If I've missed anything, or someone has other suggestions, please let me know. I'm back to the firehouse tomorrow for 2 days, then have a wedding on Sunday, so it'll be Monday before I can really do anything with it, but I wanted to have a good plan in place.

Hook it up to the laptop and run a file. Out of curiosity, I've been wanting to do this anyway. I gotta look up again how to do this. I know johnnieb has posted it many times, so I should be able to find it easily.

Check the its. Should be able to easily find this too.

I feel like I should start with these two things. I'll do the controller file first and see what it says. Or probably more realistically, what johnnieb says it says. Thanks in advance, Johnnie.

Like I said, I already checked all of the big cables and they all look good. I gave a cursory check on the others, and didn't see anything wrong, but I can look a little harder there. I already bypassed the molex when I did the rebuild, so that's out.

Again, if anyone has any input, I'd appreciate it. Also, if it is the motor, I'll take suggestions based on the usage info below.

Thanks

Mostly a pavement queen with the occasional trek down some fire roads
Cart lives in the foothills of Northern California. No major hills
Currently only a 2 seater and most likely staying that way
12" wheels with low pro tires. ~18", no lift

I'm actually getting pretty used to the 30mph+ top end. I don't drive it like that often, but it's nice to have when you want it. However, I don't want to crawl uphill, so torque is a bit of a concern too. I was completely happy with the speed v torque in the current motor. Unfortunately, I can't get any specs on it. The only markings on it are a sticker that says " Santiago golf cart supply". A frequent contributor here, who I haven't seen post in a long time, is the one who told me it was a factory replacement for ezgo' upgraded motor.

Thanks again in advance.

[BobBoyce]

The symptoms sound just like bad contact between the brushes and commutator, causing excessive arcing. It might be time for a new set of brushes and taking some emory cloth to the commutator. Be sure to clean out the commutator slots afterwards.

[orangeman6]

Originally Posted by BobBoyce

The symptoms sound just like bad contact between the brushes and commutator, causing excessive arcing. It might be time for a new set of brushes and taking some emory cloth to the commutator. Be sure to clean out the commutator slots afterwards.

Thanks Bob, I had been thinking for awhile that I probably should do this anyway. I’ll look up how to go about it. Since I don’t have the specs on my motor, am I going to be able to figure out which brushes I need?

[BobBoyce]

Originally Posted by orangeman6

Thanks Bob, I had been thinking for awhile that I probably should do this anyway. I’ll look up how to go about it. Since I don’t have the specs on my motor, am I going to be able to figure out which brushes I need?

You can take the motor apart and take the brush assembly to a motor shop and let them match it.

[JohnnieB]

With 18" tall tires and 12.44:1 (stock) gears, your motor is spinning over 7400RPM at 32MPH.

Unless the commutator is too far gone to repair, it might be an idea to send it to EMP for a rebuild plus high speed banding and balancing. http://empinc.biz/about-us

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Unlike Sepex motors, series motors typically don't have speed sensors or controllers with RPM limiting, so it is possible to spin the armature fast enough to explode, especially going downhill with pedal on floor.

[yurtle]

I used to routinely get my stock tires and gears, and series motor in my sig in excess of 32 mph (haven't done it in a while so I don't remember exactly how fast). I'm not saying "I did it so it must be safe". I may have just been lucky, or my motor may be beefy enough.

Someone way smarter than me would need to answer this, but could regen contribute to the failure? Would a series or regen be worse if you suddenly took your foot off the pedal while going that fast?

I have a little 1 hp 1,760 rpm 3 phase motor that I routinely run at 200 Hz.

[orangeman6]

Thanks to all of you for the replies.

I'll have to consider doing whatever is needed to this motor vs a rebuild from EMP. I like the idea of the high speed banding or whatever else would make it likely to better handle what I'm asking of it. I'll call them on Tuesday, but it seems like it will be somewhat difficult for them to tell me much without the motor in their hands, as I don't have any specs on it???

In the meantime, obviously the motor needed to come out, plus I was curious to see what it looked like inside. I was completely convinced that mine would be stuck on the spline since its been in there so long and it's got a lot of miles on it. Luckily, it came off very easily. A little bit of wiggling, and it was free.

I'm doing some searching now, but does anyone have any thoughts on what they see in the attached pics? I don't know what I'm looking for, but compared to other photos ive seen, the commutator doesn't seem to be in bad shape. I'm not sure how to get the end cap off ( is the bearing holding it on?) so I can get a good look at the brushes, but the look to be evenly setting against the commutator. I was surprised at how dirty it is. I would think it would run poorly just based on how much stuff is covering the parts attached to the case.

Can anyone tell from the photos if they see any problems?
I know I read about emery cloth to clean up the commutator, but what is safe to use to clean the rest of it up, all of the debris/grease? I'd like to get it all cleaned up whether I repair it myself or send it to emp or a local shop.

Thanks

[orangeman6]

Only letting me attach one photo at a time from my iPad.

Alright, it let’s me do multiples from my phone. Let me know if any other pics would be helpful.

[BobBoyce]

Originally Posted by orangeman6

Only letting me attach one photo at a time from my iPad.

Alright, it let’s me do multiples from my phone. Let me know if any other pics would be helpful.

That motor has been extremely hot multiple times. There is galling on the inside of the stator laminations and outside of the rotor laminations. The commutator has interlaced discoloration, which is what indicates repeated overheating. Galling without bearing slop indicates that the armature laminations expanded from overrev of the armature and came in contact with the stator. You've exceeded its design RPM by quite a bit. It's going to need a total rebuild, OR, clean it up, take emory cloth to the commutator until it is bright copper once again. Clean up the stator and rotor laminations with emory cloth to smooth them out, and coat the surfaces with a wiping of SAE motor oil after all cleaning is done to reduce rusting. That will buy you some time, at reduced RPM, until you can rebuild or replace. If you continue to run it as it is, it will fail. Dramatically.

When I was doing motor rewind, a motor like that would not qualify without replacing the armature. The stretch damage to the armature laminations has likely left permanent stress cracks internal to the laminations. There is no safety margin left to allow it to run long term at rated RPM.

All of that black gunk is what is left of the formvar (Motor Varnish) that used to coat the windings and laminations. The only thing that holds the windings firmly in place in a motor. It has cooked and flaked off, being ground into dust and larger particles.

[orangeman6]

Bob, thanks very much for the info.

It doesn’t sound like it’s worth cleaning it up and putting it back in if I’m just going to hurt it again. My question now is: is it even in a condition to send to someone like EMP? If I’m understanding you correctly, it sounds like you’re saying I need a whole new motor unless I’m going to keep the rpm’s way down from where I have been?

If it is worth doing something with, how do I clean all of the “gunk” out of there? Mild detergent like dawn ok?