Excel Precedent to fast??? Burnt motor out

SCCLT

First time cart user/owner, 2010 CC Precedent, S/N PD1016-xxxxxx, rear seat, new T-875 batteries, stock components AFAIK, speed code 4 upgrade, 205/50-10 tires, w/regen (see more below). Use cart on 25 mph roads and paved trails inside of development. Terrain is mostly flat with about 20% of it slight/moderate rolling hills.

After reading a lot of the threads here I’m starting to think that my cart is not pure stock. I’ve clocked it using the GPS on my cell phone in the mid 20’s on level terrain and have seen low 30’s on the down hill. It’s not fast out of the gate and it scrubs off considerable speed going up hills, normal, but more than expected. Almost as though high speed rear end ratio (unknown, but will check when I get cart back).

Tahoedawgz71 said that he had found two repaired controllers where the speed monitoring had been removed. My cart still has Regen but not at WOT high speed going down hill. This is the source of my problem I suspect. Also, if going 25 mph and you lift the throttle, “throttle up” the cart has to free coast down to about 20 mph before the regen will kick in slowing the cart to about 10 mph where then Regen then disengages. Now it has to free coast down to about 5 mph where Regen will again engage and slow you to almost a stop. If you push/roll the cart it will beep and resist.

Late Thursday, after about 4 miles of mixed use, following a down hill run and starting to climb the other side the cart died and coasted to a stop. We could smell something burning. Battery bank = 50+ volts. Dealer picked up cart Friday morning and called before noon to say that the motor was toast. He’d warned me about this when I bought the cart. In haste we ordered a replacement motor, a MOT-A2, which didn’t require a useable core exchange.

Now I’m concerned that my controller has been “repaired” such that it no longer protects my motor from my heavy foot. Particularly going downhills.

So of course I have a lot of questions due to my lack of knowledge / experience.

1. What do I need to create a bulletproof cart that will run 22-25 mph WOT and not melt motors when going downhill?

2. Is this motor, MOT-A2, a good fit for my application?

3. I read that WOT is better for cooling the motor that partial throttle. Does this apply to Excel/SEPEX motors or is that just for Series motors/controller?

I’m sure I’ll think of more questions but this is enough for now. Thank you in advance for any advice that you can offer.

Attached Images

Motor.jpg (18.0 KB, 0 views)

BGW

__________________
This advertising will not be shown in this way to registered members.
Register your free account today and become a member on Buggies Gone Wild Golf Cart Forum

55BigBlock

I'm sure others will chime in but I think it was the long downhill run that got you. The increased RPMs from the downhill speed caused the motor to come apart. When I bought my new motor I was told not to let the cart exceed its top speed while going down steep hills. Just my .02

SCCLT

Thanks 55BigBlock, I agree on the high speed downhill run and that makes perfect sense... But the motor didn't "fly apart" or "grenade" like I'd of thought.

See an example of excessive R.P.M. on the Plum Quick Motors website. https://www.plumquick.com/assets/doc...o%20Notice.pdf

If you look at the photo on my original post it's more like the non moving parts (field windings) melted due to excessive heat.
The dealer tried to explain this as, and don't quote me on this but this is what I was hearing, "Going downhill so fast all that extra electricity has got no where to go and gets jumping around and it then just makes a mess of things." Huh???

Looking for someone to tell me that everything is going to be alright and that I'm not going to be spending $$$ every few months on new motors, etc.

I would think that once a preset RPM limit was exceeded that a good/functioning controller would engage regen and slow things down.
Is this possible/available?

I'm hoping that my current controller was modified so as to have defeated that particularly useful function. Then I can just buy a new controller, solenoid, cables, etc. and leave my foot flat on the floor. Anyone?

Sergio

At 6,000 rpm the motor armature is rotating 100 times per second, that creates a tremendous centrifugal force that is trying to repel all of the copper wire form the armature.

The weak point is where the armature windings are soldered to the commutator, and the problem gets worse as the armature heats up and weakens the soldered joints.

Motors designed for high speed have a "banding" tightly wrapped around where the copper from the windings are soldered to the commutator.

That "banding" keeps the copper wire from being repelled at higher rotational speeds.

The picture from your motor is not real good and it is from the wrong end of the motor.

You really need to see the picture form the other side of the motor where the brushes and commutator are located.

Most likely the damaged rotating armature snagged some of the field wires and broke them OFF.

What kind of motor is that?

The stock motor is black, but it is kind of hard to see it on your picture.

If you replace the Controller with an Alltrax Controller, You can set the maximum rpm you want the new motor not to exceed and you should be in good shape.

If You like the motor to spin at 6,000 rpm or 7,000 rpm often, You should invest in an optional high speed "banding" for your motor.

SCCLT

Thank you Sergio, All great information as usual. I've pulled the rotor and end cap out of the black case and took some additional pictures as you suggested. Based on the data tag (Photo #4) motor is a stock black ADC. But it has what looks like the banding that you discussed (Photos #1&2). Perhaps this banding is stock and performance motors have more/better banding? Also top right of photo above data tag shows a date stamp of 05 13 which is three years newer than my cart so it makes me wonder if it is stock or not???

I agree that centrifugal force and heat in the rotor is what trashed the motor. If you look at photo #2 you will see that the copper coils on the gearbox end of the rotor was slung outward and then in photo #3 cut through the field winding on the black case. Surprisingly the brushes and commutator end of the motor looks pretty good, at least from what I can see without getting the rotor pressed out of the end cap. (I'm guessing that's how it's done).

For now the dealer has ordered the Admiral MOT-A2 motor as it didn't break the bank and it didn't require a useable core exchange. It's suppose to be here tomorrow (Wed) fingers crossed.

Good to hear that a properly functioning controller will limit top RPM. I of course assume that this works on level terrain and downhill within certain given physical limits, such as amount of Regen programmed, the grade of the hill, etc.

Based on what I read here on BGW I should be able to use the Alltrax 300 amp unit with the stock cables and solenoid with the MOT-A2 motor. I'm inclined to go bigger now though, either the 400 or 500 amp unit for possible future modifications. You can always dial a bigger unit back, but you can't dial a smaller unit up. Any other benefits in starting with a bigger unit? Cooler operation? Better economy?

Attached Images

	1.jpg (13.7 KB, 0 views)
	2.jpg (16.1 KB, 0 views)
	3.jpg (19.7 KB, 0 views)
	4.jpg (22.0 KB, 0 views)

yawood

What rpm would you recommend that it be set at for a stock motor, Sergio?

TahoeDawgZ71

I vote for the Alltrax. And FYI, the MOT-A2 is not going to play nicely with the Excel controller. It has a high speed magnet in it. The Excel controllers don't work with high speed magnets. I've never tried it, but I see no reason why you can't take the magnet out of your factory motor and install it in the Admiral while you're running the factory Excel controller. That should make it work normally. Once you install the Alltrax, you can leave the OEM magnet in the motor, just make sure you set the pole count to 8 within the Alltrax Software.

Sergio

I think it would be unusual for the controller not to be damaged since there was plenty of contact between the Armature and Field windings inside the Motor.

I also think the Alltrax Controller would be a better choice and 400 amps is a good size for Sepex carts.

There is a speed calculator link under the "Quick Links" on the top right menu bar.

If You use the defaults:

Final Gear Ratio = 12.315
Tire Diameter = 18

You can play with the rpm value to figure out max speed, 6,000 rpm = 26.1mph

I think that should be the limit for stock motors, but if the drive/load conditions keep the motor hot, You may want to lower the limit to 5,500rpm.

SCCLT

Stopped by the shop and the new motor arrived this morning. Hope to get the cart back home today. Asked to owner, after the motor is installed, to please plug in his Curtis programmer and check things out. Also asked him to reinstall "speed monitoring" At first he said that code 4 removed that but then he said that he would check it out.

Looking to upgrade controller, solenoid, & cable set ASAP anyway.

SCCLT

Hi David, agreed that the Alltrax looks like the way to go. I've read so much the past four days, I can't remember who said what, but you, Scottyb & Sergio all have very sound advice. That's not to so say that others don't, it just seems that when someone is really deep in the weeds you three seem to bring the light of clarity to the problem. The dealer called "Red Hawk" to order the motor, while I was standing there, and gave them my cart S/N# and they said this motor would work. Perhaps they swap in a stock magnet before they ship it. Hopefully they do anyway. As I said I'm not 100% sure what I have. I know that my cart would slow down by what I would call medium Regen in certain speed ranges as noted in a previous post. It did not limit top end on level or down hill. Is this indicative on a speed magnet on an Excel cart? So many questions, so many options, so little knowledge on my part.