Motor Burn Up at 32AMAX

Ahoy All , newbe here with a trouble shooting problem . Grin equiped with CA 2.3, Grinfineon 48-25 , 6 ea LiGo's ,,, using sensorless mode .
Riding using throttle only about 12 mph , flat ground , towing a light load in trailer , everything fine with full batt charge ,,,, then upon increasing the throttle , motor sounds rapid Tat tat tat ect and CA indicates 25A over draw, and power to motor shuts down . I stop , put kick stand down tilt bike over on the stand to free rear Bafang hub wheel, to test the throttle . At first (low throttle) the wheel spins fine, but as throttle is increased that Tat-tat-tat starts and motor looses power .

It seems to me that the CA or the controller sensed a load over the 25A max draw and the CA was bouncing on and off rapidly . Sounds like I have a direct short somewhere , but would that problem just start , when everything else was going fine ?

Any ideas on how to trouble shoot a problem like this ?

Are you perhaps hitting your low voltage cutoff?

It sounds like LVC. I have the same controller and that's pretty much exactly how it acts. If it's happening with a full battery check your battery wiring for bad connections.

First connect throttle directly to controller, bypassing the CA, so the CA can't be limiting the system. If the problem continues, it's not the CA causing it. If the problem stops, then something in the CA is limiting, potentially causing the issue; you'd need to review the limit flags screen to see which one is doing it.

Thanks neptronics and dustNbone for your replies .
Also Thanks to amberwolf too ,,,, BTW , I did the tests you recommended , but no joy .

Upon re-reading the Grinfineon Controller Manual , on page 11 , #3 Core Features and 3.1 LED Indicator , a list of controller fault problems shows that by watching the controller red indicator LED you can determine by the number of flashes what problem the controller is having .
My troubled controller has a 2Hz blinking LED when turned on just indicating sensorless mode .

So how do you get the LED to blink the controller state flash signals ???

:? Since by-passing the CA with the throttle only didn't change the problem .

dwkayaks said:

So how do you get the LED to blink the controller state flash signals ???

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You don't. It will automatically flash any error condition it has.

Since it says it's running sensorless, and you want it to be doing that, then it isn't signaling any errors, so there's no condition within the controller that's actually a fault that it can detect.'

Doesnt' mean something isn't wrong with the controller, but I'd start looking at other things. First, connections, both phase and battery. Next, battery itself.

And remember also that any error messages are probably only going to show up during the actual event, and not afterward or before, so if the controller *is* giving an error, you'll only see it then.

Ahoy All , Justin advised to check the geared hub motor as well as the wireing and connections ,,,, Well , the problem I found was 3 burnt coils in the stator , shame on me for using more energy from my motor than it could provide , Ouch !

Ahoy All , newbe here with a Question ,,, What amount of electrical current and for how long , would burn up the stator coils in a eZee 250 RC geared hub motor ? My CA registered 32AMAX before the motor died under load .

BTW what does a motor with burned up stator coils sound like using the throttle only ? or ,,, how to use a multimeter to check for stator coil faults ?

You can use the ebikes.ca motor simulator to get an idea of what

32A is a lot for an ezee, but that depends on the volts. Really.. you want to consider how many watts you were throwing at it, not how many amps.. it is a 1000 watt rated motor.

You can do electrical tests and all, but if it died from heat, it'll be obvious what happened when you open the motor up.

Possibly more like a 500w rated motor, but geared motors can generally take 1000w continuous for a while, like long enough to get moving from a stop, or a mile long hill.

But if you are running 48v, then 54v x 32 amps is 1728 watts. It should take that easily for a standing start, since watts will drop to more like 1000w by the time you reach 20 mph or so. But if you are riding in deep sand, mud, or up a hill and weigh 200 pounds, you will pull more than 1000w for plenty of time, and easily cook off the motor. Your controller could even cook off the motor with less than 1000w, if you load it down enough. In general, up a long steep hill with more than 300 pounds, you the motor and the bike, will risk cooking off a motor. over 300 pounds, 6% grade will do er easily.

If you rotate the motor backwards, and it resists a LOT, you cooked off the stators, the phase wires. If not, you may have only fried the halls. You can check halls with a 4v battery and a multimeter. 4v to the black and red wires. multimeter to a black wire and one of the colored wires. Rotate backwards, and a good hall will turn on and off on the colored wire. As said above, a cooked off motor is pretty obvious when you open it. It will reallllly stink when you get the cover off a burnt motor, and the winding will be really black, not just browned.

Ahoy Dogman Dan , T Y for this reply . Yes, I was towing my Aosom trailer with a load of groceries up a short "motor killer" hill , topping out a 1.5 mile , 200' elevation gain .

This was the second motor I have burned out the stator coils , Ouch ! I guess that now I need to learn coil re-winding , and should feel lucky to have two motors to practice on .

Do you know why eZee doesn't sell replacement stators or is it that I don't know where to look ?

I will also need to learn wheel building as this eZee motor has to be unlaced to open the hub , Ouch !

In that Deep Dive interview with Justin , he says they have a shelf of spoiled and burned out motors at Grin Tech , so I guess this is a re-occurring problem with ebike hub motors .

LOL, Sounds like possibly you may need a bigger motor than the EZ for this job. Or pedal harder...

Oops on my mangled first reply.

Anyway, your motor was not up to the job anyway. You needed something larger. A MAC might have been okay, as it's got, i believe, a larger stator than the eZee. The next move up is to a 30mm or 35mm wide direct drive, which are capable of handling 33-100% more power.

You can use ebike.ca's simulator to put your motor and battery and controller configuration and point it at a hill and find out if it overheats or not. It's a useful tool to decide what motor to use.

Also helps to check for heat by hand on a motor when you're really pushing it. It was probably so hot you couldn't touch it halfway up the hill.

We don't know how much wattage you were running though since you only specified amps. Whatever it was, it was obviously more than the motor could stand. If you fix it, it'll fail in the same condition due to heat.

ebikes.ca has a giant pile of dead motors because someone specced them wrong for the power they wanted. Learn to use the simulator and you will save yourself from further expensive mistakes.

Oh, by the way, you can identify a burned up stator by it's harsh chemical smell..

Often on the MAC/eZee/BMC motors, the hall sensors will die from heat before the stator burns up though.
In that case, it'll usually stutter when you try to spin it up.

If the coils have shorted, it usually won't even fire up. You may have blown the controller from a short.

dwkayaks said:

Do you know why eZee doesn't sell replacement stators or is it that I don't know where to look ?

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Don't know any of them that do normally, though I'm sure you could contact them directly and order just a stator--it'll probably cost more than a whole motor though, just because it's a special order (different from the normal order of whole motors).

Even if someone does sell just the stator, then given the weight/size of stator vs whole motor, it'd probably cost you close to the same in shipping anyway, even if just the stator didn't cost as much.

I will also need to learn wheel building as this eZee motor has to be unlaced to open the hub , Ouch !

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Are you sure? The ones I've seen only have to have the side cover unscrewed, and both spoke flanges are on the same part as the other side cover (with the ring gear on the inside).

In that Deep Dive interview with Justin , he says they have a shelf of spoiled and burned out motors at Grin Tech , so I guess this is a re-occurring problem with ebike hub motors .

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Only when used at higher power than they can handle for the load and situation.

When used within their limits, they can last "forever", other than perhaps eventually replacing bearings, (and in a geared hub possibly clutches/gears if one wears that out).

The shelf of dead motors at Grin is probably mostly from testing to destruction and experimentation, which they do a lot of.

I also have a number of broken motors, and all of them are from pushing them (usually far) past their limits; using them well beyond what they were intended for.

I'm using dual motors on my cargo trike and bike, partly for redundancy and partly for spreading the load among them under stressful situations.


I haven't burned a stator out yet, but I did almost destroy halls in a geared hub by overheating it; they stopped working until it cooled off enough.

If you're having repeated overheating problems, and want to keep using hubmotors, I'd recommend actively cooling the motor during the stressful parts of the ride. Passive cooling like filling it with oil, or statorade, etc., is probably not going to be enough, but it might be.

There is a thread by Justin_LE for Definitive Testing of Heating and Cooling of Hubmotors (not sure of exact title) that has a lot of info about various methods, including actual testing and results, to show what methods might work better for your situation.

To Amberwolf and Neptronics ,,, A Big T Y for both of your replies , gee , would I like to have coffee and a chat with you guys !

Neptronics , I too get that "Stuttering" ,,,, the eZee motor will turn slowly, but when I advance the throttle just a little, that stuttering starts .
What I don't know is when I do a throttle check by swapping out the old throttle for a new Grin T-HTwist_Slim-Long , the motor starts and turns slowly and the 6 blink fault LED (over voltage) comes on when I plug it to the controller . The supplied measured voltage from the Grinfineon 4835 is 5v , as it should be , so where is that overvoltage ?

I got over 600 miles out of the first hub motor , but was enjoying the wonderful new power of the eZee , way too much.

Is there a way to add a thermister heat sensor to the new eZee 250RC before I put it to work ?

The amount of knowledge and experience to keep my ebike going , overwhelms me . Just watching and listening to Justin on U-tube makes me feel so un-educated , Ouch !

Thank Goodness , there are folks like you to help out end users like me .

dwkayaks said:

To Amberwolf and Neptronics ,,, A Big T Y for both of your replies , gee , would I like to have coffee and a chat with you guys !

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If you're ever in Phoenix, you're welcome to come by, as long as you don't mind big shaggy slobbery dogs.

What I don't know is when I do a throttle check by swapping out the old throttle for a new Grin T-HTwist_Slim-Long , the motor starts and turns slowly and the 6 blink fault LED (over voltage) comes on when I plug it to the controller . The supplied measured voltage from the Grinfineon 4835 is 5v , as it should be , so where is that overvoltage ?

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Overvoltage warnings from the controller are about the battery voltage.

Is there a way to add a thermister heat sensor to the new eZee 250RC before I put it to work ?

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If it doesn't already have one, then there's a number of threads and posts about adding thermal sensors (thermistors, KTY sensors, LM35s, etc) to various motors. The thread about testing heating/cooling motors has info too. The hardest part is adding the wires for it, as the wire bundle in the axle probably has no extra room, so you may have to change the hall wires out for thinner ones to make room.


However, since you already know this motor cannot handle your needs in the present form and conditions, I'd recommend any or all of these:

--using a different motor capable of higher power levels at the speeds you run it at

--adding a second motor for those times you have to sustain the higher power levels

--ensuring the bike is geared so you can add your own power sufficient to keep the motor operating within it's limits

--add active cooling for the motor(s), in one of the several ways that's been proven to work for the type of motor involved (geared hubs are harder to cool than DDs, because there are more layers of stuff between the heat source and the outside where heat has to go.

What he said.
Scroll up and read our responses in full before you buy something else.

neptronix said:

You can use the ebikes.ca motor simulator to get an idea of what

32A is a lot for an ezee, but that depends on the volts. Really.. you want to consider how many watts you were throwing at it, not how many amps.. it is a 1000 watt rated motor.

Click to expand...

Just a note on that. It's definitely true that power is the big issue. BUT. Current is what causes I2R losses, and I2R losses are a very big part (often the largest part) of the overall losses in a motor. The reason voltage is so often a factor is that if back EMF increases (i.e. the motor goes faster) then current goes down because there is less delta-V driving current. (I=delta V/R.) Increasing voltage brings the current right back up. So it's accurate to say "more input voltage = more current = more heating." But if you keep the current down (i.e. you limit it to 20A but use a 100V battery) the motor will generally run cooler. (Up to the point where it flies apart from overspeed, that is.)

So if you are burning out motors, and you can limit motor (not battery) current, that can go a long way towards reducing the problem.

For an example:

1.2kW BLDC motor, 72V operating. Losses: Core magnetic losses 50W, copper I2R losses 150W, bearing losses 12W.

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.924.7053&rep=rep1&type=pdf

Ahoy Bill,

( " Increasing voltage brings the current right back up. So it's accurate to say "more input voltage = more current = more heating.")

Interesting , this statement of yours ! I assume that the opposite is true ,,, Less input voltage = Less current = Less heating ?

My wife tells me that the voltage drop or droop which happens when climbing up a hill , allows the current to increase to compensate , thus this extra current burns up the motor . In all my exposure to electrical stuff I have never heard this before and am quite surprised by it , if indeed this is true ????

I did get over 600 miles , mostly towing a trailer , from the first , advertized rated 250W geared hub motor before I cooked it too . You can bet that I am going to treat the new eZee 250RC with heaps of respect and a light hand on the throttle .

Ahoy All , When installing a new T-HTwist_Slim-Long throttle from Grin , upon plugging into the controller , the wheel (off the ground)
starts turning at about 1/4 speed and the Grinfineon 4835 LED fault lite starts blinking 6 flashes an "Over Voltage" warning comes on .

The original Hall throttle works great , but I can't yet figure out just why the new out of the box throttle presents this problem ?????

Any ideas out there how to remedy this problem ?

Cheers , Douglas

..nm..

Hi Douglas,

As your controller is expecting to see an output voltage from the throttle of .9 vdc to 3.6vdc. I'd start by verifying exactly what output yours is giving. By back probing on your throttle's JST-SM connector between the white(sensor output) and black(battery ground) wires with a volt meter, these are the voltages you should be getting when twisting the throttle. From your description with throttle full off, I would suspect your getting ~1.5vdc.

If you wish to try correct it, some things to try...

Mechanically: Check to see that the throttle is able to fully return to the full "off" position. (nothing interfering with the stops or twist operation)
Check to see if the magnet and hall sensor are both in their correct positions...

Electrically: A bad sensor ground wire connection will increase it's output voltage.

To see if it's one or the other... with no magnet in the vicinity, the output should be ~ 2.5vdc.(higher, it's probably electrical.)

For more information on Hall Sensor Throttles see my thread HERE...


Regards,
T.C.

To put it more simply, put 32 amps into that Ezee, and it wants to go a pretty high rpm. Prevent that from happening, with a loaded trailer and a steep hill, and what happens is the excess current turns your coils into a space heater. The lower the RPM, the more of your 1500w turns into heat. Again think of a 1000w space heater, how quick does it get too hot to put your hand on the coils. DAMN quick.

Things vary some with the winding of the motor, but in general, if you fall below 15 mph up a big hill, you are making a ton of heat. Then it just becomes a factor of time,, how long will a coil take to get over 500 F. Longer if the coil is at 32f to start, damn quick if its a hot summer day.

Bottom line, you gonna tow, get yourself a big DD motor, one with a stator more than 28 mm wide, and you will be fine. In my case, I got some old crystalyte motors that tolerate 3000w fine. At 450 total pounds, I had no troubles getting over steep rocky mountain passes at 15 mph. I fed it 2000w, 40 amps of 48v. Bike was 150 pounds with lots of battery, another two for me. Then a hundred pounds of camping gear, including water for a day and night in the desert.


Big motor is what you need, forget the ezee for towing except on grades less than 3%.

Ahoy Guys , T Y all , for your very informative replies , so just following up ,,, Grin found the throttle had a fault and is exchanging it , phew !

As for that eZee 250 RC that I THOUGHT I had burned up , not so !

I opened the motor and didn't get that burned motor smell , but instead found all the stator coils looking new and un-blackened , but haven't checked the Halls yet .

BTW , Grin checked that new 4835 controller , and replied it was in mint condition .

If I find the Halls are good too , I didn't cook that motor as I had thought , and it should work upon re-assembling the side cover , so what goop should I use to put on the mating surfaces ? eZee's goop was a light gray and had almost no squeeze out at the inside edges .