How did i burnt my bafang motor from overvolting?

[dazzassj6]

Ok i fried my bafang motor PMGR, i thought it was gear stripping until i opened it.

Does anyone know why it was fried? its rated for "36v 200w", the stock controller had 16a max. I overvolted it to 60v, and new controller had a maximum current of 30a

So what did i do wrong?

I remember when I first overvolted it, i went on a steep carpark ramp. Which fully made me notice that something just stuffed up in the motor. I thought this was stripped gear at first but it was not. So the motor probably draw too much current and fried it half of it? But now its fully cooked.

I think i fully fried it, after accelerating WOT at a stop. Could that screw it up since its now 60v @ 30amp???

UPDATE HERE ARE THE PHOTOS

the motor looks 3/4 burnt. some of the coils looks alrite. But i think thats how its not working properly.

gears was not stripped

the casing for the motor looks a bit differnet to the usual gold casing which has exposed coils

the stock gears is different to the SWXB model that voicecoils gave me.

 

[gedemeisterdk]

yes, you probably fried it with too much current. too bad

i have one myself, running a ping 48v with a 14 amp controller, and I think that is stressful enough for the bafang.

these small motors, are not build to handle that kind of amperage, they a rated by the manufacturer for max 48v and likely no more that 20 amps.

over that,at some point, you get gearstripping or fried coils.

get a bigger direct drive motor if you want to go faster/overvolt, i can recommend the "nine continent", perfect size and performance, can be legal at 36v.

 

[dazzassj6]

who makes the "nine continent"???

my stock ebike seller offers to sell replacement wheels with the motor for $200, do you recommend me getting another one? or should i look for other motors?

its a difficult decision.

 

[gedemeisterdk]

hi again

you can get it on ebay:
http://cgi.ebay.com/Electric-Bike-Conversion-Kit-Front-Hub-Motor-w-26-Rim_W0QQitemZ320319686111QQcmdZViewItemQQptZCycling_Parts_Accessories?_trksid=p3286.m20.l1116
(pretty sure its the "nine continent" not polished, (the same manufacturer))
got mine here, but thats in germany:
http://akku-bike.de/akku-bike_Pedelec_Elektrofahrrad_Ebike_Bausatz.html

anyway, have you checked that its not the controller ? or the bms on one of your batteries?
(come to think of it, you have a 10 ah ping battery, according to ping, that battery shouldn't be drawn more than 20 amps cont. (2c))
so check that there is power delivered to the motor.

imho, get another bafang but limit the current to max 20 amp. or look for something else

 

[dnmun]

justin at ebikes.ca has a good deal on the nine continents motor in a kit with the cycle analyst, i think knuckles motor from Grubee is a nine continents, and he thinks the world of it, plus he runs it at 48V i think.

can you take some pictures of the burned up motor? did you see if all the coils are shorted? wonder if you could rewind it. that hot may have ruined the magnets though.

 

[HornetB]

hi again

you can get it on ebay:
http://cgi.ebay.com/Electric-Bike-Conversion-Kit-Front-Hub-Motor-w-26-Rim_W0QQitemZ320319686111QQcmdZViewItemQQptZCycling_Parts_Accessories?_trksid=p3286.m20.l1116
(pretty sure its the "nine continent" not polished, (the same manufacturer))

That one just looks like a Wilderness Energy brushless kit to me without the batteries. Perhaps the motors are nine continients but I dont think they are. Mine is badged with Aotema and looks identical. AmpedBikes and ebikes.ca sell the nine continents.

 

[johnrobholmes]

Did you check the idle amperage on the new controller before zipping away?

 

[John in CR]

...that hot may have ruined the magnets though.

Thanks for reminding me to check that before getting mine rewound after a winding meltdown resulting from improper wiring. I think my magnets are fine though because I ended up using a hydraulic press to separate the magnet housing from the stator. Between the bearing and the magnetic force they just weren't coming apart by hand and I didn't want to lose part of a finger that way.

John

 

[gedemeisterdk]

:

you might be right, they do look alot alike.

but the nine continent is definitely a great motor.

 

[dnmun]

i still think the deal from justin is the cheapest, $405 includes the C'lyte controller and the CA, and someone did the math and the motor was about $205 which is cheap for a DD hub motor, imo. check the numbers and see if he still has the deal at ebikes.ca

 

[dazzassj6]

photos are added

 

[johnrobholmes]

Since all phases didn't fry equally, there is a strong chance that it was phased improperly.

 

[dazzassj6]

Since all phases didn't fry equally, there is a strong chance that it was phased improperly.

it wasnt phased properly? Do you mean that i didnt put the phase wires to the right ones? But it ran smoothly. I followed knuckle's guide, and ran it on over 250km.

 

[johnrobholmes]

So did you hook up a new controller, or up the voltage when it fried? It reads like you did both at the same time and it fried immediately. How long did it ride on 60v and the new controller? What is your weight?


I say it may have been out of phase because all winds did not smoke. Leads me to believe that one phase had proper back EMF, but the other two phases did not.

 

[dnmun]

holmes has a good argument, since 2/3 appear to be burned. but wouldn't it be spread out over all the coils as the motor turned or do you think they all burned in one instant with the reversed phases?
this is the first we have seen of a bafang burning up though, and i know knuckles has run them to 72V already, so i would say the best rational is the reversed phase wires, not 48V.
if it was instant the magnet should be ok since there would not have been time to heat them up so maybe somebody can rewind it yet.
it would be nice to have a source of parts, this one may end up on the for sale page. but the new motors are so cheap in gross quantities. now knuckles has the bearing in the steel gear too.

 

[dazzassj6]

So did you hook up a new controller, or up the voltage when it fried? It reads like you did both at the same time and it fried immediately. How long did it ride on 60v and the new controller? What is your weight?


I say it may have been out of phase because all winds did not smoke. Leads me to believe that one phase had proper back EMF, but the other two phases did not.

it rode like 250km. I changed to a 72v (lvc @ 52v) controller from keywin when i overvolted to 60v. wats EMF? how do i protect them from future frying??

holmes it didnt fry immediately. it ran fine until an incident wen i went up a 30 degrees+ incline, it stuff up my motor. It was chugging at slow rpm, and was normal at higher. So rode like this for another 200km, until i accidentally accelerate at a stop. Thats when it fried the other 1/3 coils. Now running at only 1/3 coils, its not enough power to go anywhere.

Also during the time i stuffed up the first time, after that i cannot turn to WOT or else the controller or BMS shuts the throttle off, or power, then i have to turn the key off and on again. i had to ease thru the throttle.

so is dat why it stuffed up??

 

[Knuckles]

Looking at the burned motor pics the motor looks very different than the Bafang I have.
Your Bafang (36v 200W) is clearly a different model motor from mine (36V, 250W).

It almost seems that the controller shorted the phase connections.
This can occur if the MCU and/or mosfet drivers malfunction if the LVC is set to low.
(The 5V and 12V bus voltage drop too low).
Most of the time this will just blow the controller mosfets.

Also ... Only the Infineon can run the Bafang at over 48V.
Older controllers suffer from "critical frequency" problems at higher voltages.
This will also cause very high current spikes that may also cause winding failure.
Early on I got around this by "overclocking" the original crazy controller.



My Bafang motor will get very warm when I ride it hard at 72V30A.
But for me it has always been Nylon gear stripping which is no longer a problem with the 1-Metal gear.

Tis very sad to see a burnt motor.
You have my sympathies.

-K