Smoked Motor on the "Strong" ebike from department store

I was going to place this in my original thread, then decided its better suited on its own. Luckily I saved all my pics to desktop. Plus copied the text.

I heated this puppy up, after a 30km ride. It wasnt really smoking, just very hot motor.
It took awhile for my first openening of any hub. I took it slow.

So this ride I was on was coming to an end, last small hill before the home stretch. After the motor stopped I hoofed it up 30' to the grass at the top of the hill and touched the motor, it was hot to the touch. I couldnt hold my hand on the hub for longer then 2 or 3 seconds. Newbie mistake on my part, I knew better not to stall it on the hill.

Here are some pictures. Now I have no idea what to do, where to buy parts, nothing. I kind of want to keep this motor, I like it. Its a little loud, people can hear me come up from behind unlike my DD mxus 4506 v2.

This motor originally had 36V lead acid batteries attached to it. I took it up to 49.8V (hoc) RC Lipo, I could get it up to 30km/h, kept up with playground zone traffic easily.





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The motor manually spins good, gears look good. Wires, not so good.
Where do the bare wires go, corresponding to red/black. I think solder back on the bare wire on black side. Its a brushed motor I believe, I had a pic somewhere of the controller clueing into something.

Found it.
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Notice how it says DC Brushes. So its brushed, got "brushes", thats probably where either bare or colored wires go. Be nice to swap out brushes, probably a technical adventure.

edit:
My next step is to open it up even more. Undo those 2 screws slowly and see whats next. Maybe the commutator and brushes etc.
Amazingly this thing is stinking up my house, I bagged it and its sitting outside. Smells like burnt insulation, with a tad bit of oily substance to it. There was grease in the thing.
The magnets look burnt, hope they are alright.

I got this pic here.

It sure looks like toast to me.
Might be saved but you need to look inside.

Dan

100 year old technology.

Brushed motors do not tolerate higher voltages than they’re built to operate. Brushes take a heating when over spec’d such as you’ve done.

If the windings aren’t fried it might work again but it’s probably time to join this century and enjoy the many fine choices of BLDC hub motors.

Overvolting my old brushed motors years ago , I found the same. Just going from 36 to 48v of SLA made them create a lot more heat. With stronger lithium chemistry with less sag I guess the heat is even worse.

Looks like that brush holder got really hot. I'm sure it heated up locally and went before the windings got damaged.

You might be able to find a new brush for it, they are often a fairly common size. But now it looks like you have damaged the commutator, and it tend to spark the brushes more, making heat, pitting it more, etc. So the next set of brushes might just smoke themselves fairly quick.

If you do repair it, 36v.

When I look at the 9 o'clock position in the photo above, it seems to show a lot of damage to the commutator.

You need a 100W soldering iron with a fat tip. If you get a small soldering iron with a "pencil tip", those are for soldering on small leads for resistors, capacitors, etc. No matter how hot you get the tip with a small tip, it will cool down as soon as it touches a larger mass wire. http://endless-sphere.com/forums/viewtopic.php?f=16&t=49848

I'm going to stick my neck out and state that...I "think" that might be repairable. But I agree with dogman, run it at the stock volts, or...upgrade the motor.

The higher volts (going from 36V to 48V) made it run hotter, but in a roundabout way. When switching from 36V to 48V, the motor will "want" to run to a 30% higher RPM, and in order to get there it will apply amps to try and accomplish that. Normally, the amps would drop off to a much lower current when the bike attained a steady state of top speed at "lets just say" 20-MPH. But when running to 48V, it wants to get to at least 26-MPH, so it keeps applying high amps until it gets there (at wide open throttle, WOT). The problem at that point is that the motor is under-sized to maintain 26-MPH, especially if there are any hills that slow it down, so...the 'dumb' controller sends more amps to fix it.

This article may have some useful info, due to similarities.
https://www.electricbike.com/2014-ezip-trailz-lithium/

Buy a brushless DD hub, and post your grin after the first ride. :wink:

I had a brushed crystalyte sparrow motor once and I fried it on a 30 mile journey running it stock with a ping. I got tired of replacing brushes so I sold it. :?

I'm afraid most everyone is correct. While there are modern Brushed motors that can take a lot of heat, (Astroflight comes to mind) your motor obviously cannot. You can get a good brushless kit for a bit over 200 bucks, controller included, and they can take heat better and are more efficient. Welcome to the 20th century. Some of those brushless motors are actually 21st century designs. How do i know abuot brushed designs, you may ask? Ihave 3 old Wilderness Energy brushed motors sitting in my shed. They work fine, but not in the heat that I live in Lower Alabama (LA). Two had their brush holder melt.
otherDoc

Took the other 2 screws off, nothing much behind it really. Everything in the picture shows what needs to be viewed.
But here are some other pictures I snapped on my phone.

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No "Brushes", more like rods. Unless the brushes got burnt off, which is likely...if there were brushes.
There is a spring inside that pushes the square rod up to contact the circle.
The bare copper wire on both sides are connected to their correspond square rod. Which is always in contact with the circle.
Red wire spring is good.
Black wire spring seems weak, but theres not much space. I put it back together and checked it out, its iffy for sure. It needs full time contact and a new spring is definately needed for firm 100% all the time contact.
As well the both sides need more solder. The heat melted it down.

I think for now, I will take a picture of the good red spring to match the black one thats needed., measure it, see if I can draw an outline of it for the spacing between the wires and try to match it up somewhere that sells little springs, almost like toy springs. I will clean it up, and put some new solder on all points, and put it all back together today and give it a go on the weak black spring.

Yeah the commutator doesnt look to well does it.
I will make sure contact surface is cleaned well.

So I soldered the wires back on.
I looked around for some brushes, it looks like what I have doesnt necessarly have what one normally thinks of brushes. Amazingly sears.com sells a bunch.
http://www.sears.com/search=dc motor brushes

Theres a number of factors at work here I think. Maybe the black brush wire doesnt connect to the brush.
Black brush spring doesnt push enough to comutator.
Commutator is fried, it seems sturdy.
I did an ohm meter check and everything matched up. I went comutator to brush, com to brush wire, com to grnd wire, same on red side. All minimal resistance corresponding to material resistance.

Im leaving it be, if I can scrounge up and find a whole new brush peice.

When I put it back together I connected up the 2 leads to about 30V then 45V lipos and the motor would start to wind and stop. So its definately fried.
I just hope the comutator is good and the brushes need changing out. Be good to know the model # of this puppy I couldnt really see any obvious markings.

I will take a closer look some other time.

Those square black "rods" are the brushes. They're made out of graphite that's similar to the lead in a pencil. The springs ensure that the brushes are held firmly against the commutator for good electrical contact. As long as you didn't toast the windings, you should be able to replace the brushes and springs, resolder the power leads, and clean up the commutator to get it working again.

The commutator is the ring of copper contacts that the brushes contact, that can be cleaned up with emery cloth or a strip of sandpaper.

Those brushes look fine, though worn a bit, they probably have 50% of their life left. If the tips are burned, they can be sanded down carefully.

The first problem I see, other than you're using a brushed motor in this millennium, is that the negative brush seems to be stuck. That may mean the spring got cooked. If that happened, replacing it could be trouble. too weak of a spring causes arcing and will burn up a brush and commutator fast. too strong of a spring will grind down the brush and cause a drag on the motor.

Sorting out the problem and replacing the brushes is likey to cost you 1/4 the cost of a new brushless motor in cash, and far more in time. What value do you put on your time?