9c motor wearing out? Increased heat: *I figured it out*

[parajared]

Well I have been loving my new e-bike, and in the month I have had it I have already logged 60 miles on my 9c hub motor commuting to work during the week, and playing on the trails on the weekends.

My motor is starting to run into problems however. I typically draw 40-45 wH per mile and average about 20mph. At first I was drawing 50 wh/mi to maintain the same speeds but as of late I am drawing 60 wh/mi, averaging 15 mph, and running hot. The motor has more of a whine to it than normal when I accelerate.
When I lift the rear tire and spin it, I the tire does not continue to spin like it used to. It seems to be encountering some drag. I have completely unbolted it to see if it is getting pinched and just let it hang from the torque arm and it still seems to drag.

My commute to work hasn’t changed any, my batteries are still in good shape (I keep a close eye on them with my battery balancer and cycle analyst), I haven’t been exceeding dogman’s suggestion of 1500watts to the hub, the brakes aren’t rubbing. Perhaps the bearings are going out?
Any suggestions before I crack the motor open and take a look?


Ok, I figured it out. I read this article here: https://sites.google.com/site/shelbyele ... -hub-motor
and saw the picture of the hub, and realized my hub looked like that. The article says:
"You can see on Nicobie's hub here that the copper windings are blackened. It's not the copper itself that burned, but the thin layer of varnish insulation that burned out and shorted the windings together. This kills the hub motor.... The hotter the copper gets, the farther apart the copper atoms and their electrons are. This results in less conductivity; meaning, even less efficiency and MORE heat."

[Ykick]

Basic check would be unplug phase connectors to rule out something in the controller. If condition persists then try to visual phase wires entering axle for melting/shorting. Bearings of course can fail but rule out controller and wire insulation first.

EDIT - and this is DD (direct drive) motor?

[neptronix]

any rain exposure?

[dogman]

Okay..... Lets have all the details, because 45wh/mi is insanely high for 20 mph. Could be your CA is calibrated wrong, or maybe you are running something odd, and have the wrong, but still running forward halls and phase combinations.

If so, you could have damaged your controller. Lots of cogging could be a phase short, but odd that it runs at all if that is the case, whether in the windings or the controller fets. Any chance of a nicked wire at the axle?

Not that it's impossible to wear out a motor fast, I've done it in less than 40 min three times now. But not by cruising at 20 mph.

[parajared]

Yes, I think my CA is miscalibrated because earlier it said I was getting 27aH out of my 20aH batteries. I need to browse the forum or fiddle with the thing to figure out how to get it re-calibrated. This is a direct drive motor with no rain exposure during my usage. I also bought it used, so no telling how much actual mileage is on this motor. I should also add that I have tried my other phase wire on it to no avail. It just so happens that I have another controller, I will swap controllers when I get home to rule out controller malfunction.

[itchynackers]

You need to get that CA calibrated for sure. After that, post up your no load current and speed at full throttle.

[pwbset]

45wh/mi is insanely high for 20 mph

Not if you're climbing a bunch of hills. My commute averages 55wh/mi+ going 18-20mph.

[chilledoutuk]

45wh/mi is insanely high for 20 mph

Not if you're climbing a bunch of hills. My commute averages 55wh/mi+ going 18-20mph.

that's strange don't you also save a lot power going back down those hills?

I mean i personally just coast down most hills which other than using regen is probably the most efficient way and not much slower in my case as i have a 6x10.

[parajared]

dogman wrote:
45wh/mi is insanely high for 20 mph

Pwbset wrote:
Not if you're climbing a bunch of hills. My commute averages 55wh/mi+ going 18-20mph.

Pwbset may be right. Half of my commute is tarmac with mild hills, the other half a hilly dirt trail. I'm always amazed at how much a difference just dirt makes on the amperage draw.

[pwbset]

that's strange don't you also save a lot power going back down those hills

I'm a bit weird in that I climb 1,600ft on the way up to work, but it's all in one stretch. I don't do any regen, but I did use a plug brake with the motor quite a bit.

[dogman]

That's why I wanted the details. If he's climbing steep enough hills to be pulling 45wh/mi he could be cooking his motor.

If he's pulling 45 wh/mi cruising 20 mph on the flat, not towing a trailer or riding a 300 pound bike, then that is a horribly wrong number.

Used motor. It's toast if those numbers are correct. Or, as I suspect, it's got the wrong hall sensor and phase wire sequence, and it's just making heat. Or both problems are present.

[parajared]

Ok, just connecting my other esc wasn't as easy as I was thinking. It looks like I would have to cut into the wires to make that work. I have reset the CA from the settings that it used to have to all it's default values and made sure that the wheel size was entered in correctly. I have examined the wires going to the hub and found no damage, I will commute to work tomorrow on my bike and see if the numbers change at all.

My guess is that may be a burnt motor or bearing because the hub is acting like it always has the brakes on. I don't think it's the controller because it is cool to the touch after a long ride and CA says I can pump a pretty steady steam of electricity out. I don't think it's phase wires bases on the temperature of the wires compared to the temperature of the hub. I also don't think it's phase wire or hall sensor sequence, because the problem has been slowly getting worse and worse over the course of a week. Testing phase wires and hall sensor sequence looks really tough to me but I imagine I could hook my volt meter to each hall sensor lead to at least see that each lead is getting voltage.

[MadRhino]

My guess is that a bearing is shot.

[amberwolf]

Regarding your motor getting hotter and taking more power--have you checked your brakes for rub, both on that wheel and the other one? ALso checked your wheel bearings, both in the motor and the other wheel? Any of those could cause enough drag to contribute to motor heating and inefficiency. Low tire pressure also does this, if it's dramatically lower.

[dogman]

Now I'm getting more confused, I thought you said the wheel spins normally with no drag. Which I thought eliminated bearings and shorted phases.

Low enough tire should also be easy to notice. But that will do it, I sure melted a motor trying to finish the death race heat with a low tire. But that was slowing to a crawl for the corners and then going back to 45 mph.

Again, more details are needed. What are you doing, with what, at what voltage, etc etc etc. You got us not only guessing, but guessing with no info. We have no idea if you are cruising along the flat at 20 mph, or towing a trailer up steep hills.

If you have a bad bearing, that will be fairly obvious once you remove the cover. Stick a finger in the hole, spin the cover, and any crunchies will easily be felt. You could have a motor cover rubbing the frame or something, right next to the axle but generally that makes obvious noise and is noticed.

[John in CR]

My guess is that a bearing is shot.

+1 My 9C came with bearings that were pretty awful from the getgo, and I can see a change in the resonance as bearings really go. Of course, running a 9C at 40-50wh/mile is pushing it a bit hard. Has the no load speed changed? If its gone up then the magnets are damaged.

[parajared]

John in Cr wrote:
Has the no load speed changed? If its gone up then the magnets are damaged

I will start checking no load draws. My current no load= 156watts or 3.55 amps at 44 volts

MadRhino wrote:
My guess is that a bearing is shot.

I was unable to get the gear off of the chain side to check the right bearing but the left bearing seemed in decent enough shape: no grinds or clicks. Seems to spin along nicely. I will do some research on how to get the freewheel off of the other side and take a look at that one too.

amberwolf wrote:
Regarding your motor getting hotter and taking more power--have you checked your brakes for rub, both on that wheel and the other one

Yes, the front wheel spins nicely without any drag but the rear wheel (the hub motor wheel) will not spin for long after spun. I have compltely disengaged the rear brake to rule out brake drag and it does not make a difference in drag. I have put my ear next to the brake pad and I can't hear it dragging when the brake is on (but not engaged). I turned off regen and when riding the bike when I let off the throttle it slows down like a brake is on.

parajared wrote:
Yes, I think my CA is miscalibrated because earlier it said I was getting 27aH out of my 20aH batteries.

I think I have the CA calibrated correctly now. I followed post where Itchynackers wrote "If one shunt is approximately 4.8mohm, then for a 12 fet with two shunts: Resistance should be about R = 1/(1/4.8 + 1/4. = 2.4mohm"
I changed my CA to these settings and my electricity discharged to ah charged back up match up now. Also my on paper math matches my CA readings (20ah x44v= 880watt hours. Discharging batteries from full charge to empty 880wh consumed in 1hr for 16 miles=55wh/mi)

Dogman wrote:
Again, more details are needed. What are you doing, with what, at what voltage, etc etc etc. You got us not only guessing, but guessing with no info. We have no idea if you are cruising along the flat at 20 mph, or towing a trailer up steep hills.

My commute to work is a 8.7 mile stetch of highway shoulder to a 7.3 mile stetch of dirt trail. Hills are mild but the entire trip climbs in elevation from 4,500 ft to 5,400 ft (900ft total). I am a 215lb rider on a Giant Revel mountain bike. Tire pressure is a touch on the soft side for street and a touch hard for the off-road segment. No trailers pulled, no dumbells strapped to the handlebars.
Lyen 12 fet
9c motor
44v (12s lipo) setup
26" 1.95 tires
20mph average to work 25mph on return trip
last readings (with CA properly calibrated) on 5/2/12= 50.1 wh/mi to work 38.7 wh/mi back home (10mph tail wind)

Whew, what a mouthful! I appreciate all the comments guys, and I will have some pics up soon

[parajared]

I have a setup that has been getting 45wh/mi on average on flat ground. 215lb rider 20mph average on a mountain bike frame with a 15 lb battery configured in a 12s (44volt) setup, cycle analyist is set up properly. No trailers or anything extra, just a ca and a bike.

I keep running my 20ah batteries all the way to low voltage cutoff on my 17 mile commute to work. I am faced with either buying more batteries, or getting a more efficient hub.

I have heard that you can discover where the ineficiencies are by feeling where the heat is after a long ride, and in this case it would seem to be in the hub. My hub has been making a growling noise, but that went away after I smeared grease all throughout the hub.

The brakes are not rubbing, the wires and speed controller all stay cool, it's the hub that gets hot. I have a feeling I am putting something like 500watts into forward motion and 500 watts into making a lot of heat.

Any recommendations before I toss this hub in the trash?

[Tench]

Is it a sensored hub? Growling and using too much current could be the result of a dodgy hall sensor? its only a couple of minutes job to test them.

Simon.

[ZOMGVTEK]

If the motor is sensored, are you sure you have the right hall/phase combo? Color to color is not necessarily the right way, even if its a kit.

45wh/mi at 20 MPH is roughly twice what it should be. It's very unlikely your motor is that inefficient, unless something is really wrong. The growling noise can be a sign.

[Ykick]

What kind of hub are you dealing with and how many Ah does the CA show used when you reach LVC?

EDIT - thanks deVries, thought the username seemed familiar. Now I get it, perhaps a merge would be best?

[deVries]

Did you lose your recent 1st thread about this same topic???

This one:

9c motor wearing out? Increased heat, drag, amp draw

Folks were waiting for answers from you there???

[dogman]

Well, trying one more time to help, If your motor is getting really hot running 20 mph on the flat in little wind, something must be wrong. False phase order that still runs forward makes heat in the motor and blows controllers. So that could be one thing. Another one could be, you cooked off the motor and won't tell us about that day, when you climbed that hill towing somebody.

I just looked at a motor like that last week for a guy. He killed that motor towing another bike, but very wierdly, it still ran. Ran rough though, and sure enough the phases were shorted. Just turning it, it cogged like the phase wires were touching.

[parajared]

Is it a sensored hub? Growling and using too much current could be the result of a dodgy hall sensor? its only a couple of minutes job to test them.

Simon.

I read this post here viewtopic.php?p=82465#p82465
and repairing/wiring/testing hall sensors looks like a royal headache.

Maybe I need lyen's hall sensor checker, and a bit more knowledge on hall sensors.
viewtopic.php?f=31&t=20413

How does one check/swap a hall sensor anyway. Is it just soldered to the magnets or something?

Also yes Dogman, I have gotten the motor pretty roasty during my hillier trail rides.

[ProDigit]

You know,
When the motor has several wires connected to the controller, I would measure them all.
If one is not broken (and the others trying to compensate for that one, then perhaps a mis wiring, or a broken controller.

Also possible is that dust got in your wheel, together with the oil/grease. Sometimes using the wrong grease causes more damage than do good.
If there's sand in the drum, and you add oil to it,it'll become a sticky mud of sandpaper, filing down whatever there's inside.
Open it up completely.
There's a possibility that one of the coils got burned.

Buying a new wheel should be fairly easy!