Burning smell from HUB Motor

[NCMprague]

Anyone ever notice a burning smell coming from the HUB motor? Smells similar to burnt wires/burnt clutch/burnt something. It happened while I was going uphill for a couple minutes on THROTTLE ONLY. Here is an article that explains what might have happened. Bike seems to be working fine, will test it more later. But I am afraid something inside the motor has already been damaged.

Burning out Bafang hub motors

The short story Bike hub motors can overheat if you work them too hard, too slow. This post is about how motors heat, and how to avoid ...

bruceteakle.blogspot.com

 

[theemartymac]

Almost guaranteed you melted some wiring if you smelled it that clearly. Throttle-only on a long climb is a worst case scenario for most hub e-bikes. It may not fail after one overheat, but a few overheat cycles and the wiring will start to come apart. When climbing under throttle, any energy the motor can't apply via rpms becomes heat. And hubs in particular have a sweet spot in the rpm range where they are producing peak power and little heat. It's usually at a high rpm, so that is why geared hubs were invented so the hub can spin faster at lower road speeds. As you slow down, you MUST throttle back or reduce the PAS setting (or take much more of the load via pedaling) or you will overheat a hub. If you can't finish the climb in a minute or two, you need to plan for a cooling break. Some hubs will hit thermal cutout before the damage sets in, but others will fry themselves happily. The good news is that Bafang cores aren't TOO expensive and can be replaced.

 

[indianajo]

Mac says the winding in their geared hub motor will burn in about 20 minutes of full throttle steep hill. Like people in California trying to go from the beach to the park at the top of the sierra in one run.
5 minutes grade, shouldn't be a problem. You live in the United States, you might be one of those west coast winding burners that electricbike.com told me about. He refused to sell me a mac hubmotor because we have 15% grades in So. Indiana. Short ones, interspersed with 15% down grades. I've got about 1000 miles on my mac12 and no burning yet. Before that 4500 miles on an ebikeling geared hub motor on the same route; that one wore out a reduction gear. There are 77 hills on my 30 mile commute to summer camp, 3 of them 15% and a couple of 10%ers.

 

[NCMprague]

Almost guaranteed you melted some wiring if you smelled it that clearly. Throttle-only on a long climb is a worst case scenario for most hub e-bikes. It may not fail after one overheat, but a few overheat cycles and the wiring will start to come apart. When climbing under throttle, any energy the motor can't apply via rpms becomes heat. And hubs in particular have a sweet spot in the rpm range where they are producing peak power and little heat. It's usually at a high rpm, so that is why geared hubs were invented so the hub can spin faster at lower road speeds. As you slow down, you MUST throttle back or reduce the PAS setting (or take much more of the load via pedaling) or you will overheat a hub. If you can't finish the climb in a minute or two, you need to plan for a cooling break. Some hubs will hit thermal cutout before the damage sets in, but others will fry themselves happily. The good news is that Bafang cores aren't TOO expensive and can be replaced.

Thanks. Assuming I did melt some wiring, or something else, do you think my bike and motor will be fine if I NEVER do the same thing again? I dont know exactly what is the problem, but I do know exactly what caused it (going uphill on throttle only for a few minutes). Bike is only 2 weeks old and I have a 1 year warranty on the motor...

 

[Deleted member 4210]

Thanks. Assuming I did melt some wiring, or something else, do you think my bike and motor will be fine if I NEVER do the same thing again? I dont know exactly what is the problem, but I do know exactly what caused it (going uphill on throttle only for a few minutes). Bike is only 2 weeks old and I have a 1 year warranty on the motor...

Warranties don't cover negligence. Bite the bullet, take it to your LBS, and see if they'll inspect the motor inside to see whats up. Otherwise, how do you plan to handle your next ride, when you might be 15 miles away from home, and the motor bricks on you ? You ready to pedal all the way back, possibly with some mashed gears creating extra resistance ? or a motor that gets locked up, and cant be rotated at all, leaving you to call AAA, or your best friend or spouse, and interrupt their fine day ?

 

[Deleted member 4210]

And if your motor was 350 watts, 36 Volts, and you weigh more than 175 lbs, you had zero business making the motor do all that work. People forget that these are electric ASSIST ebikes. Get the 'assist' part ? Same goes for use of a throttle. Otherwise if you anticipated to be that dependent upon a motor to do so much, you may have been better off buying a moped, designed for motor use all the time. P.S. And not that you wont be, but please be honest with the OEM, and just maybe they will help you out, and supply you with a new motor already spoked into the rim, so your change out is dirt simple. Or maybe even sell it at cost. They arent that expensive. Nothing I hate to see more, than people coming in with an ebike issue, mis-leading about what transpired, and trying to bilk the OEM out of a free replacement opining it 'should be warranty.' LBS's and OEMs can smell this stuff from a mile away. They've seen and heard it all. It's easier to spot what actually happened, than a 2 year old with chocolate frosting on their face, when you ask them what happened to the last doughnut, and they reply "I don't know?" Hub motors very very rarely burn out, smoke, or give off a smell like that. Its far more likely a function of what we call 'pilot error.'

 

[indianajo]

And if your motor was 350 watts, 36 Volts, and you weigh more than 175 lbs, you had zero business making the motor do all that work. People forget that these are electric ASSIST ebikes. Get the 'assist' part ? Same goes for use of a throttle

My ebikeling "1300 W" hub motor, and the 500 W Mac12, will both start 330 lb gross on a 15% grade and push it uphill 100'. That is throttle only, I hated the pas & deleted it. Numbers here matter, 15% grade is 7/8" rise on a 6" level, time up 15% grade about 30 seconds. I consider that non-abuse, dragging that much weight around is one reason I bought a motor. If the original poster dragged 230 lb up a 2000' rise in 30 minutes, then that is serious abuse according to Mac. Not, not.
Plus I hate to tell you, but shorted turns in a motor are difficult to detect. Only a full load test will reveal it as the winding heats up. Torque should be measured as well as current. Shorted turn reveals as watts rise or stay constant, as torque falls to not much. No bike shop has that kind of tester. We used to test pumps back from the motor "rewind" shop by throwing wastewater 20' in the air. If they would squirt 18" above the pipe end, the motor was good.

 

[tomjasz]

Thanks. Assuming I did melt some wiring, or something else, do you think my bike and motor will be fine if I NEVER do the same thing again? I dont know exactly what is the problem, but I do know exactly what caused it (going uphill on throttle only for a few minutes). Bike is only 2 weeks old and I have a 1 year warranty on the motor...

You may be lucky and only need a new set of gears. If it's gear driven.

This is something I see quite frequently. We go eBike and then ride it like a moped. The surest way to kill any number of motors.

 

[NCMprague]

Mac says the winding in their geared hub motor will burn in about 20 minutes of full throttle steep hill. Like people in California trying to go from the beach to the park at the top of the sierra in one run.
5 minutes grade, shouldn't be a problem. You live in the United States, you might be one of those west coast winding burners that electricbike.com told me about. He refused to sell me a mac hubmotor because we have 15% grades in So. Indiana. Short ones, interspersed with 15% down grades. I've got about 1000 miles on my mac12 and no burning yet. Before that 4500 miles on an ebikeling geared hub motor on the same route; that one wore out a reduction gear. There are 77 hills on my 30 mile commute to summer camp, 3 of them 15% and a couple of 10%ers.

Thanks. Sounds like I might need a mac motor for my next Ebike...

You may be lucky and only need a new set of gears. If it's gear driven.

This is something I see quite frequently. We go eBike and then ride it like a moped. The surest way to kill any number of motors.

thanks. The bike seems to be running fine. Im guessing the only way to know if I need a new set of gears or anything else is to have it inspected by a bicycle shop. What are the symptoms if I did need a new set of gears? Louder noise? Slower acceleration? More burning smells?

 

[theemartymac]

Don't stress about it for now, just ride it and see. If you don't find any difference in performance and the smell does not return you might be fine. If you find it overheats more easily now, or burns battery faster, makes less power, etc, that is an indication that you partially cooked the windings or the wiring. There isn't much if anything you can do to repair minor damage to the windings or the internal cable, just do your best to avoid the damage in the first place, and replace the hub or core once it finally goes.

 

[NCMprague]

And if your motor was 350 watts, 36 Volts, and you weigh more than 175 lbs, you had zero business making the motor do all that work. People forget that these are electric ASSIST ebikes. Get the 'assist' part ? Same goes for use of a throttle. Otherwise if you anticipated to be that dependent upon a motor to do so much, you may have been better off buying a moped, designed for motor use all the time. P.S. And not that you wont be, but please be honest with the OEM, and just maybe they will help you out, and supply you with a new motor already spoked into the rim, so your change out is dirt simple. Or maybe even sell it at cost. They arent that expensive. Nothing I hate to see more, than people coming in with an ebike issue, mis-leading about what transpired, and trying to bilk the OEM out of a free replacement opining it 'should be warranty.' LBS's and OEMs can smell this stuff from a mile away. They've seen and heard it all. It's easier to spot what actually happened, than a 2 year old with chocolate frosting on their face, when you ask them what happened to the last doughnut, and they reply "I don't know?" Hub motors very very rarely burn out, smoke, or give off a smell like that. Its far more likely a function of what we call 'pilot error.'

I paid for the bike so I have EVERY RIGHT DOING whatever I want #FACTS ... And I’m only 160lbs for the record...