alfantastic
10 kW
When members talk about stalling a hub motor, do they refer to the point where the motor stops completely, or where the motor operates way below its best efficiency?
Definition of stalling a hub motor?
- Thread starter alfantastic
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MadRhino
100 GW
Stalling a motor is running it slower than it is supposed to, at the voltage and throttle that you feed it. This happens when it is not powerful enough for the task, climbing a hill for an example. If you stall it enough to stop it completely, it 's gonna fry very soon, or the controller will, maybe both.
Drunkskunk
100 GW
It depends on the context. Some use the term to mean a condition where the motor simply doesn't have enough power to turn, like when trying to climb up too steep a hill, or pull too much weight. It can also be used as a term for what a motor will do if the controller losses sync, either due to a bad hall sensor input or a problem with the phase wiring, or an internal fault of the controller, the end result is the motor just "stalls" while riding, much like when a car engine quits while driving.
dogman dan
1 PW
I guess I tend to think in terms of % stalled. You never want it to be 100% stalled for more than a fraction of a second. Example, on some of my extreme hill climb tests, at some point the bike comes to a complete halt. Often it's because I wheelie off, but if not I try to get back off the throttle when the complete stop is imminent. A complete stall may do all kinds of damage to motor and controller.
For typical hubmotor commuters bike kits, a stall tends to begin by about 15 mph when under full load. That's your typical 9 continent, muxus dd, conhis, or whatever kit running on 36v. Full load means you are climbing a hill or hauling a great deal of weight. 15 mph cruising on the flat is not stalled, it's just running the motor slower. Stalled is when the motor is lugging under the load. Towing your buddy back up the hill on his skateboard is likely to be loading it enough to begin to stall.
Slower than that 15 mph under a heavy load, you can see the heat start spiking on a thermometer inside the motor. On a cycleanalyst, you'll see amps maxing or nearly maxing. By 10 mph, I'd call that motor in a definite stalling condition, even if it is only 50% stalled. I really don't know what percentage it would be, but suppose it was 50%. That would mean that 50% of the wattage is making heat. So if you see 900w on a CA, you are running a 450w heater. It will warm up quite quick. Now suppose that 15 mph speed is only 10% stalled. Now it's 90w of heat, and possibly the motor can still shed the head fast enough to keep the motor temps below the melting point indefinietly.
For typical hubmotor commuters bike kits, a stall tends to begin by about 15 mph when under full load. That's your typical 9 continent, muxus dd, conhis, or whatever kit running on 36v. Full load means you are climbing a hill or hauling a great deal of weight. 15 mph cruising on the flat is not stalled, it's just running the motor slower. Stalled is when the motor is lugging under the load. Towing your buddy back up the hill on his skateboard is likely to be loading it enough to begin to stall.
Slower than that 15 mph under a heavy load, you can see the heat start spiking on a thermometer inside the motor. On a cycleanalyst, you'll see amps maxing or nearly maxing. By 10 mph, I'd call that motor in a definite stalling condition, even if it is only 50% stalled. I really don't know what percentage it would be, but suppose it was 50%. That would mean that 50% of the wattage is making heat. So if you see 900w on a CA, you are running a 450w heater. It will warm up quite quick. Now suppose that 15 mph speed is only 10% stalled. Now it's 90w of heat, and possibly the motor can still shed the head fast enough to keep the motor temps below the melting point indefinietly.
dnmun
1 PW
nope, stalled is stalled, meaning it is not moving, that is usually fatal to the controller and the mosfets can burn up in seconds.
cbr shadow
1 kW
Dogman that was a really clear explanation - thanks.
SamTexas
1 MW
I don't know what "stalling" means.
If I have to guess, I would say "stalling" is when the motor reaches a certain low efficiency threshold. Example: Let's say 10%. So the motor is stalling when you only get 10% or less of what you put in. 100W of output for 1,000W input.
But it can't be as MadRhino described. It implies that the only time the motor is not stalling is when it's running at no load (wheel off the ground).MadRhino said:
If I have to guess, I would say "stalling" is when the motor reaches a certain low efficiency threshold. Example: Let's say 10%. So the motor is stalling when you only get 10% or less of what you put in. 100W of output for 1,000W input.
dogman dan
1 PW
Technically true. stalled is no motion. That's why I began to blather about % partialy stalled, to describe what a lot of us use the term stalled to describe.
I would agree, unless a motor is run no load, it's partialy stalled. (still using the wrong word) Perhaps we should be using the term frocking the hubmotor.
Any time you are under sufficient load to cause motor heating that will exceed 200F-300F internally before you finish the ride, you are frocking the hubmotor.
At 10% efficiency, your hubmotor will be thrououghly frocked very quickly. So that's certianly close enough for me to call it stalled. Lots of us ride around with momentary low efficiency, such as a typical no pedaling start. But the "stalling" is momentary enough to do little harm. But you will see higher motor temps when you do a lot of stops and starts, and you will see much higher wh/mi.
But if the hill you need to climb is a mile long or more, you need to stay in the much better efficiency range. Sometimes this can be done by backing off the throttle, then pedaling your guts out using only light assist to get up the hill. But that's no fun! Much better to run the motor at a wattage that gets you up the hill whithout the speed falling off enough to heat the motor up much. This can be done by adjusting volts, amps, or motor windings.
I would agree, unless a motor is run no load, it's partialy stalled. (still using the wrong word) Perhaps we should be using the term frocking the hubmotor.
Any time you are under sufficient load to cause motor heating that will exceed 200F-300F internally before you finish the ride, you are frocking the hubmotor.
At 10% efficiency, your hubmotor will be thrououghly frocked very quickly. So that's certianly close enough for me to call it stalled. Lots of us ride around with momentary low efficiency, such as a typical no pedaling start. But the "stalling" is momentary enough to do little harm. But you will see higher motor temps when you do a lot of stops and starts, and you will see much higher wh/mi.
But if the hill you need to climb is a mile long or more, you need to stay in the much better efficiency range. Sometimes this can be done by backing off the throttle, then pedaling your guts out using only light assist to get up the hill. But that's no fun! Much better to run the motor at a wattage that gets you up the hill whithout the speed falling off enough to heat the motor up much. This can be done by adjusting volts, amps, or motor windings.
TylerDurden
100 GW
IMO:
"Stall" = stopped.
"Lugging" = extended drawing more than rated power (eventual overheat, sans cooling mods).
"Stall" = stopped.
"Lugging" = extended drawing more than rated power (eventual overheat, sans cooling mods).
I suppose the equivalent with an ICE engine is "labouring". I believe the definition is a situation where the application of more throttle doesn't result in an immediate increase in engine speed.
I first learnt about motors/controllers in the context of robotwars. Stalling came under normal operation, and a controller that didn't outlast the motor was considered junk. Hence no one used RC parts
I first learnt about motors/controllers in the context of robotwars. Stalling came under normal operation, and a controller that didn't outlast the motor was considered junk. Hence no one used RC parts
dogman dan
1 PW
Lugging the motor. Or laboring. There's the expression I should have been using all along.
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