Currie-EZip ebike Kit $289.88 - Amazon.com

[icecube57]

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[DrkAngel]

But from a stand still the motor will draw whatever the motor wants as long as the controller current limit isnt hit. In a stall situation or coming off the line the 9x7 motor will draw up to 130A max at 36v at that point the windings can no longer accept any amps because its being limited by the resistance of the windings.

Which would make them red hot!

So the increase in amp does increase wattage output up to the limitation of the winding in extreme cases.

Actually ... in a "lock test", Increase of amps increases wattage input ... motor wattage output is zero! Heat does not count.

[Hillhater]

The only way to increase watt output on a hub motor is to increase the volt input!
Unless you rewind it?

Volts is pressure, higher pressure = more power.
Volts x Amps = Watts
You can't force in more amps unless you up the volts..
.

Errr ? .. have you never heard of the controller limiting the amps ???
a simple change of controller can double the power output from some stock Ebikes.

[icecube57]

OMG THANK YOU! Hillhater is right putting simple and to the point. You can double the amps and double the output but once the motor tops out in speed then no matter how many amps you use both stock and Super Stock are going to have the same output power due to BEMF but off the line power and acceleration you will see an increase in... input power and true output power at the same voltage with increased amps.

[icecube57]

With increased amps there will be increased losses in the windings as heat but there will also be an increase in output power. The stall represents the total power avaliable off the line if there was no current limit as you proceed up the power band the power output of the unrestricted magic controller motor will be greater vs a current limited motor. And it wouldnt lead to destruction cause you cant escaped BEMF in a motor.

[icecube57]

Output profile of a 30A controller and a 100A controller.

Also a plot of not the input power but the True OUTPUT Power.

This is a 9C 9x7 Hub.

Also the hub with the 100A controller has an increased acceleration from 9.8 secs to reach top speed to 6.1 seconds. My god where is this extra power coming from?

Whats this about the motor not only being able to accept no more than 30A.

[DrkAngel]

Errr ? .. have you never heard of the controller limiting the amps ???
a simple change of controller can double the power output from some stock Ebikes.

If ... the motor is deliberately over-regulated?
So ... one function of the controller is to reduce the amperage to a "safe", reasonable level?

Actually, a higher amperage controller will increase power input, most noticeable in the lower rpm region, where it is least effective, where more amperage greatly increases the percentage of damaging heat, and a comparatively minor increase in power output!

[Floont]

...
The only way to increase watt output on a hub motor is to increase the volt input!
Unless you rewind it?

Volts is pressure, higher pressure = more power.
Volts x Amps = Watts
You can't force in more amps unless you up the volts...

Not entirely true. Most controllers limit the current available to the motor. So, if you upgrade or alter your controller to allow the motor to take as many amps as it demands, then (and only then) is your statement true.

FA

EDIT: PS My above correction is also not entirely true, now that I think about it. You must have batteries that are capable of delivering the current that the motor is demanding too.

[icecube57]

I can post the results for a 5303 that will clearly show an upgrade in amps clearly increases output power.

48v and 60v show drastic changes.

[Floont]

I can post the results for a 5303 that will clearly show an upgrade in amps clearly increases output power...

Beating a dead horse my friend.

If the current (amp) restriction is the motor, then and only then is Drkangel is correct, voltage is the only way to increase power. Unfortunately, the reality is that controllers can and do limit current by design (icecube's point). Upgrading the controller or changing the firmware of the controller to allow more current will increase its power w/o increasing voltage. This situation is very common. I am surprised that Drkangle doesn't acknowledge this fact.

FA

[Hillhater]

Remember DA, we are talking of commercially sold Ebikes ...which have to meet the legal limits, so it is common for manufacturers to install a controller that limits the output to suit the requirements.
Change or modify the controller and suddenly you have more amps available at the motor for either performance.. (or smoke if there is a weak motor also )

[DrkAngel]

Remember DA, we are talking of commercially sold Ebikes ...which have to meet the legal limits, so it is common for manufacturers to install a controller that limits the output to suit the requirements.
Change or modify the controller and suddenly you have more amps available at the motor for either performance.. (or smoke if there is a weak motor also )

I would think it more cost effective, reasonable, to over volt -amp, the more "world standard", 250w motor, than to down regulate a 1000w, or higher, capacity motor?

Magic Pie seems to be an exception, they clearly advertise:
"Description:

* Powerful motor easily works with many voltages without modification; 24 volts outputs 500 watts, 36 volts outputs 750 watts, 48 volts outputs 1000 watts"

Also capable of 250w, presumably at 12v.

One motor-controller, capable of all listed voltages!

[icecube57]

Again we go back to companies not truely having a beefy motor but only swapped out controllers to increase their specs.

GM is a company that will give you data sheets for 36v and 48v but the motors are identical.

The only line of motors where size and weight does play a huge difference is the geared motors. 1 pound can make a huge difference in how much they power can handle continuously. Comparing a 4-6lb 250w model Cute or Bafang motor to a 8lb 1000w puma just isnt fare. In a case like this it would be better and safer to go to the overall larger heavier and beefier motor and derate it than trying to boost a smaller motor more amps or volts to give a better rating

Geared motors tend to be used in production 250w legal bike because watt for watt in most cases a geared motor can produce more torque with less wattage than a DD motor. With that in mind when you are matching this light weight small but shitty motor with a production ebike thats for the average unfit american rider ....they will be lucky to get to 10-15mph by themselves at at the voltage of 24 and 10A its enough to provide the assist to make anyone feel bionic. 250w on a DD hub it lame especially when part of that is just to over come the cogg/drag of the hub.

A 36v or 48v verison of a hub literally has no difference other than the controller in most cases. They arent voltage sensitive but rely on the windings to make the most out of the users situation.

WTH do you even get that its even reasonable to run a hub motor at 12v.

24x10-11A would give you your 250w... excuse me 13-14A if you count your 80% wattage output formula. Thats what would be on most entry level legal production chinese bikes.

[DrkAngel]

Output profile of a 30A controller and a 100A controller.

Have a link to better pictures of "Motor Simulations"?
Can't see to read anything.

[icecube57]

Here.. There .. Everywhere..

If you wanna see a more distict graph i can run it at 48v or select a different motor.

[neptronix]

In a stall situation or coming off the line the 9x7 motor will draw up to 130A max at 36v at that point the windings can no longer accept any amps because its being limited by the resistance of the windings.

Which would make them red hot! They add a fuse to prevent motor burn up.

Do you mean to say that there are fuses in 3 phase hub motors?
I haven't found any in any of the motors i've pulled apart, where are those fuses DrkAngel?

[icecube57]

48v graphs

[icecube57]

5303 Motor at 48v 30A and 100A Controller

[DrkAngel]

In a stall situation or coming off the line the 9x7 motor will draw up to 130A max at 36v at that point the windings can no longer accept any amps because its being limited by the resistance of the windings.

Which would make them red hot! They add a fuse to prevent motor burn up?

Do you mean to say that there are fuses in 3 phase hub motors?
I haven't found any in any of the motors i've pulled apart, where are those fuses DrkAngel?

Search the windings! Most all, should have thermal fuses, look for the odd piece, or pieces, of small tape.
Or, look for the multiple ones in the controller, or, the one in the battery pack.
Internal circuit might have surface mount, resister looking, diodes, with no markings = probable fuse function.
Often there are thermal fuses - self resetting breakers, in-line usually shielded inside a protective tube.

[icecube57]

Ive opened and serviced most common hub motors and several well known controllers from Keywin Lyen Off brands from ebay... ebikekit.. and golden motor... Ive had kit that came with a glass inline fuse... thats about it sir. Out of the many forum pictures ... Do you think you can point out one of these "fuses".

[neptronix]

Search the windings! Most all, have thermal fuses, look for the odd piece, or pieces, of small tape.
Or, look for the multiple ones in the controller, or, the one in the battery pack.

On this forum, you can find reports of BMC, MAC, 9C, MXUS DD/geared, Crystalyte etc. hub motors being fried due the enamel being vaporized off.

I have yet to see a fuse inside a controller designed for a hub motor. If you hunt around enough for pics, you won't see any either.

Please spend more time reading the forums.

[amberwolf]

Search the windings! Most all, have thermal fuses, look for the odd piece, or pieces, of small tape.
Or, look for the multiple ones in the controller, or, the one in the battery pack.

While it would be a good idea to have fuses in many pieces of electronics, lots of them don't actually use any, or at least not where you might expect them. Often this is because a failure that would blow it would happen so fast that the fuse could not blow before the failure was catastrophic anyway. Another reason is it's cheaper not to put them in, by a little bit, and most of these things are made as cheaply as they can possibly get by with, safe or not.

Another really big problem with fuses is that if you use one rated for the max current you would want to preserve electronics at, it won't blow fast enough; if you use one rated to blow fast enough it will also probably blow just during surge currents of commutation, especially at motor startup under load.


None of the controllers that i've got, analog or digital, brushed or brushless, have fuses as such. They limit current by reducing the output pulse widths, or entirely cutting of output voltage when necessary, and if something so rapidly exceeds current capacity of the controller various components can blow up or vaporize, cutting off power, but they are not actually intended to be fuses, though the argument could be made that they might as well be.

In my NiMH battery packs, there are blade fuses, to prevent overcurrent draw on the pack. In the Vpower LiFePO4 pack, no; it has a BMS to limit current and for HVC and LVC, by turning off all the output MOSFETs, but it isn't really a fuse. Again, the semiconductors could blow or the shunts vaporize, but they aren't meant to be fuses, if everything is doing it's job.

None of the battery packs I have for tools, laptops, phones, or anything else have fuses, either. The charging inputs on quite a few devices I have do have fuses, but nothing on the path from battery to device usage point(s). Most of the laptops I've worked on over the years only have fuses on the exterior power input, but once it gets past that point, there are usually not any fuses; the BMS in the battery is usually expected to limit any output, and in a catastrophic situation, the FETs tend to blow, shorted, then often vaporize internally, usually cutting power at that point (and probably faster than a fuse would have anyway).

In desktop computers, the same tends to be true--very rarely have I seen even high-end PSUs or server systems with fuses of any kind (even resettable ones) on the internal power flow path--just on the external power inputs, and sometimes on input devices like USB ports or PS/2 keyboard and mouse ports (because if the wires inside a mouse cable become shorted after fraying from movement, you could have quite the interesting object d' art without any other limits on the resulting current flow ).


While most of the cieling fan, box fan and desk fan motors I've opened up have thermal fuses (or in some cases self-resetting thermal breakers), the small or large power tool motors haven't had them (in the windings; a few have had external current-activated breakers). Sometimes on big ones meant to run nearly continously under heavy loads there are thermal breakers, especially on stuff like condenser motors in refrigeration systems of various types.

I'd expected to find them in the induction motors in the washing machines and dryers I have used for parts, but only one had a thermal breaker in it, the rest don't have anything at all, other than (sometimes) a resettable current-type breaker on the power inputs to the control and user-interface section (but not to the motor power).

But none of the vehicle motors, brushed or brushless, have had them as part of the motors. Would've been nice if they did, since it might've preserved a couple of the ones I've got. Even the larger of the two treadmill motors I've got doesn't, though the smaller one has a thermal breaker that could optionally be put in series with it's power connection (but isn't wired into it permanently, so it can be used without that; I don't know if it was used in it's original product).


So...there *can* be fuses or breakers in batteries, control systems, and motors, but there isn't always.

Most of the places I have seen them used tend to be where outside (wall-AC) high-voltage could, in a series of catastrophic failures, result in contact of that voltage with the user of the product, and where that isn't possible, they tend to be absent. I'm sure that's not a comprehensive rule of thumb, but so far is my experience.

[DrkAngel]

?
Have I got this right?
Simplest - most basic, explanation of how a brushless motor works, is that it runs at full voltage, constantly.
Torque is regulated via modulating the amperage applied to the motor, by the controller.
Speed is not affected, except as moderated by "load".
Application of more amps does not affect, top, unloaded, speed, but is used solely to regulate torque.

Amperage application is unlimited, dependent on controller capacity -
or as a function of thermal decay.
(Thermal resistance of wire increases, as its temperature rises.
The application of more amps, shifts efficiency lower, as heat, to torque, production, ratio, increases.)

Question:
Typical 3 phase BLDC - In the sine waveform charts, amperage application seems, full wave-moderated amps.
Duration regulated, multiple full amp pulses, within each "wave" seems to be a viable method, is that an alternate style of BLDC controller?
?

Thanks, icecube57, for the graphs!

[Floont]

...Torque is regulated via modulating the amperage applied to the motor, by the controller.
Speed is not effected, except as moderated by "load".
Application of more amps does not affect top speed, but is used solely to regulate torque

Your second sentence above contradicts your third sentence above. At full-speed, no-load conditions, it is true that current does not affect (not effect) top speed. However in the real world, as road speed increases, air drag (load) increases with the cube of the vehicle air velocity (ignoring aerodynamics). Your top speed is reached when your torque is in equilibrium with drag (plus minor mechanical losses). So if current, which creates your torque, is limited by your controller, your top speed is artificially reduced.

I have personally experienced this effect on my ebike build when I upgraded my controller so it was no longer the limiting factor on amperage to the motor. The motor now takes as much as my out-dated SLA batteries are able to supply. I gained 3MPH on my top speed when I upgraded just the controller without making any voltage changes.

All that said, certainly increasing voltage has the greatest contribution in affecting top speed. But depending on where your current is being limited, it can also affect your top speed too.

FA

[DrkAngel]

...Torque is regulated via modulating the amperage applied to the motor, by the controller.
Speed is not effected, except as moderated by "load".
Application of more amps does not affect top speed, but is used solely to regulate torque

Your second sentence above contradicts your third sentence above. At full-speed, no-load conditions, it is true that current does not affect (not effect) top speed.
FA

I felt that the "... except as moderated by "load".", extended to encompass the next line.
Perhaps, "does not affect, maximum unloaded, top speed", might be more precise.