"True" Power Rating of 48V1000W Yescom Kit

[wesnewell]

Well, that's not entirely true. While increasing voltage will increase both speed and acceleration, increasing only the amps will increase acceleration, and loaded speed. As for the ratings given by hub motor manufacturers, I tend to think it's an input rating since it's given in watts. It's very easy to message this with a simply watt meter. How will you measure the output wattage to know if you've exceeded specs without special equipment? You can't. So an output rating is basically useless.

 

[DrkAngel]

Well, that's not entirely true. While increasing voltage will increase both speed and acceleration, increasing only the amps will increase acceleration, and loaded speed. As for the ratings given by hub motor manufacturers, I tend to think it's an input rating since it's given in watts. It's very easy to message this with a simply watt meter. How will you measure the output wattage to know if you've exceeded specs without special equipment? You can't. So an output rating is basically useless.

Once again! Please realize that "watts" are a measure of energy, all types of energy including mechanical energy, not solely of electrical energy!

The output rating is all that matters!
The only input ratings I have seen are the Amps Volts and Rpms, to produce maximum power output (hp).
That is your maximum possible output power.
Typically obtainable somewhere in the 50 - 80% of no load speed range. (it varies by motor design)
Efficiency is the name of the game.

If input watts were all that mattered then the cheapest, crappiest, least efficient motors would be all that anyone wanted. More watts is better ! Right?
The ones that give you the least range from your battery! ... ???

But yes ... more amps will increase acceleration, at low speed anyhow. You can dump in gobs of amps and get some better acceleration.
As I noted before, a 1000w motor at 25% speed and 1000w input might output 500w of power, you could dump in 2000w and get, possibly 750w of power.
Problem is instead of 500w of power and 500w of damaging heat ...
you are getting 750w power and 1250w of damaging heat.
50% more power for 250% the damaging heat.


Or ... you can forget all this and just text any motor companies support site and ask them if their 1000w rated motor is rated by input watts or output watts.
Might be best to contact multiple, likely, you will have trouble believing until receiving an overwhelming number of responses.

 

[parajared]

Over-amping and overvolting both yield higher thrust levels. I suspect that Drkangel does not live near any hills or have a programmable controller to observe this phenomena yet.

 

[DrkAngel]

Over-amping and overvolting both yield higher thrust levels. ...

Agreed. Never said anything otherwise.

I've been running a 24V motor at 37V for 5 years now. 3500+ miles, with no problems, and
Posted plans for 2 - 44.4V Magnum builds, using 24V motors.
Also posted plans for running a 24V motor at 22.2V for lower speed, great torque and hill climbing, then "shifting " to 44.4V at 1/2 the amps for high speed road cruising.

I merely pointed out that adding amps at lower speeds gave a little more torque and a lot more damaging heat.

As for overvolting ... I encourage it.
I also pointed out that if you run a 48V 1000w motor at 60V it effectively is a 60V 1250w motor.

It is even a common practice for some companies to sell the same motor as a:
24V 500w motor;
36V 750w motor;
48V 1000w motor.
Only changing the controller.

 

[dogman dan]

And that is talking about a motor/controller systems rating. Slightly different from a discussion of what the max wattage a particular motor can tolerate.

FWIW, the original question was what the actual max wattage of a particular kit was, theoretically. Or more simply, what amps controller do I have? In this case, sold as a 1000w kit, it is obviously in reality a 1500w kit if it has a 30 amps controller and you attach a 48v battery.

But in the real world, you might not see that full 30 amps for much duration. So they called it 1000w, presumably because it uses about 1000w while cruising full speed?

 

[DrkAngel]

Getting nowhere so I sent out some emails to eBike companies.
ebikes.ca
ampedbikes.com
sdelectricbike.com
Will try to find more with English support.


"Watt Rating - Input or Output"

"We've been having a bit of a debate as to what is meant by the watt rating on an eBikes motor.

Original question involved a 48V 1000w rated motor.
OP expressed delight that his motor measured a drain exceeding 1500w and deduced that they accidentally sent him a 1500w motor?

3+ views emerged:
1. rated watts indicate input watts
2. rated watts indicate output watts
3. rated watts is continuous usage limit
4. miscellaneous musings
Other?

Such a divergence of conflicting opinions, among supposedly intelligent forum members, is disconcerting.
Could you tender an authoritative voice?
Reliable sources, technical references, available?

PS Discussion Location - "http://endless-sphere.com/forums/viewtopic.php?f=2&t=47518""

Will post replies, if they are not posted by companies.
Different manufactures, good technical sources?
Please email them a copy of above!

 

[speedmd]

I understand motor power by definition to be output power.

From the Eng. tool box, motor power is calculated " The horse power of an 230 V electrical motor with 85% efficiency pulling 10 amps can be calculated as: Php = 0.85 efficiency x 230 (V) 10 (amps) / 746 = 2.62 (hp) (Key is efficiency, the output power/ input power)

Good article. ftp://ftp.cs.rochester.edu/pub/archives/rec.woodworking/woodwork-motors

They suggest that hp / power claims for electric motors are all "S1" continuous duty rating. "Constant load sufficient duration to reach thermal equilibrium".

If they are claiming 1000 watts and it is the motors maximum output rating or something else, it would be poorly (misleading) specified.

 

[DrkAngel]

Getting nowhere so I sent out some emails to eBike companies.
ebikes.ca
ampedbikes.com
sdelectricbike.com
Will try to find more with English support.


"Watt Rating - Input or Output"

"We've been having a bit of a debate as to what is meant by the watt rating on an eBikes motor.

Original question involved a 48V 1000w rated motor.
OP expressed delight that his motor measured a drain exceeding 1500w and deduced that they accidentally sent him a 1500w motor?

3+ views emerged:
1. rated watts indicate input watts
2. rated watts indicate output watts
3. rated watts is continuous usage limit
4. miscellaneous musings
Other?

Such a divergence of conflicting opinions, among supposedly intelligent forum members, is disconcerting.
Could you tender an authoritative voice?
Reliable sources, technical references, available?

PS Discussion Location - "http://endless-sphere.com/forums/viewtopic.php?f=2&t=47518""

ebikes.ca - reply ...

"Hi Walter, the confusion here is that there is no such thing as a 'rated watts', hence you'll notice that we never talk about an explicit wattage rating for any motors on our site. In the context of a permanent magnet motor, you can only give a nominal 'rating' if you also constrain or specify the motor RPM and allowable temperature rise, which no one really does. The same motor that does 500 watts at 200 rpm, will do 1000 watts at 400 rpm for the same internal heat buildup, and it will do 1000 watts at 200 rpm as well just with a faster rate of heat buildup. What someone decides is it's "rated power" is entirely arbitrary.


Actual wattage (for input or output) is very exactly defined. For any given motor, your maximum output power will depend mostly on your battery voltage and controller current limit, and only less so on the motor itself. Rated wattage of a motor doesn't really mean shit. It's only used for marketing, leading people like the OP being confused or delighted as the case may be, but leading to very little useful insight or data about a particular motor itself.


End of story. Feel free to quote me verbatim wherever the post may be!


-Justin"

Arrrgh!
#1 reply seems to be sympathetic to the controversy ...
But rather than clearing things up ... might have muddied the waters even worse?

 

[Dauntless]

Arrrgh!
#1 reply seems to be sympathetic to the controversy ...
But rather than clearing things up ... might have muddied the waters even worse?

I rather liked it. I mean, confusion seems to be the definitive answer on this subject.

 

[wesnewell]

roflmao. From the ebikes.ca website.
Item 9C 280X Front 9C 280X Rear Clyte HS22 Front Clyte HS35 Rear Clyte 54XX Rear
Relative Power* ~600 W ~600 W ~450 W ~750 W ~1200 W
Wheel Quality Poor Poor OK OK Good
Spoke Size 13g 13g 12g 12g 12g
Rim Width 24.5 mm 24.5 mm 29 mm 29 mm 35 mm
Disk Caliper Space Poor (14.5mm) Poor (15.5mm) Good (18mm) Good (18mm) Good (18mm)
Paint Job Flakey (black) Flakey (black) Nice (dark grey) Nice (dark grey) Nice (black)
Hub Weight 5.9 kg 6.0 kg 5.5 kg 7.5 kg 13.5 kg
*Relative power is just a ballpark number for what the hub can produce continuously at ~300 rpm without any risk at all of overheating.

It only stands to reason that there has to be some rating on a motor. Otherwise how would one know how many volts and amps to feed it. Watts being VA is the perfect rating. All general purpose motors I've seen in my 66 years have had ratings in one form or another. At least their site agrees that it's a continuous usage rating, which I've been saying from the beginning.

 

[Gregory]

But rather than clearing things up ... might have muddied the waters even worse?

Not at all, I think Justin has chosen his words very carefully and concisely. There is no confusion here.

....What someone decides is it's "rated power" is entirely arbitrary. .....

.....Rated wattage of a motor doesn't really mean shit. It's only used for marketing, leading people like the OP being confused or delighted as the case may be, but leading to very little useful insight or data about a particular motor itself.

It's just a made up "safe" number the seller says you can run the motor at, unless you're ian.mitch (sorry Ian, I couldn't resist).

 

[DrkAngel]

It seems that legal definitions of ebikes rate the motor watts as output power!

Laws - Legal limitation of motor by watt output.

Australia - "... power output not exceeding 200 watts"
New South Wales - "... maximum engine output is less than 200 watts"
Victoria - "... provided the motor's maximum power output does not exceed 200 watts."

Canada - "an attached electric motor of 500W or less"
Alberta - "... providing they do not have assisted speeds higher than 32 km/h (20 mph), or an electric motor producing in excess of 500 Watts (0.671 hp)."
Nova Scotia - "a power-assisted bicycle as a bicycle with an electric motor of 500 watts or less,"
Saskatchewan - "must have engines with 500 watt power or less"
United Kingdom - "require that the motor has an average power output limited to 200 W (250 W for tricycles and tandems),"
EU-definition electric cycle - not universal but " 250 W on bicycles" is common
India - "Vehicles with below 250W"
New Zealand - "with motor output power of less than 300W are classified as "not a motor vehicle". "
United States - "an electric motor of less than 750W (1 hp),"

Worldwide, the watt rating is output watts - horsepower.
As the standard, for legal - legality purposes anyhow.
I would have to expect that anything sold, rated for legal use anyhow, would use this same output watt = horsepower standard!

 

[speedmd]

the confusion here is that there is no such thing as a 'rated watts

What would you expect. You pick out a less than correctly worded question and do not want to get nailed down while running by the seat of the pants. . It is not rated watts, it is more exactly "rated power".

We can most all agree that "POWER" rating is OUTPUT POWER. All motors are like this. The only one caring what the input horse power is, is the guy bringing in the hay to feed the horses. Seriously, electric motors are required to give the input voltages and current so you can properly size the feed circuits without burning down the neighborhood.

Motor Rated power must specify the input power (voltage * amps) required to make that power continuously without worry of burning up at a steady load. If it is not a S1 continuous rating, it should be noted as "peak power" "developed power" or some other madison avenue bullshit they come up with to confuse you into thinking your 6 amp hand saw is a real 5 horse power.

This brings up a great point. The real duty cycle that hub motors may see with regeneration braking may be much more severe and should require including (x) amount of repeated stops with e-braking, and starting from a stop (y kg load at z V*A in) without overheating into the duty cycle specifications to give a more real world indication of what kind of real world power to expect. I think this is what we should be asking for, but am not holding my breath for the answers.

 

[DrkAngel]

Finally decided to go to the source.
Contact:
yescomusa.com

"48V 1000W

We are experiencing some confusion - disagreement as to the watt rating of your kit.
Your 48V 1000w kit.
Is the 1000w:
the peak output watts (hp) or
peak input (electrical) watts or
sustainable output watts or
sustainable input watts?

Your reply would be greatly appreciated!
DrkAngel"

Tried to keep it as simple and direct as possible!

 

[wesnewell]

Yescomusa is just an online big box store. If you want real answers you will have to go straight to the motor manufactures. And then you probably will get an answer from a help desk which will probably be wrong.

 

[DrkAngel]

Most members respect the ebikes.ca "Hub Motor and Ebike Simulator".

I thought it would be appropriate to use it to test the eBike "watt rating" theories.

1. open ebike calculator in separate window
right click, "Open link In New Window", here
2. "Open System B"
3. Configure all factors identically
Golden 500W = (500w rated)
36V 12Ah SLA
except Controllers
System A = 35a
System B choose custom and set to 100a (or 75a) added - beyond 75a controller contributes absolutely nothing!
4. click "Simulate"
PS I set "mph" under "Chart Options"



Things to notice:
At 12mph full throttle both output at the maximum 500w, efficiency is at 50%, so ... 1000w input for 500w output.
Going from 35a to 100a controller (red lines) shows only a fractional-minimal power increase, and only at the bottom of the power curve. (A maximum 500w output from a 36V 100a controller, a potential 3600w input!)

At 1mph
35a controller uses 1219 electric watts to produce 68w output watts & 1151 watts of damaging heat
75-100a controller uses 2208w electric watts to produce 94w output watts & 2114 watts of damaging heat

At 5mph
35a controller uses 1056 electric watts to produce 280w output watts & 776 watts of damaging heat
75-100a controller uses 1626w electric watts to produce 360w output watts & 1266 watts of damaging heat

Continuous run (full throttle) "breakpoint" occurs at (700w input 450w output or 250w continuous heat dissipation.)
"Continuous run input wattage" is not a limitation, rather, continuous-average wasted wattage (heat) is.
Avoiding damaging heat production?
Moderate amp input at low speeds (limited throttle or wimpy controller if you have no self control.) or ...
Limit time at low speed - substantial pedal assist getting up to efficient speed.
Combined - pedal assist with moderate throttle recommended!
Get a good run at hills, continuous pedal assist and finally, reduce throttle as speed decreases.

0% additional contribution beyond a 75a controller.

Golden 500W @ 36V looks pimped for the US market with a precise 20mph capability!

Notice the shift in efficiency produced by varying the throttle percentage!
Throttle reduction mimics lower voltage, or effectively reduces voltage to motor.
(Seemingly negating some advantages I envisioned for a 22 > 44V "shift".)

Last effort at trying to explain-prove watt rating-usage ...
so please don't criticize my views until trying the ebikes.ca "Hub Motor and Ebike Simulator", as described above --- DrkAngel

 

[geeeyejo1]

Original question involved a 48V 1000w rated motor.
OP expressed delight that his motor measured a drain exceeding 1500w and deduced that they accidentally sent him a 1500w motor?

Although indeed delighted; I didn't think they had accidentally sent me a 1500 watt motor - rather that the controller provided allowed more amperage allowing the motor to go up to 1500 watts. I really had concerns that due to my weight (230 lbs), I wouldn't be able to hit or maintain the top speed of 27mph. The bike easily does that and with pedaling hits 30mph. For $230 (Cyber Monday discount) this was a tremendous value for the performance of this kit!

 

[DrkAngel]

Original question involved a 48V 1000w rated motor.
OP expressed delight that his motor measured a drain exceeding 1500w and deduced that they accidentally sent him a 1500w motor?

Although indeed delighted; I didn't think they had accidentally sent me a 1500 watt motor - rather that the controller provided allowed more amperage allowing the motor to go up to 1500 watts. I really had concerns that due to my weight (230 lbs), I wouldn't be able to hit or maintain the top speed of 27mph. The bike easily does that and with pedaling hits 30mph. For $230 (Cyber Monday discount) this was a tremendous value for the performance of this kit!

Please examine the post directly above.
It demonstrates that the "rated watts" is the output watts ... not the input watts!
"True" Power Rating "Watts" - Demonstrated!

 

[geeeyejo1]

Original question involved a 48V 1000w rated motor.
OP expressed delight that his motor measured a drain exceeding 1500w and deduced that they accidentally sent him a 1500w motor?

Although indeed delighted; I didn't think they had accidentally sent me a 1500 watt motor - rather that the controller provided allowed more amperage allowing the motor to go up to 1500 watts. I really had concerns that due to my weight (230 lbs), I wouldn't be able to hit or maintain the top speed of 27mph. The bike easily does that and with pedaling hits 30mph. For $230 (Cyber Monday discount) this was a tremendous value for the performance of this kit!

Please examine the post directly above.
It demonstrates that the "rated watts" is the output watts ... not the input watts!
"True" Power Rating "Watts" - Demonstrated!

Got it - whatever this motor is actually putting out, just damn pleased it is getting my fat a-- up to nearly 30mph!

 

[migueralliart]

I run mine at 12S lipo with a 50 amp controller all day long.

Currently vented plus upgraded phase wires. Also installed a temp sensor switch with a buzzer and it has never gotten hot to activate it.

People seriously underestimate these kits. They can put out some good amount of power down.

 

[geeeyejo1]

I run mine at 12S lipo with a 50 amp controller all day long.

Currently vented plus upgraded phase wires. Also installed a temp sensor switch with a buzzer and it has never gotten hot to activate it.

People seriously underestimate these kits. They can put out some good amount of power down.

What top speed are you getting with that setup?

 

[justin_le]

OK, time to wade in these muddy waters...

All general purpose motors I've seen in my 66 years have had ratings in one form or another.

Indeed they do, but this is because the general purpose motors that you've dealt with are designed to plug into a wall outlet or DC source that pretty well defines their operating RPM, hence they can very reasonably say what the sustainable continuous output power ought to be. For instance your 1/3 HP AC induction motors are expecting to run at 120V and 60 Hz, and your car windshield wiper motors are expecting to run at 12V etc.

However, if you take the 1/3rd HP induction motor and supply it with 240V and 120 Hz from a variable frequency drive, then it can suddenly generate twice as much continuous power no problem, and the nameplate wattage doesn't match up with anything. Similarly, if you spin it from a low frequency 30Hz signal for a slower RPM, then you would eventually burn up the motor if you loaded it down to produce its 'rated' 1/3rd HP. Hence a "power rating" on a motor without a context of the operating RPM has little meaning.

With general purpose motors, that operating point (volts, amps, frequency) is usually implied or it is also stated on the label too. The continuous wattage value is an associated byproduct of this, it's not an intrinsic property of the motor itself. With an ebike hub motor, the effective voltage can be all over the map (depending on the user's pack voltage and their throttle setting) and hence the power output capability is all over the map too.

It only stands to reason that there has to be some rating on a motor. Otherwise how would one know how many volts and amps to feed it. Watts being VA is the perfect rating.

For sure there are ratings associated with a motor. The two most valuable ratings to understand a motor's characteristic and power handling capability are the winding resistance and the kV constant.

Watts by itself is one of the worst ways of rating an electrical motor without additional context. But it is also the most intuitive for people to understand, and so it will persist. It has a good ballpark meaning to convey the overall size of a motor, but shouldn't be taken as some kind of literal value. And you should also avoid relying on it when comparing between manufacturers, since the exact same motor could be called 500W by one producer, while another might call it 1000W, and both would be correct and could justify their 'rating'.

And on that note, you should _definitely_ not use power ratings when comparing between vendors, as most vendors really don't have clue! This is why I say the power rating is mostly a marketing term than an engineering one. Look at what happened to the air compressor and shop vac industries where power ratings and "Peak HP" got taken over by marketers:

http://www.truetex.com/aircompressors.htm
http://www.kevinsbrady.net/motors.pdf

At least their site agrees that it's a continuous usage rating, which I've been saying from the beginning.

The number 1000W doesn't derive from any exact methodology regardless of what they say on their site. Put a temperature sensor in the motor, and run it _continously_ (say for several hours) at 1000 watts of output power, and you will likely be surprised at how the inside temperature just keeps going up, up, and up to quite an uncomfortable degree, and then starts releasing smoke. In practice though, you would have fully drained your battery pack before this point and so it is of little practical concern. So the word "continuous" in the realm of ebikes is another vague and imprecise word, just like "rated power", and so to talk of "continuous rated power" is doubling up on the vagueness!

I hope that helps a bit, but the best thing to do is understand permanent magnet motor operation, and then the 'rated power' really ceases to come into the picture. If there was a power rating value that was meaningful in and of itself, it is not the mechanical output power of the motor, but the maximum thermal power (from I^2R) that the motor can dissipate without overheating. -Justin

 

[dogman dan]

To me that unmuddies the water.

What I find most important is not so much what wattage you are running, but how inefficiently you are doing it. That's what led me to love the slower windings for the kind of steep singletrack, or flat but deep sand, riding I have locally. With the slower windings, I get less better efficiency at lower rpms.

I'm in the inefficient rpm range so much riding here, that I can easily smoke a motor anyday, and get saved only by not carrying enough battery to get that hot. I could increase efficiency a lot by riding faster, but I hate crashing above 25 mph. Or I could run smaller rims, but I like 26" for rolling down rock staircases.

IMO, 1500w isn't excessive for these motors for a moderate length ride. In summer I run 1500w of controller, but in cold weather when cooling is quicker, I can get away with 3000w. To my mind, talk about watt limits needs to also include consideration of weather conditions.

Why yescom doesn't market the kit as 1500w beats me. But it's a great way to fool a buyer into trying to run it with a too small battery.

 

[speedmd]

Motor that can dissipate x amount joules may be most important, no doubt, but wrapping my head around properly sizing a motor to do a job efficiently, not sure I can adapt to quickly.
I still want to see as much of the details as I can get hold of. Safe usable power band is very important on any vary speed application and brings in a good point on low rpm specifications/ limits/ expectations. Regenerative Braking adds additional heat/ strain and should not be overlooked. With some agreed upon levels and methods we may have most of the makings to set the defacto ISO "performance standard" for ebike hub motors.

 

[DrkAngel]

To me that unmuddies the water.

What I find most important is not so much what wattage you are running, but how inefficiently you are doing it. That's what led me to love the slower windings for the kind of steep singletrack, or flat but deep sand, riding I have locally. With the slower windings, I get less better efficiency at lower rpms.

I'm in the inefficient rpm range so much riding here, that I can easily smoke a motor anyday, and get saved only by not carrying enough battery to get that hot. I could increase efficiency a lot by riding faster, but I hate crashing above 25 mph. Or I could run smaller rims, but I like 26" for rolling down rock staircases.

IMO, 1500w isn't excessive for these motors for a moderate length ride. In summer I run 1500w of controller, but in cold weather when cooling is quicker, I can get away with 3000w. To my mind, talk about watt limits needs to also include consideration of weather conditions.

Why yescom doesn't market the kit as 1500w beats me. But it's a great way to fool a buyer into trying to run it with a too small battery.

Partial throttle can shift the efficiency range lower!
No need to go faster to hit efficient range.
See ebikes.ca "Hub Motor and Ebike Simulator"
Slide throttle % and watch efficiency range shift!

If you want to put a sustained watt limit on a motor you would have to rate by waste heat, that is the only way to measure sustainable heat tolerance.
For example, assume a 500w? heat tolerance, 1000w sustained input at 50% efficiency would be tolerated, 500w motor output and 500w heat production.
At top speed 80% efficiency 2500w sustained input would be 2000w motor output and 500w heat production.
Dogging it up a hill, at 33% efficiency 750w sustained input would be 250w motor output and 500w damaging heat.
Watt input is a factor, but heat production watts is ... "the factor!"
"Hub Motor Ebike Simulator" - link above provides a power output heat - output scale for different speeds, throttle etc.