I have some questions here that need clarifying. The GNG 48volt 450watt is 750watt if you go by volt and amps. but GNG claims it is some fancy formula that deals with rpm and playing with a online simulator though motors show different wattage at the shaft, waht is at the shart, Canadian regulations measure output for e-bikes st the shaft. This is a link to the similator. http://www.ebikes.ca/simulator/ . I plan on building a midmount in the spring and hopping for a 36volt 500watt at the shaft system.
450 watt is not 450watt it is 750watt is not 750watt
- Thread starter OmniosTom
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wineboyrider
1 MW
A watt is a watt no matter watt! There is only one way to calculate wattage and that is voltage times amperage. So 12v x 20amps is 240 watts and 24v x 10 amps is 240 watts.
Ziggurat
10 W
It does not have to be volts x amps -- a watt is simply a unit of power, Joules/second, energy per unit time, and the Canadian ebike law deals with the mechanical power, as the OP mentioned:
"... has one or more electric motors that have, singly or in combination, the following characteristics:
it has a total continuous power output rating, measured at the shaft of each motor, of 500 W or less..."
Under heavy load, my "350 W" hub motor ebike shows more than 600 W coming from the battery, but with losses, there will be much less at the shaft. From the ebikes simulator, my motor output is at best about 80% of the electrical power in, i.e. about 500 W up a steep hill.
But to me the law is vague due to the two words: "continuous" and "rating". So, do I have to show that my motor eventually burns out if I have 501 W at the shaft? Just about any ebike motor could surge more than 500 W for quite some time. Does a few minutes count as "continuous"? 20 minutes? Then there is the word "rating" -- they could have left that word out and it would have been a physical quantity easily measured, but as a "rating", it sounds like whatever the manufacturer wants to label the motor. Perhaps the power that can be output continuously without starting (slowly) to damage the motor over time?
So I'm not sure how much trouble one can get into based on that "continuous power output rating" clause. If the kit motor says it is rated for 500 W at the shaft, that seems to me to meet the definition (but I'm no lawyer).
"... has one or more electric motors that have, singly or in combination, the following characteristics:
it has a total continuous power output rating, measured at the shaft of each motor, of 500 W or less..."
Under heavy load, my "350 W" hub motor ebike shows more than 600 W coming from the battery, but with losses, there will be much less at the shaft. From the ebikes simulator, my motor output is at best about 80% of the electrical power in, i.e. about 500 W up a steep hill.
But to me the law is vague due to the two words: "continuous" and "rating". So, do I have to show that my motor eventually burns out if I have 501 W at the shaft? Just about any ebike motor could surge more than 500 W for quite some time. Does a few minutes count as "continuous"? 20 minutes? Then there is the word "rating" -- they could have left that word out and it would have been a physical quantity easily measured, but as a "rating", it sounds like whatever the manufacturer wants to label the motor. Perhaps the power that can be output continuously without starting (slowly) to damage the motor over time?
So I'm not sure how much trouble one can get into based on that "continuous power output rating" clause. If the kit motor says it is rated for 500 W at the shaft, that seems to me to meet the definition (but I'm no lawyer).
This is getting interesting, from wikipedia. I live in Canada we use metric.
Units called "horsepower" have differing definitions:
The mechanical horsepower, also known as imperial horsepower, of exactly 550 foot-pounds per second is approximately equivalent to 745.7 watts.
The metric horsepower of 75 kgf-m per second is approximately equivalent to 735.5 watts.
The Pferdestärke PS (German translation of horsepower) is a name for a group of similar power measurements used in Germany around the end of the 19th century, all of about one metric horsepower in size.[3][4][5]
The boiler horsepower is used for rating steam boilers and is equivalent to 34.5 pounds of water evaporated per hour at 212 degrees Fahrenheit, or 9,809.5 watts.
One horsepower for rating electric motors is equal to 746 watts.
Continental European electric motors used to have dual ratings, using a conversion rate of 0.735 kW for 1 hp
British Royal Automobile Club (RAC) horsepower is one of the tax horsepower systems adopted around Europe which make an estimate based on several engine dimensions.
Electrical horsepower[edit]
The horsepower used for electrical machines is defined as exactly 746 W. The nameplates on electrical motors show their power output, not their power input. Outside the United States watts are generally used for electrical power applications.
Units called "horsepower" have differing definitions:
The mechanical horsepower, also known as imperial horsepower, of exactly 550 foot-pounds per second is approximately equivalent to 745.7 watts.
The metric horsepower of 75 kgf-m per second is approximately equivalent to 735.5 watts.
The Pferdestärke PS (German translation of horsepower) is a name for a group of similar power measurements used in Germany around the end of the 19th century, all of about one metric horsepower in size.[3][4][5]
The boiler horsepower is used for rating steam boilers and is equivalent to 34.5 pounds of water evaporated per hour at 212 degrees Fahrenheit, or 9,809.5 watts.
One horsepower for rating electric motors is equal to 746 watts.
Continental European electric motors used to have dual ratings, using a conversion rate of 0.735 kW for 1 hp
British Royal Automobile Club (RAC) horsepower is one of the tax horsepower systems adopted around Europe which make an estimate based on several engine dimensions.
Electrical horsepower[edit]
The horsepower used for electrical machines is defined as exactly 746 W. The nameplates on electrical motors show their power output, not their power input. Outside the United States watts are generally used for electrical power applications.
I guess it's similar to the EU standard, which mentions "nominal continuous rated power", which basically means the label that the motor manufacturer put on it.
The motor standards are designed to stop the motor burning out when the rating is exceeded and to stop manufacturers from over-rating their motors. With Ebikes, it's the other way round, so a motor manufacturer can put a low rating on a high powered motor and still comply with the motor and ebike standards, which I'm sure some have now wised-up to, since we're seeing more and more powerful bikes in Europe with "250w" motors certified to EN 15194.
The motor standards are designed to stop the motor burning out when the rating is exceeded and to stop manufacturers from over-rating their motors. With Ebikes, it's the other way round, so a motor manufacturer can put a low rating on a high powered motor and still comply with the motor and ebike standards, which I'm sure some have now wised-up to, since we're seeing more and more powerful bikes in Europe with "250w" motors certified to EN 15194.
dogman dan
1 PW
Watts in, is always going to be equal to volts x amps in. Only one way to know your true watts in, measure it.
But watts out, is another fish. The steam boiler is a great example, look how many watts in to get 1 hp out.
Complicating matters, is the mas or menos ebike controller ratings. Common 20 amps controllers in many kits are actually 22 amps. Not talking about spike amps before the controller ramps down, 22 amps continuous is seen on a CA if you ride hard up hills steep enough.
I have a "1500w" Chinese controller on my longtail. It's 48v, and 40 amps is seen on the CA under harsh enough conditions. that's a solid 2000w. Odd that they under rated it that much.
Again, that's input wattage. 80% efficiency is about average for ebikes, so 80% of watts in is a safe rule of thumb for watts out, in places where that matters legally. And of course, you are just guessing about input wattage till you break out a meter and measure it. The writing on the controller is just advertising copy.
But watts out, is another fish. The steam boiler is a great example, look how many watts in to get 1 hp out.
Complicating matters, is the mas or menos ebike controller ratings. Common 20 amps controllers in many kits are actually 22 amps. Not talking about spike amps before the controller ramps down, 22 amps continuous is seen on a CA if you ride hard up hills steep enough.
I have a "1500w" Chinese controller on my longtail. It's 48v, and 40 amps is seen on the CA under harsh enough conditions. that's a solid 2000w. Odd that they under rated it that much.
Again, that's input wattage. 80% efficiency is about average for ebikes, so 80% of watts in is a safe rule of thumb for watts out, in places where that matters legally. And of course, you are just guessing about input wattage till you break out a meter and measure it. The writing on the controller is just advertising copy.
whatever
100 kW
- Joined
- Jun 3, 2010
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- 1,297
there are 2 ways to describe power:
1. constant power level ( max amount of power the motor can draw continuously without exceeded a certain temperature)
2. max power level ( max amount the power can handle for a short period)
Finding a relationship between continous power level and peak ( maximum) power level I dont think there is one standard way to do it. There are standard methods used but I cant find in literature ( after many years of searching) any one definition that is used by ebike law makers.
450watt is your continous power level and 750watt is your peak or max. Usually a 450watt continous power rated motor will have a max. power output higher than 750watt, 750 watt peak is more likely to be a 250watt continuous motor.
If any one has any links to definitions relating peak and continuous power levels I would be interested to read them.
1. constant power level ( max amount of power the motor can draw continuously without exceeded a certain temperature)
2. max power level ( max amount the power can handle for a short period)
Finding a relationship between continous power level and peak ( maximum) power level I dont think there is one standard way to do it. There are standard methods used but I cant find in literature ( after many years of searching) any one definition that is used by ebike law makers.
450watt is your continous power level and 750watt is your peak or max. Usually a 450watt continous power rated motor will have a max. power output higher than 750watt, 750 watt peak is more likely to be a 250watt continuous motor.
If any one has any links to definitions relating peak and continuous power levels I would be interested to read them.
dogman dan
1 PW
I'm fairly sure lawmakers don't have the definitions either. 
Or don't fully understand what the engineers told them.
wattage as describing motor ratings are another story from controller specs. Much depends on the definition of continuous, which may be different for different people, or different engineers.
In my mind, continuous use is defined when motor heat reaches equilibrium under a given load. Say the load is one bike, one 150 pound rider, and the load is 20 mph on a flat road. 400w typically. At this load, typical for 20 mph travel, the motor will, on an 80 degree day, reach max temperature of about 120F and then stay there no matter how long you ride.
Can the motor run at 120F indefinitely, hell yes. Almost all hubmotors can do this. So you often see ratings stated as 400-500w. Engineers can agree, that motor x can definitely sustain 400w all day if the rpm is fast enough.
Can you melt a motor with a load of just 400w. Hell yes. Ride up a very steep hill at less than 5 mph, with watts limited to 400w. Most hubmotors will eventually melt, since 200w or more is now made into heat. Heat never reaches an equilibrium in this case, it just reaches about 450F fairly soon and smoke pours out the motor.
This makes a motor rating very hard to pin down. It will do 400w all day at one rpm, but at another will melt in 45 min.
This is why every time people ask"whats the max amps for such and such brand motor?" we start the answer with a lot of "it depends" type prefaces.
Or don't fully understand what the engineers told them.wattage as describing motor ratings are another story from controller specs. Much depends on the definition of continuous, which may be different for different people, or different engineers.
In my mind, continuous use is defined when motor heat reaches equilibrium under a given load. Say the load is one bike, one 150 pound rider, and the load is 20 mph on a flat road. 400w typically. At this load, typical for 20 mph travel, the motor will, on an 80 degree day, reach max temperature of about 120F and then stay there no matter how long you ride.
Can the motor run at 120F indefinitely, hell yes. Almost all hubmotors can do this. So you often see ratings stated as 400-500w. Engineers can agree, that motor x can definitely sustain 400w all day if the rpm is fast enough.
Can you melt a motor with a load of just 400w. Hell yes. Ride up a very steep hill at less than 5 mph, with watts limited to 400w. Most hubmotors will eventually melt, since 200w or more is now made into heat. Heat never reaches an equilibrium in this case, it just reaches about 450F fairly soon and smoke pours out the motor.
This makes a motor rating very hard to pin down. It will do 400w all day at one rpm, but at another will melt in 45 min.
This is why every time people ask"whats the max amps for such and such brand motor?" we start the answer with a lot of "it depends" type prefaces.
el_walto
10 kW
I don't think anyone is very clear on this. I wanted to convert my 5.5hp 49cc scooter to electric, and this is what ICBC in Canada had to say about it.
1500 watt motor from hobby king would be pretty useless, but maybe a 1500watt rated hub motor would be a different story...
1500 watt motor from hobby king would be pretty useless, but maybe a 1500watt rated hub motor would be a different story...
dogman dan
1 PW
Since efficiency is rarely much better than 80% with hubmotors, You can point out that fact, and then set controller and voltage accordingly so you have about 1800w input.
Ask them if that method would work for them. If not, take it to them with 1500w input maximum, get er done, then put the 3000w controller on it later.
Ya simply cannot output more than 1500w, if that's your max input. Heat will always take some, and you can't make energy. Once you have your tags, then modify to what you really want, if 1500w is not enough.
Ask them if that method would work for them. If not, take it to them with 1500w input maximum, get er done, then put the 3000w controller on it later.
Ya simply cannot output more than 1500w, if that's your max input. Heat will always take some, and you can't make energy. Once you have your tags, then modify to what you really want, if 1500w is not enough.
Think I figured it out now 100% sure though. The power in rating may be 500watt put the applied power that the measured at the shaft may be less, I have been checking out some ratings on higher end motors and they show that the input wattage is slightly higher than the rated output wattage. Not sure how it works in the states. The output power can be 100 watts less so more or less looking at the 500 watt motor I was looking at would be a 600 watt motor measured on the input in the USA. This is more reasonable as I have been seeing 500 watt 100 kilo weighing scooters motoring along at 32kmh.