E-bike with motors greater than 250w, speeds above 15mph and the UK police

[Nealh]

The fixation of a more powerful hub and 52/60 + volts batteries will eat in to range as you will be carrying a lot more extra weight to achieve speed, the advantages of these d/d units appear to be that they are cheap however the batteries a decent celled one won't be.
If a rider is happy with 20mph then a good 250w hub and 36v controller can be over volted or use a 48v one with a 48v battery to get this fairly easily, the only factor then to consider is the motor rpm for your terrain and to have a legally marked hub.
In 36v mode;
201 rpm will give 19mph +/- 0.5mph.
260 rpm 23/24mph +/- 0.5mph.
328 rpm 28 mph +/- 0.5pmh.

Above this 48v battery will give you approx. 25/30% more speed and torque with the abililty to still have freewheeling hub should you hit the battery lvc.

 

[anotherkiwi]

The GSM unrestricted with a 36 V battery and the controller at 17 Amps will easily reach over 42 km/h just turning the pedals so that PAS kicks in on the flat.

 

[D8ve]

That's why I keep repeating the phrase "all things considered equal".

For example, speed is a multi-variable function of the form:
y = f(a[1],a[2],a[3],...a[n]), where ...

a[1] = motor wattage (bike spec)
a[2] = motor type (bike spec)
a[3] = rider bodyweight (bike payload)
a[4] = terrain type (terrain)
a[5] = headwind (weather condition)

... and so on and so forth.

Let set 'a' and set 'b' represent the set of inputs for two e-bikes that we wish to compare. If the sets differ only in the first variable (i.e. a[1] and b[1] that represent motor wattage), then the greater the wattage, the greater the speed and the torque and the range. Agreed?

No not agreed.
Fit a mini with a 1200cc bmc engine it will go like stink.
Fit a 5 litre engine then it might also travel quickly but the range will be hammered.
Greater wattage means greater fuel consumption =reduced range.
Are you American by any chance?

 

[Woosh]

then the greater the wattage, the greater the speed and the torque and the range. Agreed?

No.
You can imagine all sorts of functions, they don't make it scientific.
You can estimate your speed using A-level physics, the variables are: controller current limit, battery voltage, battery internal resistance, rider's weight, gradient, air resistance, wheel size, motor torque, motor electrical yield versus RPM (which is a typical sawtooth looking waveform) and finally, road surface friction.
To calculate, you need to have access to the motor test reports supplied by the motor manufacturers for the particular model you want to test. They give you the critical torque and yield figures at different V, I and RPM.

The tool at ebikes.ca has the data on motors already loaded.

 

[Deleted member 4366]

That's why I keep repeating the phrase "all things considered equal".

For example, speed is a multi-variable function of the form:
y = f(a[1],a[2],a[3],...a[n]), where ...

a[1] = motor wattage (bike spec)
a[2] = motor type (bike spec)
a[3] = rider bodyweight (bike payload)
a[4] = terrain type (terrain)
a[5] = headwind (weather condition)

... and so on and so forth.

Let set 'a' and set 'b' represent the set of inputs for two e-bikes that we wish to compare. If the sets differ only in the first variable (i.e. a[1] and b[1] that represent motor wattage), then the greater the wattage, the greater the speed and the torque and the range. Agreed?

it's not nearly as simple as that. If a motor is wound for 201 rpm, it can be a 10kw one, but it won't go faster than 15 mph at its nominal voltage.

The motor winding is the most important characteristic of any motor. Most of all. it affects efficiency and speed.

Then, there's the controller. that's what decides the power, not the motor. Output power depends on efficiency, which depends on the actual speed in relation to the winding speed.

 

[minime]

No not agreed.
Fit a mini with a 1200cc bmc engine it will go like stink.
Fit a 5 litre engine then it might also travel quickly but the range will be hammered.
Greater wattage means greater fuel consumption =reduced range.
Are you American by any chance?

OK, if you solve the equation for range, then the greater the wattage, the greater the range (again, all things considered equal, including average velocity, terrain type, etc). Is that correct?

I am not American. Why made you think that?

 

[minime]

No.
You can imagine all sorts of functions, they don't make it scientific.
You can estimate your speed using A-level physics, the variables are: controller current limit, battery voltage, battery internal resistance, rider's weight, gradient, air resistance, wheel size, motor torque, motor electrical yield versus RPM (which is a typical sawtooth looking waveform) and finally, road surface friction.
To calculate, you need to have access to the motor test reports supplied by the motor manufacturers for the particular model you want to test. They give you the critical torque and yield figures at different V, I and RPM.

The tool at ebikes.ca has the data on motors already loaded.

My function was a generalized high-level example of what a proper mathematical model would be like. The variable list was incomplete and the relationship between variables was not even specified.

Every one of the UK websites I've visited does not mention the motor's manufacturer.

 

[Woosh]

Every one of the UK websites I've visited does not mention the motor's manufacturer.

that's regrettable.
you can always ask here.

 

[D8ve]

OK, if you solve the equation for range, then the greater the wattage, the greater the range (again, all things considered equal, including average velocity, terrain type, etc). Is that correct?

I am not American. Why made you think that?

NO NO NO it's not correct.
The greater the wattage of the motor the shorter the range. More power into the motor means greater fuel consumption.
Listen to people here saying lower power is greater range.

A general assumption about Americans is they like bigger engines and bigger dinners etc.
You seem obsessed with I need a big motor despite advice that it's not nessisarily the best option.

 

[Nealh]

OK, if you solve the equation for range, then the greater the wattage, the greater the range (again, all things considered equal, including average velocity, terrain type, etc). Is that correct?

No.
I have a bike which has at one time or another had a 350 and 500w hub laced in to it both used a 20a controller and the same battery, the 500w either uses more energy or is less efficient then the 350w so mileage per charge is approx. 4/5 miles less.

A 250w hub will have far superior range over a 1500w hub if both used a battery of the same amp hrs and motor winding.

 

[minime]

NO NO NO it's not correct.
The greater the wattage of the motor the shorter the range. More power into the motor means greater fuel consumption.
Listen to people here saying lower power is greater range.

A general assumption about Americans is they like bigger engines and bigger dinners etc.
You seem obsessed with I need a big motor despite advice that it's not nessisarily the best option.

Say you have two bikes with motor wattage 500w and 1500w respectively and you travel at a constant speed of 20mph, which bike has greater range?

 

[minime]

No.
I have a bike which has at one time or another had a 350 and 500w hub laced in to it both used a 20a controller and the same battery, the 500w either uses more energy or is less efficient then the 350w so mileage per charge is approx. 4/5 miles less.

A 250w hub will have far superior range over a 1500w hub if both used a battery of the same amp hrs and motor winding.

So the only reason to get a motor with greater wattage is if you want to reach greater speeds?

 

[D8ve]

Two many variables. But simplistically you can't tell.
And I have had enough of your harping on give me a simple answer when we have already done so.
Some one else who has more patience can try.

 

[Nealh]

So the only reason to get a motor with greater wattage is if you want to reach greater speeds?

I think its already been mentioned lets make it simpler and take a car as an example.
A 4 cyl engine is less powerful then a V8.
A V8 is more powerful then a 4 cyl engine,
One will have more torque/power and be thirstier then the other so will travel far less on the same amount of fuel. One being more powerful that has more torque will accelerate quicker so fuel consumption will also be greater.
The V8 may be faster it may get to A to B quicker but the 4 cyl will catch up and past it for some miles.

If you wish just change 4 cyl for 250w and V8 for 1500w.

As D8ve has said there are to many variables involved on any given course, inclines, start stopping , acceleration, gearing and rider etc,etc.

 

[minime]

Two many variables. But simplistically you can't tell.
And I have had enough of your harping on give me a simple answer when we have already done so.
Some one else who has more patience can try.

Feel free NOT to contribute anymore.

 

[minime]

I think its already been mentioned lets make it simpler and take a car as an example.
A 4 cyl engine is less powerful then a V8.
A V8 is more powerful then a 4 cyl engine,
One will have more torque/power and be thirstier then the other so will travel far less on the same amount of fuel. One being more powerful that has more torque will accelerate quicker so fuel consumption will also be greater.
The V8 may be faster it may get to A to B quicker but the 4 cyl will catch up and past it for some miles.

If you wish just change 4 cyl for 250w and V8 for 1500w.

As D8ve has said there are to many variables involved on any given course, inclines, start stopping , acceleration, gearing and rider etc,etc.

That's why I keep repeating "all things considered equal". Same incline, gearing, rider, etc, etc. Only thing that differs is motor wattage.

 

[soundwave]

http://www.revroll.com/electric-bike/the-stealth-bomber-good-bad-and-ugly

and waight. flat out non stop you be lucky to get more than 15 miles from it.

 

[soundwave]

you need a race bike, bafang hd 1000w with the programme cable and as big as a batt you can put in a back pack like bruno.

i f you over heat the controller a new one can be bought check his vids tho expect hi wear on internal gears doing those speeds.

and you want decent hi end cells not no crap from china out of a skip.
http://www.bga-reworking.co.uk/insat-li-nmc-ebike-battery-10ah-24v-36v-48v.html

 

[anotherkiwi]

OK, if you solve the equation for range, then the greater the wattage, the greater the range (again, all things considered equal, including average velocity, terrain type, etc). Is that correct?

I am not American. Why made you think that?

The greater the Wh of the battery the greater the range. The greater the Watts burnt up by the motor the more tyre smoke

 

[flecc]

That's why I keep repeating "all things considered equal". Same incline, gearing, rider, etc, etc. Only thing that differs is motor wattage.

It seems you are trying to prove a theoretical point, but why bother when it will never happen in practice? If you are serious about owning a powered bike, best to stick the real world situation.

Here's a real world example giving the combined knowledge of the best European manufacturers and countless buyers:

The S class of pedelec was originally only allowed a 250 watt rating for it's permitted 45 kph (28mph). This proved insufficient so the German government where the S class originated upped the allowed power to 500 watts.

The makers all promptly launched 500 watt versions, but they've nearly all disappeared since, with most now being 350 watts. That's because both makers and customers found that to be the best compromise to achieve the speed without unnecessarily losing range due to the higher 500 watt power.

That's it in a nutshell, more power means higher consumption in practical situations, as others have said above.
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