Should it be legal....?
- Thread starter indalo
- Start date
So,
37 volts x 17A, gives a peak draw from the battery of 629 watts.
By EN15194 the Motor Continuous Output rating must be limited to 250 watts, and if measured at the output shaft,
Combining the 10% and 5% measurement allowances, then a measured continuous output of 289 watts would just pass. 629 watts from the battery with 289 watts out implies an overall efficiency of 46%. Is this low efficiency correct?
Are the motors are being run above their rating (perhaps just for short spells which would be fine for a short hill)
If the overall efficiency is higher than the 46% which I calculate, then is there a risk of burning out the motor windings on a long hill at maximum power?
Perhaps SGS did the alternative test of acceleration over 20 metres, in which case I guess that if power comes on very slowly then a 629 watt bike could pass that test.
Unfortunately David's test certificate gives no clue about exactly how SGS did their power test.
It seems that Scottyf's comment at post 18 is right on the money.
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And I'm A Fackin Ole Can according to some yob who didn't like the way I pushed my Ikea trolley. Far from taking offence, I was highly amused. You need to give criticisms weight according to your own opinion of the critic; in this case it was zero.
Absolutely, a point I've made in here many times previously. The continuous power tests are a sham, passing motors which patently don't get near to meeting the legal provision. The only time that motors actually met the requirements of the law was in the earliest days of e-bikes and as one would expect their performance was pathetic. That was the major reason why the gestation of e-bikes took so long originally, with two wasted decades. It was only when manufacturers started to supply motors that performed sufficiently well that e-biking started to succeed.
In reality many "legal" e-bike's hub motors can run continuously at double the legal rating for the whole of their battery content without harm and a few can greatly exceed this. But they pass the EN15194 tests!
So if my 500w rated BPM hub was running on my 12A rated 36V controller (as it will be) and i 'claimed' 46% efficiency, i could re-label the motor '250W' fit a pedelec sensor, do anyway with the throttle and i could be technically legal, although i wouldn't have a certificate to say so?
The above is a bit of a dodgy way of doing it though.
And I don't think legal anyway.
Sorry I didn't mean to swear in my previous post. But it does sum up alot over the 250w rating system. The only real version is the speed. The rest should be allowed because it holds no weight.
But let's say you wanted to hit the 250w system. You run a motor at 24v and 10amp peak which would be awful unless you had it drive though gears so you keep it in the peak longer.
Otherwise it's going to run at around half that wattage which would mean by the time your using it it would have just enough to outweigh it's own drag and weight.
As flecc says, rendering it useless for practical use.
And I don't think legal anyway.
Sorry I didn't mean to swear in my previous post. But it does sum up alot over the 250w rating system. The only real version is the speed. The rest should be allowed because it holds no weight.
But let's say you wanted to hit the 250w system. You run a motor at 24v and 10amp peak which would be awful unless you had it drive though gears so you keep it in the peak longer.
Otherwise it's going to run at around half that wattage which would mean by the time your using it it would have just enough to outweigh it's own drag and weight.
As flecc says, rendering it useless for practical use.
I agree, just playing devils advocat....
to have the rated power of an ebike motor which remains at thermal equilibrium seems a daft way of rating output of a motor when power demand is so variable, i understand it works ok for industrial applications, but not as a means of regulating power (law wise) for transport machines.
Internal Combustion Engines aren't rated this way, they are rated peak power/torque.
to have the rated power of an ebike motor which remains at thermal equilibrium seems a daft way of rating output of a motor when power demand is so variable, i understand it works ok for industrial applications, but not as a means of regulating power (law wise) for transport machines.
Internal Combustion Engines aren't rated this way, they are rated peak power/torque.
I asked the question because the way I read the EN spec and the allowable 20m acceleration test a 37v bike at 17amp would not pass. If you check the various power graphs available for typical geared hub motors peak current draw occurs around 65~70% efficiency. Given the 10% allowable EN power tolerance and working backwards the controller needs to be limited to no more than 12amps.
Unless Wisper use some sort of ramped power control I can't see how they would pass EN using the acceleration test. As stated previously the EN spec and the 'legal' positioning is at best a sham as Flecc states.
Unless Wisper use some sort of ramped power control I can't see how they would pass EN using the acceleration test. As stated previously the EN spec and the 'legal' positioning is at best a sham as Flecc states.
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That, of course, is one of the costs of regulation - development and innovation is limited and, in many cases, stymied.
As someone else pointed out, calling the libertarians among us fascist is kind of ironic. After all, if Hitler was back which side do you think would be telling Jews they had to wear the yellow star because it is the law, you know.
There, that has definitely invoked Godwin's law, even if eddieo's post did not.
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Hi 10mph this is correct, most medium/high end pedelecs will peak at higher power than the specified 250W for very a short boost. If they were continually run at such high current the motor would burn out or in most cases a safety control would cut power to the motor.
All the best
David
I totally agree Scotty, the 250W limit is misleading and in my opinion ill advised however I agree with the 25kph limit. If we could increase the power to 1hp as in the USA we could build useful cargo/post bikes etc and get even more vans off the road.
I would also welcome the opportunity to introduce a second class of pedelec in the UK (as in Germany) that will excede 25kph and would be treated in law more like a moped. I am almost certain this would pull many who want to run their pedelecs at ilegal speeds back into the fold. The cost of insurance would be minimal, road tax would be free, the wearing of an uprated cycle helmet would be acceptable and an anual MOT type safety check would be welcomed by the industry as a whole.
All the best
David
I can't find fault with those proposals David. Does BEBA have an official position on this matter? If not, I think they should.
Regards,
Indalo
Hi NRG, you are correct, we do use a very sophisticated acceleration control on all our new bikes, we call it "soft start". It keeps us within EN19154, decreases the possibility of wheel spin on take off especially in the wet and holds the power back so the motor safety circuits do not recognise this surge as an over load and turn off the power.
All the best
David
I see not much evidence of libertarian values on here just selfish Hedonism from some quarters. anyway Libertarian sounds to American to me, in that they probably preach one thing and do exactly the opposite. Without social structure and decent laws, we would still have hanging, racism, back street abortions, out of Europe etc ..etc..The mind boggles
D
Deleted member 4366
Guest
I think we had most of those things in the '50s/'60s. I think there's quite a lot of people that thought it was better then than now - including me!
Hanging innocent people? - No thanks
The mindlessness of racism? - No thanks.
Back street abortion consequences? - No thanks.
Out of Europe? - Not sure that we ever really went in, would have been nice to have tried it.
D
Deleted member 4366
Guest
What about hanging guity people?
What about mindful racism. Not all racism is bad. Do you remember when we used to parade around school waving the Union Jack on empire day. Also, cheering for England in a football match is racism.
Not sure about backstreet abortions. At least they used to pay. Now its us that have to pay, but I suppose that's better than us having to pay to raise the child.
Out of Europe we were an extremely successful manufacturing and trading country. I don't think we could survive on our own now.
What about mindful racism. Not all racism is bad. Do you remember when we used to parade around school waving the Union Jack on empire day. Also, cheering for England in a football match is racism.
Not sure about backstreet abortions. At least they used to pay. Now its us that have to pay, but I suppose that's better than us having to pay to raise the child.
Out of Europe we were an extremely successful manufacturing and trading country. I don't think we could survive on our own now.
Nothing wrong with hanging guilty people of course, indeed I think people should have that as an option instead of life imprisonment. But innocent people cannot be unhung, and we hung too many innocent people.
Please take the following in the right spirit, I'm not trying to be a smartass, but the term for what you've said about pride in your race is racialism which is entirely legitimate and like you, I'm all for it.
Racism is the expression of superiority of one race over another, usually by discrimination, and it's that I hate.
Europe is very much a matter of personal opinion of course, but I don't think we can blame Europe for our manufacturing demise. Our clinging to outdated designs and practices, aided by our backward British trade unions did that. Inept British governments had a hand in it too.
.
Please take the following in the right spirit, I'm not trying to be a smartass, but the term for what you've said about pride in your race is racialism which is entirely legitimate and like you, I'm all for it.
Racism is the expression of superiority of one race over another, usually by discrimination, and it's that I hate.
Europe is very much a matter of personal opinion of course, but I don't think we can blame Europe for our manufacturing demise. Our clinging to outdated designs and practices, aided by our backward British trade unions did that. Inept British governments had a hand in it too.
.
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