DFT consultation on increase of 250W limit to 500W

guerney

Esteemed Pedelecer
Sep 7, 2021
10,274
3,007
I was amazed at some of the hyperbolic 'danger' talk in the press about increasing average power to a max of 500 watts.
Among other things, fears expressed about batteries being larger, making ebike battery fires even harder to extinguish. Given the choice, people will choose a legal 500W over 250W. Battery failure rates within what passes for a warranty period will be higher if they use the same cheap Chinese cells to power those 500W motors using higher amped controllers - I hope this will force manufacturers of cheap ebikes to use more genuinely capable ebike batteries, but I expect they won't.
 

guerney

Esteemed Pedelecer
Sep 7, 2021
10,274
3,007
Maybe they could be replaced by a Deliveroo collect and deliver service, their typical 'employees' would mostly already have bikes capable of towing a trailer.
I'm sure many cyclists would prefer to have their bodies conveyed to their graves by bicycle trailer - I shall leaflet the local undertakers advertising my new service! Approriately, my Homcom trailer is already painted black. They can't complain about ride quality, but new Homcom trailers have suspension for the same low price.

https://www.amazon.co.uk/HOMCOM-Trailer-Features-Bicycle-Suspension/dp/B0CS8V9LP8/

 
Last edited:

guerney

Esteemed Pedelecer
Sep 7, 2021
10,274
3,007
  • to amend the legal definition of how EAPCs are classified so that the maximum continuous rated power of the electric motor must not exceed 500 watts instead of 250 watts as set out in the current regulations
  • to allow ‘twist and go’ EAPCs to have throttle assistance up to 15.5mph (25km/h) without the need for type approval
Brexit will have been worth it by Jove!
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
20,139
8,233
60
West Sx RH
A 500w EAPC battery will be no different to that which is used for 250w, the main issue is having a battery that whose current output is matched for the controller rating.
 

Ocsid

Esteemed Pedelecer
Aug 2, 2017
441
265
81
Hampshire
Whilst at addressing power, they ought to drop rated maximum continuous power and get something definitive to nail what the maximum legal power is, IMO back to basics for Watts, maximum input volts x maximum input amps.

The wording rated allows the maker to write in any figure they want, and any checking of that is pointless.
Whereas a lab employed by law enforcement courts, can definitively check what volts and amps can peak at with the kit under investigation.
If going that route then the figure should be pitched at the right value for a safe sensibly usable pedal bike..
 
Last edited:

Pingk

Pedelecer
Dec 15, 2023
28
12
Whilst at addressing power, they ought to drop rated maximum continuous power and get something definitive to nail what the maximum legal power is, IMO back to basics for Watts, maximum input volts x maximum input amps.

The wording rated allows the maker to write in any figure they want, and any checking of that is pointless.
Whereas a lab employed by law enforcement courts, can definitively check what volts and amps can peak at with the kit under investigation.
If going that route then the figure should be pitched at the right value for a safe sensibly usable pedal bike..
Motor wattage is a fundamentally flawed method of measuring it's power, Grin has a great article about why it's misleading:


A maximum torque figure would be a more robust measurement (and there are probably better systems than that), but legislators think they understand how wattage works and aren't interested in consulting a qualified engineer.
 
  • Like
Reactions: Az.

soundwave

Esteemed Pedelecer
May 23, 2015
16,242
6,324
my bike with the dongle i have would be classed as r/race class pedelec as can provide power over 28mph.

the sclass model of my motor would be 28mph limited the only difference in the controller is the set speed limit buy bosch that can not be changed the amps for both are the same 20a.


so even if you shunt mod the motor controller you then have to do the same for the batt most so far b4 bricking the bms is 2a more, its just not worth it with this can bus *******
 

Ocsid

Esteemed Pedelecer
Aug 2, 2017
441
265
81
Hampshire
Motor wattage is a fundamentally flawed method of measuring it's power, Grin has a great article about why it's misleading:


A maximum torque figure would be a more robust measurement (and there are probably better systems than that), but legislators think they understand how wattage works and aren't interested in consulting a qualified engineer.
As a Chartered engineer, one pretty well qualified in this very subject, I know that "torque" is not "power", plus I know that Watts is a measure of "power" and the motor of whatever type can't output more power than is inputted to it.
Thus, it is fundamental that if input peak power is measured, there unlike "rated" power there is a definitive measurable basic value, that in turn courts etc could use as legally acceptable evidence. "Rated" power, is simply a nebulous makers rating, anything they wish to credit it with.
The reference article does not refute that, actually it supports "rated" as effectively a useless measure, plus points out that the available power is not necessarily what is inputted, it can't be 100% efficient and that efficiency can vary.
 

Az.

Esteemed Pedelecer
Apr 27, 2022
1,292
585
Plymouth
I live up in the South Tyne Valley near Brampton and Haltwhistle and the hills around here are killingly long and steep. I can ride them with my 250 watt, Bafang crank motor, but it is a matter of bottom gear, a lot of hard work and 3 to 5 miles an hour. By the top - sometimes three quarters of a mile with 1:15 and 1:20 slopes in part, I am breathing like a steam engine.
I would suggest review of your system parameters. It is clearly not up to the job. Reasonable increase of Amps should help. If not, then maybe change of a motor and battery.
Ask Guerney. He should know how to squeeze more omph from Bafang motor.
 
Last edited:

Az.

Esteemed Pedelecer
Apr 27, 2022
1,292
585
Plymouth
"Rated" power, is simply a nebulous makers rating, anything they wish to credit it with.
The reference article does not refute that, actually it supports "rated" as effectively a useless measure, plus points out that the available power is not necessarily what is inputted, it can't be 100% efficient and that efficiency can vary.
Continuous rated power as specified by manufacturer is just a certain class to which motors are assigned to. I don't think there was ever an intention of measuring motor power.
 
  • Agree
Reactions: flecc

Ocsid

Esteemed Pedelecer
Aug 2, 2017
441
265
81
Hampshire
Continuous rated power as specified by manufacturer is just a certain class to which motors are assigned to. I don't think there was ever an intention of measuring motor power.
Agreed, but here the discussion is in revisiting the legislation re pedelec powering, specifically from 250 Watts to 500Watts, and IMO that "power" should be a definitive characteristic that is measurable not a nebulous value a maker marks on their product.
As is, all law enforcers can act on is a labeled value, however indicative that is or is not of what the product is capable of doing. Presently we have something widely exploited, a loophole that when it is revisited ought to be corrected, at least IMO.
 

peterjd

Pedelecer
Sep 18, 2019
195
46
Motor wattage is a fundamentally flawed method of measuring it's power, Grin has a great article about why it's misleading:
A really interesting read - I've taken a copy so that I can read the details a couple of times.
For someone like me, who hasn't had an engineering background, it still seems to come down to the 'suck it and see' approach. I haven't (yet) burned out a motor with my mods. Peter
 

Az.

Esteemed Pedelecer
Apr 27, 2022
1,292
585
Plymouth
Agreed, but here the discussion is in revisiting the legislation re pedelec powering, specifically from 250 Watts to 500Watts, and IMO that "power" should be a definitive characteristic that is measurable not a nebulous value a maker marks on their product.
Clearly intention is to raise power limit. Introducing new power definition would have an opposite effect.

Presently we have something widely exploited, a loophole that when it is revisited ought to be corrected, at least IMO.
Main purpose of this review is political IMO.
 
  • Like
Reactions: Peter.Bridge

saneagle

Esteemed Pedelecer
Oct 10, 2010
4,247
2,097
Telford
As a Chartered engineer, one pretty well qualified in this very subject, I know that "torque" is not "power", plus I know that Watts is a measure of "power" and the motor of whatever type can't output more power than is inputted to it.
Thus, it is fundamental that if input peak power is measured, there unlike "rated" power there is a definitive measurable basic value, that in turn courts etc could use as legally acceptable evidence. "Rated" power, is simply a nebulous makers rating, anything they wish to credit it with.
The reference article does not refute that, actually it supports "rated" as effectively a useless measure, plus points out that the available power is not necessarily what is inputted, it can't be 100% efficient and that efficiency can vary.
Torque is not power, but when you're on the vehicle, it's what you feel as power, as it's the characteristic that determines acceleration.

There is no fixed relationship between input and output power. For any amount of input power, the output power could be anywhere between zero and 80% of it depending on external circumstances - mainly load.

The 250w rated power that we have now and how it has been interpreted and implemented has been about right for a 25 km/h pedal assisted bike. It wouldn't be enough for motors of non-pedal vehicles, like stand-on scooters, to get up steep hills without the addition of complicated gearboxes, so it's a barrier to advance with that type and similar vehicles, and a problem for the technically illegal plethora of scooters that you find in every city that were allowed under some sort of trial regulations.

All that's happening is that they want to make the temporary regulations for those scooters permanent, which will loosen the regulation of pedal assisted vehicles regarding power and control system, but they might have to introduce other rules about traceable ownership or battery certification to alay fears from the general public.
 

flecc

Member
Oct 25, 2006
52,822
30,383
Whilst at addressing power, they ought to drop rated maximum continuous power and get something definitive to nail what the maximum legal power is, IMO back to basics for Watts, maximum input volts x maximum input amps.
We used to have exactly what you want in the 1970s, and even a British Standard defining the permitted power of an EAPC.

But all it did was enforce completely useless assisted bikes with a true 200 watts limit, totally killing the market before it could get off the ground then.

So we scrapped that and cancelled that British Standard in favour of the present system which allows the designer to provide what is needed for the job in hand.

The problem with that old system and what you are asking for is that 200 watts is defined as what an average FIT person can output over two hours or so, and therefore enough for cycling. So even if someone needing assistance can output very little, 200 watts of assistance appears to be enough, so that is where the original law came from.

But of course 200 watts isn't anywhere near enough, we need to allow motors to reach 600 watts or more to be useful in all circumstances, even 800 watts for some purposes. Try to legislate to allow either of these and you wont have to wait long for the storm of anti-cycling protests about allowing three or four times a cyclist's average power. Such a Bill probably wouldn't survive a first reading in the House of Commons.

Hence the law we have, which discretely allows what we need while effectively disguising it with a publically acceptable number.

As it should be, since the job in hand is to provide assisted cycling, not make useless laws to suit courts and ill informed public opinion.
.
 
Last edited:

lenny

Esteemed Pedelecer
May 3, 2023
920
310
The proposed changes would require the government to bring forward statutory instruments to amend the current regulations.
All that's happening is that they want to make the temporary regulations for those scooters permanent, which will loosen the regulation of pedal assisted vehicles regarding power and control system, but they might have to introduce other rules about traceable ownership or battery certification to alay fears from the general public.
"Most SIs subject to the affirmative procedure are laid in the form of a draft SI. They are considered by the Joint Committee on Statutory Instruments (JCSI). The role of this committee is to scrutinise the SI to ensure it is legal and does not go beyond the powers specified in the parent Act."
 
Last edited:

saneagle

Esteemed Pedelecer
Oct 10, 2010
4,247
2,097
Telford
We use to have exactly what you want in the 1970s, and even a British Standard defining the permitted power of an EAPC.

But all it did was enforce completely useless assisted bikes with a true 200 watts limit, totally killing the market before it could get off the ground then.

So we scrapped that and cancelled that British Standard in favour of the present system which allows the designer to provide what is needed for the job in hand.

The problem with that old system and what you are asking for is that 200 watts is defined as what an average FIT person can output over two hours or so, and therefore enough for cycling. So even if someone needing assistance can output very little, 200 watts of assistance appears to be enough, so that is where the original law came from.

But of course 200 watts isn't anywhere near enough, we need to allow motors to reach 600 watts or more to be useful in all circumstances, even 800 watts for some purposes. Try to legislate to allow either of these and you wont have to wait long for the storm of anti-cycling protests about allowing three or four times a cyclist's average power. Such a Bill probably wouldn't survive a first reading in the House of Commons.

Hence the law we have, which discretely allows what we need while effectively disguising it with a publically acceptable number.

As it should be, since the job in hand is to provide assisted cycling, not make useless laws to suit courts and ill informed public opinion.
.
i think still a lot of people don't understand how motors work. 200w would be enough power, but a motor's power varies between zero and 80% of its input power, depending mainly on its speed. If a motor could max out at 200w, it would slow down when it encountered a hill. As it gets slower and slower, the efficiency goes down, and the output power goes down in proportion, so when you need the power the most, you get the least. That's why it's almost impossible to make a regulation for the power.

Most of the above can be overcome with a crank-drive bike if you had low enough gearing, but a twist-and-go scooter doesn't have a crank.

Like you, I'm quite happy with the regulations as they are now for pedal assisted bikes, but I can see that it would do a lot of good to legalise low-power unassisted vehicles. You can see that they're already very popular in cities. Apart from a few press clickbait articles, there don't seem to be too many problems reported. If you can hire one and use it legally, you should be able to buy one and use it too. The main difference is that the present ones are tracked, and the temporary owner is recorded via the app - in theory. I'm going to bet that something like that is coming for us.

BTW, call me a conspiracy theorist, but I watch DJ Audits. He goes round filming industrial estates and has some very entertaining encounters. What I've noticed is the number of data centres there are around the country. Nearly every industrial estate he visits has one, and they have really massive security. They're all brand new too. There were hardly any 5 years ago by comparison. You can use your imagination to figure out what data will be taken, processed and kept. One of them might be where you are on your ebike and how fast you were going. Remember the billions spent on Track and Trace. That wasn't just for covid. In fact, it wasn't even ready for covid. Of course, they can spend the money on it for your health, which is a nice excuse for collecting data on you. How could they otherwise got the budget approved.

As I have a vivid imagination, I can see the possibility that in 10 years time ordinary pedal bicycles becoming illegal because they can't be tracked.
 
Last edited:
  • Agree
  • Like
Reactions: AntonyC and flecc

Az.

Esteemed Pedelecer
Apr 27, 2022
1,292
585
Plymouth
Hence the law we have, which discretely allows what we need while effectively disguising it with a publically acceptable number.

As it should be, since the job in hand is to provide assisted cycling, not make useless laws to suit courts and ill informed public opinion.
and it works quite well through current regulation, common sense and basic physics laws. One can take 250W rated motor and make it work really hard at 750W or even 1000W if it is required with some modifications, but push to hard - lets say to 2000W and you will most likely end up with a burned motor or battery going up in flames, so it all really limits itself well.

Of course it would be nice to tidy up current legislation as it is a one big mess.
 

saneagle

Esteemed Pedelecer
Oct 10, 2010
4,247
2,097
Telford
Of course it would be nice to tidy up current legislation as it is a one big mess.
Jeez! It's not a mess. It's very clear and easy to understand; however, people's thinking is controlled by the paradigm that the power output should be 250w, which seems to prevent them from rational thought.

Lets make it simple. There are two rules about the motor power:
1. The RATED power must be 250w or lower.
2. When the motor runs at it rated power at optimum efficiency, it mustn't burn.

How is that a mess? We don't have to worry about how the motor is rated. That's between the manufacturer and the regulating authorities.

The only thing that needs tidying up is the temporary regulation that allows twist and go scooters from hire companies, but you can't use one that you own.