Bafang 8fun CD 36v or 48v ?
- Thread starter Rohloffboy
- Start date
To some extent it is but not limited to the ebike industry. I worked with signal amplifiers in China the output power in certain models i.e. 20dbm and 24dbm would have the same components, the controller determined the output. The manufacturing cost the same but the retail price very different.
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It seems that although the law has been draughted with lots of 'wriggle room', which helps no-one, except the lawyers (no change there, then).
Have there been any recent cases in UK courts, of which anyone knows about?
Have there been any recent cases in UK courts, of which anyone knows about?
I was wondering that legal question myself from my research zero prosecutions but i may be wrong.
What I can tell you it is not illegal to sell a mobile repeater but in the uk it is illegal to install yet many installations in the uk but zero prosecutions.
I would think within reason the eapc will be the same. Not in the public interest.
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What I can tell you it is not illegal to sell a mobile repeater but in the uk it is illegal to install yet many installations in the uk but zero prosecutions.
I would think within reason the eapc will be the same. Not in the public interest.
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D
Deleted member 4366
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Noone for an over power bike, but there was a woman prosecuted for using an electric sit-on scooter. It was the type with very small wheels and no pedals. It seems that she was warned not to use it because of the lack of pedals, so she had too blts welded to the front wheel so that it could just about pedal at 1 mph. The court decided that it couldn't be pedalled properly, so she was convicted,
There was a guy convicted. I can't remember the story, but he was caught totally drunk on it a couple of times before they decided to prosecute him for his own safety.
There was a guy convicted. I can't remember the story, but he was caught totally drunk on it a couple of times before they decided to prosecute him for his own safety.
I'm curious because the power to shift my 250lbs/113kg weight, plus the bike, is my main worry. Speed is a secondary issue, although it would be fun to be able to temporarily de-limit the thing, under appropriate circumstances.
I'm at the research stage at the moment, although I'm edging towards the crank driven motors as opposed to front/rear wheel motors for my conversion bike.
It seems that Bafang/8-Fun has the market pretty much sewn up in terms of crank kits, but where to buy is now becoming a concern, since no-one seems keen to respond to their potential customers! I'm even considering setting up my own conversion kit import and retail business, as there is very clearly an opportunity to do it better than that which seems currently available...
You might find this interesting if you haven't already seen it.
https://electricbike-blog.com/2015/06/26/a-hackers-guide-to-programming-the-bbs02/
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Johnny, have you tried em3ev in China, I found them very good at responding, and will probably place my order with them for the Bafang 8fun CD and battery when I have fully made my mind up.
Hi trying to clarify all of the above. The electric motors in bikes are just a subset of general electric motors and the following is of general application
Torque relates to motion in a circle
Torque is measured in Newton . metre
When a torque is applied and the shaft rotates one revolution the work done or absorbed is. 2 xphi torque And is measured in joules . Work is measured as a force x distance and the distance in this case is the circumference of a circle of radius 1 M.
If the shaft rotates done revolution in one second the power is now 2*phi*torque watts. . If the shaft rotates faster then the power transferred is greater.
Torque can be changed up and down by using gears or pulleys or chain drives.
For any given electric motor, the torque is proportional to the current applied... Not the voltage.
However in order for this current to flow a voltage is required so indirectly torque depends on voltage.
when a voltage is applied to an electric motor, current flows in the windings and in reacting against a magnetic field, either produced by another current or even the same current acting in another coil or by a permanent magnet creates a torque.
Whether this creates rotational motion will depend on whether the torque produced exceeds the frictional losses and the inertia of the load. If the load is excessive, then the motor does not turn , no mechanical work is done and all the electrical power is consumed within the motor as heat. If the torque is sufficient, then the motor rotates and accelerates until the work done on the load equals the mechanical work done by the motor.
In all cases some electrical power is consumed by the motor in resistance heating of the windings, frictional ... Both in the bearings and in the air windage, and in iron losses in magnetic fields.
In a lightly loaded motor, the motor accelerates until the back EMF, equals the applied voltage. Back EMF is proportional to rotational speed, so the bigger the voltage the faster the speed.
Motor s will have been designed to operate at specific voltage , current and power ratings. They consist of windings embedded usually in epoxy resin and a laminated iron core.
If the motor is stalled or forced to run at a low speed, the current in the windings will heat up and melt.
If the motor is made to run too fast, the friction in the bearings will cause heating
If the magnetic field is to high for the amount of iron used, then the core overheats.
If the motor includes a gearbox, it will likewise have rotational speed and power levels specified. torque in excess of its design limits will strip the teeth from the cogs or cause premature wear.
Motor manufacturer s are aware of all these and will issue a power rating for their motor and designate them for continuous operation or intermittent use they will put these readings on the faceplate or in the specifications documentation.
The EU regulation is not concerned with any of this . Their statement is that the power assistance on a continuous basis must not exceed 250w.
Paul at em3ev is good to deal with and is a top chap, but bear in mind that if anything goes wrong he is on the other side of the planet and you could find yourself with a very long downtime...there are many reputable importers here in the UK and it would be far easier if anything goes awry to return your motor/battery to them...I personally, support our UK vendors and have not had a problem with warranties, returns or support from anyone I've bought from...Just my ha'pennies worth and I hope I never have to say I told you so
D
Deleted member 4366
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That's the bit you have wrong. The regulation is on "rated" maximum continuous power, not maximum continuous power.
The engineer does all the calculations and tests, so that he has a good idea about the motor's actual limits. He's then worried about reliability, so he builds a safety factor into his rating. He has to consider and end user that might be so ignorant that he tries to start the motor from a standstill on a steep hill, or a very heavy guy that wants to go up steep hills, in which case he will leave a considerable margin between the rating and the power or torque that the motor can handle if treated respectfully.
Bosch, Yamaha and Brose motors are running round about 20 amps at 36v. That's 800w from the battery. With 75% efficiency, that would be 600w of output power at the crank.
Paul at em3ev is good to deal with and is a top chap, but bear in mind that if anything goes wrong he is on the other side of the planet and you could find yourself with a very long downtime...there are many reputable importers here in the UK and it would be far easier if anything goes awry to return your motor/battery to them...I personally, support our UK vendors and have not had a problem with warranties, returns or support from anyone I've bought from...Just my ha'pennies worth and I hope I never have to say I told you so
Oh, believe me, I'd rather shop 'locally', but trying to get any consistent advice - or any advice at all, seems to be nigh-on impossible. No response from either of the two obvious places to buy mid-drive Bafangs.
Like I said, I'm seriously considering a move into this marketplace since it is clearly only going to grow. In my experience, the current providers just don't seem ready to do a professional job, certainly in terms of initial communication. My thoughts are that if it's proving fruitless now when I've got the money to spend, how cr@ppy will it be when/if I get problems down the line.
Wow, is it really that bad Johnny, Steve UK, seems to have found some decent vendors if he would like to share.
I did try a local firm to me, that mostly sells model cars and pit bikes etc, they were advertising the Bafang units on eBay, but not in the shop, they told me that there was no stock of the 250w 8fun CD units, and did seem taken aback that I had linked them with the eBay site, not rocket science really, although that was back in July, and they expected to have stock by November, but I have not been back since to find out, and to be fair I was not feeling the love from them!
I did try a local firm to me, that mostly sells model cars and pit bikes etc, they were advertising the Bafang units on eBay, but not in the shop, they told me that there was no stock of the 250w 8fun CD units, and did seem taken aback that I had linked them with the eBay site, not rocket science really, although that was back in July, and they expected to have stock by November, but I have not been back since to find out, and to be fair I was not feeling the love from them!
The 2014 uk consultive document did refer to rated power but that term did not make its way into the final document the latest version of which is October 2016.
I do agree with your calculation that with if the motor was drawing 20a at 36v it will be consuming 800w , but that is not what the regulation demands.
I would agree with you that the prudent designer will follow the steps you have outlined and that will inform his her thinking in selecting gearing and torque.
The Irish statute law SI 412\2005 which would mirror the EU directive reads as follows " cycles with pedal assistance which are equipped with an auxiliary electric motor having a maximum continuous rated power of 0.25kW of which the power is progressively reduced and finally cut off as the vehicle reaches a speed of 25km/hr, or sooner if the cyclist stops pedalling. "
I apologise but it is easier for me to access Irish law. Although this regulation dates from 2005 , it is to the best of my understanding the current lwgal position.
The 200 watt original power limit in the U.K. Was to let someone have the power equivalent assistance of a average fit man , with a speed limit that the nominal ave fit man could achieve. The pushing of limits by manufacturers means that the bbs01 can be set to 18 amps at 42 volts or just under 800 watts.
That is above the maximum continuous output of an elete athlete.
If you add in 150 watts from yourself you will climb hills like lance armstrong.
Using this much power will drain the battery fast but we are a little short on 20 mile 10% climbs in the uk.
OK RB...at the risk of putting any noses out of joint (and you lot drying my supply sources up lol)...I only buy my batteries from Jimmy at Inst Intl (aka BGA reworking) as his build quality is second to none, he certainly knows his onions (as you will learn if you ever get one of his physics lectures
) and in the 2 times we've had a problem with his batteries (and we've had many) he's honoured his warranty and fixed them for free, he's even upgraded them with pure copper inter-connects (both of the broken batteries were used on DH bikes that take some massive hits/abuse/mud/etc and had split in half)...now here's the real "I don't want to upset anyone" bit...I've sourced my motors from Darren at Brighton eBikes (a member on here and top chap) and Eclipse Bikes in Gateshead, Darren is a dream to work with and a fellow eMTBer, but Eclipse can be slow to respond to emails and that can put people off. However, Eclipse deliver within the week if you order on the www, are consistently cheaper than any supplier I have found in the UK and their current stock are the latest BBSxxB with "improved" internals.***Sits back and awaits flaming
***Thanks for sharing Steve, I am new to all this ebike stuff, but was aware of Eclipse, although the last time I looked at there website the 250w Bafang 8fun CD was listed as out of stock.
Why is this such a cottage industry, even more so regards batteries, it does not give a regular punter like me any confidence to buy.
You mention the latest BBSxxB, I guess you mean the ones with 8 mosfets instead of 6 or whatever it is.
Darren at Brighton Ebikes seems like a good call, but is there no one in Manchester supplying Bafang motors and batteries kit.
You obviously know your stuff, and have real life experience of builds, I may have to give you a call if that is possible, I can do the build myself, so may just want to pick your brains.
Why is this such a cottage industry, even more so regards batteries, it does not give a regular punter like me any confidence to buy.
You mention the latest BBSxxB, I guess you mean the ones with 8 mosfets instead of 6 or whatever it is.
Darren at Brighton Ebikes seems like a good call, but is there no one in Manchester supplying Bafang motors and batteries kit.
You obviously know your stuff, and have real life experience of builds, I may have to give you a call if that is possible, I can do the build myself, so may just want to pick your brains.
...as have Eclipse and they are the latest BBSxxB http://www.eclipsebikes.com/bafang-8fun-bbs01-drive-250w-motor-p-1102.html
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