Cylindrical Lipo Batteries (12v)

[Richard Hill]

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I knew of the Vivax but I've not seen a picture as good as that before. Thanks that helps me to understand how they did it. The thing I find interesting at the moment is the way they handle the bevel gearing. Its a bespoke bottom bracket I still don't understand how they managed to sort out the issue or when power is not being applied and how the motor allows for free pedalling.

@Frankenstein I really appreciate that insight into the world of electric motors - I didn't realise it was pretty much spec out the demands and then go get it created.

The diameter of the test bike that I want to use is 24 mm - so the eton motor I chose fits with 1mm spare each side.

Looking at the tech specs for the motor that I got on here

And using this -:

• Power in Watts ~= kg.m torque x RPM

The tech spec of the motor is -:

• ET-PGM22A,
• 12V 84rpm 3kg.cm

As an approximation - I think this motor can produce -:

Power In Watts = 0.3 * 80 = 24 watts

Hmmm quite low really - and I agree probably an experienced cyclist like me would notice that but not all users would. I think this motor needs to be in the range of 75-100 WATTS to start to become more useful.

Going to contact the manufacturer and see what they can help with.

 

[Richard Hill]

The bottom bracket is coming out of the test bike at the weekend and I will be doing some calculations on what I think can be physically supported in there then.

 

[KCvale]

Curtain raiser ! Lol - i guess it is in a way. I don't need much power for what I want to achieve I just want to 'notice' that I am being assisted a little bit.
If you think that motor is a poor choice - how about you suggest one???

Sure, this electric bicycle kit From SickBikeParts http://sickbikeparts.com/electric-shifter-kit-shiftelectrikit-3000w/ will work just dandy.

The electric part connects to your pedal part to the motor so can use the pedals while you ride, or not ;-}

 

[Frankenstein]

Sure, this electric bicycle kit From SickBikeParts http://sickbikeparts.com/electric-shifter-kit-shiftelectrikit-3000w/ will work just dandy.

The electric part connects to your pedal part to the motor so can use the pedals while you ride, or not ;-}

Honestly would have been my first suggestion if he didn't seem adamant about putting it inside the bike, this would probably my the only way I'd go if I bought an electric motor for a bike, jackshaft spoiled me.

I knew of the Vivax but I've not seen a picture as good as that before. Thanks that helps me to understand how they did it. The thing I find interesting at the moment is the way they handle the bevel gearing. Its a bespoke bottom bracket I still don't understand how they managed to sort out the issue or when power is not being applied and how the motor allows for free pedalling.

There is probably a one way bearing within the gear on the bottom bracket shaft, in most cases you can Google the patent number and find a detailed image an engineer provided for said patent. Better than pulling apart your toys too!

 

[bakaneko]

There are also the rear hub geared and gearless motors for simplicity sakes. It seems like he just needs a little power. The gearless hub is cheapest but has a cogging effect where the magnets cause some freewheeling resistance while the geared hub reduces this. But, if he gets a 250W gearless I don't think the cogging will be that bad. There are 12V cylindrical lipo batteries but they are rare and expensive, as people mentioned most use 18650 cells grouped to provide the right voltage and capacity.

Besides, SickBikeParts there are also other more branded mid drive electric motor manufacturers. But, SBP do provide the best value for the buck in terms of power. Mid drive is generally more expensive and requires more setup time and tools. However, they freewheel (no resistance), higher efficiency in terms of gearing and drive gear, and have higher torque (efficiency) than other electric motors.

I am planning on building a "different" type of ebike and am going for the cheap 500W rear gearless hub motor ($135). Ideally, I would like to have a 500W Bafang, Yamaha, or Bosch mid drive with a kick ass carbon fiber fat bike but... that isnt really necessary as a proof of concept.

Also, 3000W is way over the legal limit for an eBike. Not that anyone might care if you are actually pedalling but if you are going 45 mph+ on an eBike and get stopped by the police or get in an accident then it might cause some problems. 750W is the federal legal limit and there are additional classifcations beyond that depending on your state. Enjoy the ride!

 

[FurryOnTheInside]

There are also the rear hub geared and gearless motors for simplicity sakes. It seems like he just needs a little power. The gearless hub is cheapest but has a cogging effect where the magnets cause some freewheeling resistance while the geared hub reduces this. But, if he gets a 250W gearless I don't think the cogging will be that bad. There are 12V cylindrical lipo batteries but they are rare and expensive, as people mentioned most use 18650 cells grouped to provide the right voltage and capacity.

Besides, SickBikeParts there are also other more branded mid drive electric motor manufacturers. But, SBP do provide the best value for the buck in terms of power. Mid drive is generally more expensive and requires more setup time and tools. However, they freewheel (no resistance), higher efficiency in terms of gearing and drive gear, and have higher torque (efficiency) than other electric motors.

I am planning on building a "different" type of ebike and am going for the cheap 500W rear gearless hub motor ($135). Ideally, I would like to have a 500W Bafang, Yamaha, or Bosch mid drive with a kick ass carbon fiber fat bike but... that isnt really necessary as a proof of concept.

Also, 3000W is way over the legal limit for an eBike. Not that anyone might care if you are actually pedalling but if you are going 45 mph+ on an eBike and get stopped by the police or get in an accident then it might cause some problems. 750W is the federal legal limit and there are additional classifcations beyond that depending on your state. Enjoy the ride!

My understanding (and I'm a total newbie at this stage) is that 3000W is the theoretical maximum that the motor can consume. The actual power supply from the controller should be lower to protect the motor, and then you still have to protect the controller by not running it at its theoretical maximum output either. If you put 833W into the 3000W motor, using a 1000W controller, you'll still only produce 750W and this should be sustainable on long hills, and not overheat and shorten the life of the components.

 

[bakaneko]

My understanding (and I'm a total newbie at this stage) is that 3000W is the theoretical maximum that the motor can consume. The actual power supply from the controller should be lower to protect the motor, and then you still have to protect the controller by not running it at its theoretical maximum output either. If you put 833W into the 3000W motor, using a 1000W controller, you'll still only produce 750W and this should be sustainable on long hills, and not overheat and shorten the life of the components.

Yeah, I don't think a cop can actually check this on the street. Okay, I just read the SBP listing a bit more closely and it said the power can be controller limited for legal street use. I still think that legal technicalities of this is shady. Yes, a 750W motor can produce more than 750W but I think if you go with the federal law and manufacturers definition of rated motor power you will be in the clear in case of a legal battle. The 3000W limited motor on the other case I am not so sure. Just about 2-3 months ago if you recall, there was some yahoo, who was obviously involved with an accident with a gas bike, was fishing around here trying to determine if the gas engine was over the limit for a legal case. I mean you can't tell the judge "yes it can produce 10HP but no I keep the throttle at below 4HP at all times; I promise..."

 

[FurryOnTheInside]

Yeah, I don't think a cop can actually check this on the street. Okay, I just read the SBP listing a bit more closely and it said the power can be controller limited for legal street use. I still think that legal technicalities of this is shady. Yes, a 750W motor can produce more than 750W but I think if you go with the federal law and manufacturers definition of rated motor power you will be in the clear in case of a legal battle. The 3000W limited motor on the other case I am not so sure. Just about 2-3 months ago if you recall, there was some yahoo, who was obviously involved with an accident with a gas bike, was fishing around here trying to determine if the gas engine was over the limit for a legal case. I mean you can't tell the judge "yes it can produce 10HP but no I keep the throttle at below 4HP at all times; I promise..."

The law is an ass, as usual. Anyway I'm going to over spec the motor and the controller so it can produce the legal limit without burning itself out, melting wires etc, as I have been reading that this is the only practical way.
I'm still reading up on it since I really don't know about electronics, but so far I'm planning to use a cheap so called "1000W" geared front hub kit with a SBP thumb throttle and a 36v battery pack, oh and the 2-stroke "for off road use only, officer".

 

[Frankenstein]

The law is an ass, as usual. Anyway I'm going to over spec the motor and the controller so it can produce the legal limit without burning itself out, melting wires etc, as I have been reading that this is the only practical way.
I'm still reading up on it since I really don't know about electronics, but so far I'm planning to use a cheap so called "1000W" geared front hub kit with a SBP thumb throttle and a 36v battery pack, oh and the 2-stroke "for off road use only, officer".

Long as the engine is cool to the touch when he pulls you over he's got nothing to say, at least in America that would be so.

 

[FurryOnTheInside]

Long as the engine is cool to the touch when he pulls you over he's got nothing to say, at least in America that would be so.

Over here the engine mustn't be connected to a wheel, or mustn't be a complete engine. Engine parts are fine, they're not technically an engine, so I pull the boot off the plug until I get to my traffic free route.
I think once I have my air box and side covers it won't matter anyway.