Left Drive Rear Hub Sprocket Dilemmas

[FarthingPenny]

Thanks for simulator link, but what 500W (1hp) motor should I be simulating? With 2 chain stages can get about 20:1 stepup of 84 rpm=1650rpm at 5 mph design point on 20" front wheel. Friend said telephone 48v is about highest can go for safety to reduce resistive losses. Motor diameter less than 85mm 3.25" and target weight 2kg

 

[FarthingPenny]

Photo mockup of first stage. So if just duplicate need motor of 1 hp/500w at 2000rpm. Can anyone suggest one please?

 

[FarthingPenny]

Here is a further mockup with the drive strut and the keyed/cottered crossaxle to the driven of the second stage. This will be triangulated above the chain shown to the top of the left fork. I don't cycle near children and dogs usually attack the pedals so I am hoping these parts are not too exposed. I hope to take the actual (Farthing Penny) bike out of service over the weekend to fit to it actually, and define better the space available below its bucket for the motor.

 

[FarthingPenny]

Here is a first fit to the actual bike. Tape roll is max motor diam 90mm. 52T chainwheel shown clears front fork ok but is a bit big for motor center. More like to be 46 teeth closer to free-wheeled mounted 44 teeth. On stand drove intermediate rpm to 2000 (4x design) and no shaking from eccentricity of cotter pin or problems apparent with chain running at actually upper stage max..

 

[FarthingPenny]

I was lucky to find Volcano Electric on Alibaba and they were very responsive on my motor spec. However their controller is 140x100mm (x62 deep) which seems unsuitable for a bike, with just a near full potentiometer for a throttle. Should I be looking for a controller made for a bicycle?

 

[amberwolf]

Here is a first fit to the actual bike.

My first thought seeing that picture was a memory of Naeem's bike here:

A Very Very Low Cost Electric Bike from Pakistan

Dear All, Many Regards! From my childhood i thougt of making a big electric toy with a very big motor and a very big battery cell so i will be able to ride it my self. i had the habit of breaking my toys and modifying it. so i would say that it was my childhood dream. With the...

endless-sphere.com

However their controller is 140x100mm (x62 deep) which seems unsuitable for a bike, with just a near full potentiometer for a throttle. Should I be looking for a controller made for a bicycle?

I'm not sure what you mean.
What controller were you looking at from that company?

 

[FarthingPenny]

My first thought seeing that picture was a memory of Naeem's bike here:

A Very Very Low Cost Electric Bike from Pakistan

Dear All, Many Regards! From my childhood i thougt of making a big electric toy with a very big motor and a very big battery cell so i will be able to ride it my self. i had the habit of breaking my toys and modifying it. so i would say that it was my childhood dream. With the...

endless-sphere.com

I'm not sure what you mean.
What controller were you looking at from that company?

Thanks for link to Naeem; I can see the chainwheel with the cutoff crank and the small drive wheel as similiarities. Here is video of test of my drive. No load.AVI

The controller is big 1.5kg . Concerned about connections and weatherpoof plus exposed 48V terminals. Would rather have cooling fins on motor.

 

[amberwolf]

The controller is big 1.5kg . Concerned about connections and weatherpoof plus exposed 48V terminals.

The switch and pot could be replaced with a waterproof one if you need to. Mouser, digikey, etc., carry those. Or you can seal up the back of the switch and just get a silicone cap cover for it that's secured by whatever panel you mount it to. If you don't use the switch you can just wire straight in for whatever function/setting it would engage.

Waterproofing the pot would be harder; easier to install it into a waterproof box with a shaft seal, or replacing it with waterproof pot.

THe connector, if always unused, you could simply fill with a waterproofing compound that seals it off. If you use dielectric grease you could then just put a cap over it that keeps the grease in.

There are plenty of insulating caps out there for various sizes of bolt heads. If not on mouser/digikey, probably on mcmaster-carr and similar places.

most of these things can also be had from the usual ebay, ali* amazon etc but harder to be sure that what you're buying is what you're getting or that you even picked the right one in the first place.

Would rather have cooling fins on motor.

What does the motor look like? Mightve missed it but didn't see it in any of hte images/etc.

 

[FarthingPenny]

The switch and pot could be replaced with a waterproof one if you need to. Mouser, digikey, etc., carry those. Or you can seal up the back of the switch and just get a silicone cap cover for it that's secured by whatever panel you mount it to. If you don't use the switch you can just wire straight in for whatever function/setting it would engage.

Waterproofing the pot would be harder; easier to install it into a waterproof box with a shaft seal, or replacing it with waterproof pot.

THe connector, if always unused, you could simply fill with a waterproofing compound that seals it off. If you use dielectric grease you could then just put a cap over it that keeps the grease in.

There are plenty of insulating caps out there for various sizes of bolt heads. If not on mouser/digikey, probably on mcmaster-carr and similar places.

most of these things can also be had from the usual ebay, ali* amazon etc but harder to be sure that what you're buying is what you're getting or that you even picked the right one in the first place.




What does the motor look like? Mightve missed it but didn't see it in any of hte images/etc.

Thanks alot for all the advice on the controls. I really would like a lever throttle say 0-90 pot rather than full 360.
Here is the motor drawing, the cross-section is constrained by where in the existing bike it has to fit into. The motor design point is 2 N-m at 2280 rpm corresponding to 1 in 5 grade at 5mph as gear ratio is 27

 

[Chalo]

Thanks alot for all the advice on the controls. I really would like a lever throttle say 0-90 pot rather than full 360.
Here is the motor drawing, the cross-section is constrained by where in the existing bike it has to fit into. The motor design point is 2 N-m at 2280 rpm corresponding to 1 in 5 grade at 5mph as gear ratio is 27View attachment 365132

That looks like a servomotor. I wonder how efficient it is? It might have more waste heat to dispose of than if it were a traction motor.

 

[amberwolf]

The good news is that it has lots of flat surfaces that you can mount standard heatsinks to if you need them. If you do, look up lapping and CPU overclocking methods for good ways to make them fit properly for best heat transfer. And make sure you use fin types and directions that best disturb the airflow around them to force more heat transfer from them to the air; more surface ara is usually better.

If you're running the motor within it's spec'd limits (whatever those are, not on the drawing and no brand/model is listed***) and in the required environmental conditions, then you won't need the heatsinks.

If you push it past it's limits, load it outside it's spec'd RPM range for that load, or don't provide whatever environmentall conditoins it's specs are tested in, then you might need heatsinks just to keep it from burning up.



***Dunno if this really applies here, but there's a lot of people that come here for help with whatever system, but never give the full details of what they have or are doing, who we could have helped much more efficiently if we'd had that info; potentially warning them away from things that wouldn't do the job they need or would make it harder / more expensive, guiding them towards better-suited items/processes, etc. Some are very secretive about things for no apparent reason, and some just don't think of posting anything until it's directly asked for, and some just don't post it then either. Sometimes we can't even answer their questions because of the missing info (which we may not even know is missing).

 

[amberwolf]

Thanks alot for all the advice on the controls. I really would like a lever throttle say 0-90 pot rather than full 360.
Here is the motor drawing, the cross-section is constrained by where in the existing bike it has to fit into. The motor design point is 2 N-m at 2280 rpm corresponding to 1 in 5 grade at 5mph as gear ratio is 27View attachment 365132

I don't know what the quote is supposed to "say"? (since it's the same as what was already in the post it quotes)?