High power RC motor and drive unit production

Pm Matt, aka recumpence, aka reduction ninja, aka e-smile guru, aka the one who started this whole mess of going really really fast with really really small motors.
 
I'm not sure if you guys know this, but if you really wanted to see the exact wattage going into your wheel, you could look into a Powertap hub. The most basic model is pretty cheap at around $600 on ebay. (They are designed to monitor a cyclists power output). Just build up your super beefy wheel around the hub.

The key would be mounting your drive sprocket on the bike hub side (where the typical bike cassette of gears normally goes).

If you do that, which is actually quite simple (if you don't need a traditional pedal drivetrain), then you can monitor the exact power outputs of your system. Powertap CPU display shows wattage up to only 1999watts, but when you download the data, there is no limit, you see everything. This is also a great way to track your accelerations/speed. Although, the powertap isn't the most precise instrument since it only takes data at 1.26 second intervals.

One other concern might be the freewheel hub - will it withstand 10,000+ watts? It might, but I can only guarantee about 2000, haha.
 
veloman said:
I'm not sure if you guys know this, but if you really wanted to see the exact wattage going into your wheel, you could look into a Powertap hub.
Also: http://www.ibikesports.com/products_isport.html Simpler to incorporate and cheaper but probably a bit less accurate than the PowerTap, especially at higher speeds.
 
The PowerTap hub was wonderful when testing my Cyclone setup. (PowerTap Watts) / (Watt's Up Watts) * 100% = system efficiency (excluding rolling resistance). It's also great for optimizing gearing. The new PowerTap hubs also have ANT+ Sport signals for use with other devices. You can buy chips with antennae that can read that. If you put that on a board with current/voltage sensors, you can get constant efficiency readings. And that is far better than Wh/mile for comparing e-bikes.

If I ever get the money for an RC setup, I will be sure to test it on my PowerTap wheel.
 
voicecoils said:
recumpence said:
swbluto said:
You can go with basic components and get in for about $700 for a basic motor, simple drive, and more basic ESC. $1000 for those components will get you some nice stuff. $1500 will take you to the stars! :wink:

For perspective, $1.5k is not outragous when serious MTB'ers spend $4k+ on downhill rigs and dirt bikes easily get to $10k+ before upgrades.


I work in the bicycle industry, & now days $4k does not get much of a downhill bike...$6-8K (in OZ)... my new carbon MTB race bike (on order) is RRP $10.5k. :twisted: we are all plugging for ya!!!... 15kw RC drive... now that's for me... :D

I am sure to give in to RC temptation, after I see Grinhill's RC setup... he rides past my house on his way to work... :mrgreen:

K
 
wow what a read.. well its 4am here and I just finished trudging my way through all 70 odd pages of posts :shock:

At lest now I'm all up to date and more confident than ever that this setup is perfect for me.

Any chance on an update Matt? Have you sold many more drives in the last few months or just been using them on your own projects?

Also did you ever end up selling that single prototype mount you made back in May?

My apologies if this topic has moved on to a new thread.

-Capo
 
I have sold (If I am figuering correctly) 26 or 27 drive units. It may be more.

Anyway, I have frame mount kits in stock. The come in 1.5 inch ID, 2 inch, and 2.5 inch ID.

Matt
 
Capo_au said:
wow what a read.. well its 4am here and I just finished trudging my way through all 70 odd pages of posts :shock:

You deserve a medal for that effort. :D
 
Hi,

Do anyone knows of some RC controllers to which I could connect a torque sensor signal ?

I am quite interested in Marc's unit but I would like a power assist system like the one you find on the Panasonic Motors : the harder you pedal
the more power you get !

thanks a lot
Patrice , from France
 
patsagn said:
Hi,

Do anyone knows of some RC controllers to which I could connect a torque sensor signal ?

I am quite interested in Marc's unit but I would like a power assist system like the one you find on the Panasonic Motors : the harder you pedal
the more power you get !

thanks a lot
Patrice , from France

Do you have the torque sensor on the bike where you can connect the signal? If so, it may be possible to use the RC throttelizer as a current-controlled throttle using the torque sensor signal (Assuming the torque sensor is a three-wire, 5V power supply, signal-out type of device) - the harder you pedal, the more current it supplies. If you want to have a hand throttle in addition to the torque sensor signal, then I think something could be arranged.
 
Hello,

I don't have a crank torque sensor right now but I saw some that are for sell. I might buy one if I can figure out how to arrange all these components alltogether and if I get the chance to put my hands on this beautiful peace of work Marc has done.

You product seems the perfect tool to use . Do you have any feed back from users ?
Would that work with a Castle Phoenix HV-110 controller/ astrofilght engine ?
an finally what about price ?

cheers
Patrice
 
Hi,

Do you have the torque sensor on the bike where you can connect the signal? If so, it may be possible to use the RC throttelizer as a current-controlled throttle using the torque sensor signal (Assuming the torque sensor is a three-wire, 5V power supply, signal-out type of device) - the harder you pedal, the more current it supplies. If you want to have a hand throttle in addition to the torque sensor signal, then I think something could be arranged.

I don't have a crank torque sensor right now but I saw some that are for sell. I might buy one if I can figure out how to arrange all these components all together and if I get the chance to put my hands on this beautiful peace of work Marc has done.

He means you can purchase one of these:
http://www.endless-sphere.com/forums/viewtopic.php?f=9&t=11877&p=180070#p180070
Up for the offering is an RC throttle enhancing converter! It's basically a small electronic device that takes a regular e-bike/e-scooter/e-motorcycle throttle, hall or a pot throttle, and allows it to control the ESC while also adding features on such as temperature protection, current limiting, "current controlled mode", a customizable current ramp, LVC (Low voltage cutout for the battery), an e-brake connection and it also has usb ports that can be used to attach additional devices such as a SD data logger and/or a CA-like display (Currently being developed) and many more possible additions in the future. It's also programmable so you can customize pretty much all of the features above. It also comes with additional LOW ESR capacitors to prevent nasty voltage spikes on the power wires that's been known to kill ESCs - I'm setting the rating to 63V so you can get as much capacitance as you can, but you can get 100V ones on special request. So, how is this device better than the servo tester route? You don't have to buy a separate BEC, a servo tester and extra capacitors and do a lot of work. With this, you also get fairly important temperature protection which can prevent your $100-250 controller from blowing, your expensive motor from melting and/or your battery's life being cut, customizable throttle ramp, a programmable Low Voltage Cutoff, and a better current-based throttle control and the ability to program it just the way you want it.
 
patsagn said:
Hello,

I don't have a crank torque sensor right now but I saw some that are for sell. I might buy one if I can figure out how to arrange all these components alltogether and if I get the chance to put my hands on this beautiful peace of work Marc has done.

You product seems the perfect tool to use . Do you have any feed back from users ?
Would that work with a Castle Phoenix HV-110 controller/ astrofilght engine ?
an finally what about price ?

cheers
Patrice

Yes, according to feedback, it works well with the Castle Phoenix HV controllers and the Turnigy controllers and those controllers seem to work well with the Astroflight motors. There seemed to be issues with cheap-quality throttles, but those have been solved.

We'd be more than welcome to custom make one to suit a torque sensor. Just throw us some torque sensors that you're considering and we'll look at the data-sheets or whatever is available and design accordingly. It'll be programmable so that it can be adjusted to suit how it really is in real life. When a torque sensor is chosen, It might be best to develop it for the sensor in hand if it's fairly complex and the technical info isn't available.

And, for you, I wouldn't charge any more than the normal price. The 120 amp version is 94.99, and shipping to France is 12.99. While it's true that special customization usually costs a little extra, expanding the product's ability to be integrated with torque sensors would widen its potential uses and appeal.
 
Thanks for all the information,

I will think about it.. I am still hesitating between building a bike from scratch or buying one (raleigh dover 40) as I need to get rid of my old petite reine..
It is also difficult to get answers from Marc, he must be too busy building units !

Patrice
 
Miles said:
The torque constant is inversely proportional to the velocity constant.

There's a maximum constant torque output, which is the same for all the winding configurations. As you say, the amps needed to get this will vary with Kv/Kt/number of turns.

6t needs 63 amps
7t needs 54 amps
8t needs 47 amps
10t needs 38 amps

Power is torque times velocity (motor speed).

Miles,

I know this is lag time behind your post but... I get the 3210 10t wants 38 amps for 375 in oz of output power and remains > 90% efficient however, the true maximum power of an Astro (unknown efficiency) is actually 600 in oz of power which with a Kt (Torque Constant) of 10 means 50 amps for the 500 in oz.

The thing I don't understand (or do understand but it seems wrong to me), am I correct that the faster the RC motor spins... the higher the end power will be (each reduction step becomes a multiplier for the output torque?)...

Example:

12S LiPo 4P 20AH 20C - 4.15v per cell works out to: 44.4 nominal voltage.
At 44.4 volts the motor RPM (assuming minimum 90% efficiency) would be: 5394.6 RPM
Astro specs list the best amps on this motor at 17 which with the Kt (if accurate) is wrong... 17A would give you 170 Kt but the same docs claim best motor efficiency at 93% and 190 in oz, that would be 19A right?
They claim the figure of 375 in oz above 90% efficiency so... Using the Astro provided Kt: 375 / 10 = 37.5 A, close enough to the 38A you specified.

Power at this 12S nominal point is now a mere: 1665 watts (well below my 10t tower pro).

Astro also claims a peak of 500 in ounces of torque for up to 60 seconds... this is interesting, 500 / Kt = 50A. Now we have a max nominal power of 50 * 44.4 = 2220

Assuming further that the quote on the 3210 being most efficient 93% at 190 in oz, but that 17A is the best for the 10t 3210 then... 190 / 17 = 11.1765 in oz per amp would be the correct Kt.
That shifts everything just a bit, now 375 in oz is actually requiring only 33.55254 amps.

If I were to gear down 92t / 13t for a 7.07 : 1 then my output RPM to the rear wheel on a nominal 44v pack would be: 763 RPM for a top speed of 45 mph on a 20" wheel.

I am planning to use either thuds 2 speed transmission or my own 2 speed hack, either will provide a 2:1 reduction increasing the final maximum reduction to 14.14 : 1 and providing rear wheel RPM of 381.5 RPM for a top speed of 22.7 mph (it will range from 25 to 20 as the pack discharges).

Now if I have all my ducks in a row (if the above makes reasonable sense, I did round up and down a bit) then I calculate the following:

[Maximum Continuous Torque Output]
12S - 44.4v @ 33.6A = 375 in oz * 14.14 for 5302.5 in oz (27.617 ft lbs) torque in low gear with 22.7 mph top end
12S - 44.4v @ 33.6A = 376 in oz * 7.07 for 2651 in oz (13.807 ft lbs) torque in low gear with 45 mph top end

Assuming accurate Kt (I'll contact bob for clarification) of 11.1765 and the rated 500 in oz maximum for 60 seconds, then 500 / 11.1765 = 44.736724377041113049702500782893 A (call it 45 A) - again not much but 5A difference can mean alot in range).

[Maximum Burstable Torque Output @ 60 Seconds]
12S - 44.4v @ 45A = 500 in oz * 14.14 for 7070 in oz (36.82 ft lbs) torque in low gear with 22.7 mph top end
12S - 44.4v @ 45A = 500 in oz * 7.07 for 3535 in oz ( 18.41 ft lbs) torque in high gear with 45 mph top end

If power = torque * velocity (motor RPM) which makes sense since smaller motors develop their output by spinning faster, then how do the above numbers change if I move from a 12S (44v nominal) to a 15S (55.5v nominal). The motor would spin at 135 * 55.5 = 7492.5 * . 90 = 6743.25 RPM. Assuming the same kT and output for 375 in oz (nominal max with 90% efficiency), then... to acheive the same output at the rear wheel (RPM) reduction must be increased... 92t / 10t = 9.02: 1 so 9.02:1 High Gear and 18.04:1 Low gear reductions:

Nevermind, I get it...

6743.25 / 9.02 = 747.59 RPM for 44.49 mph top speed (same as before) and a maximum torque of: 375 * 9.02 = 3382.5 in oz (17.617 ft lbs torque) in high gear (increase of 3.81 ft lbs of torque in low gear, ie power)
6743.25 / 18.04 = 373.80 RPM for 22.24 mph top speed (same as before) and a maximum continuous torque output of: 375 * 18.04 = 6765 in oz ( 35.23 ft lbs) torque in low gear (increase of 7.613 ft lbs of output torque)

So if I went from 10t to a 6t I would in theory, roughly double the output torque without changing the input current or voltage from 10t on a 10S (37v nom) pack. The wattage/hp would remain the same (more or less) but the torque would increase by multiples of the reduction?

Do I finally have this right?

Thanks in advance,
Mike
 
Mike,

I'll check over your working later.

It's a lot easier to see the relationships if you work in SI units...........

Torque in Nm
Shaft speed in radians per second

Kt = Torque constant in Nm/A
Ke = Back EMF constant in V/(rad/sec)

Ke = Kt = 1/Kv
 
I do not have the math to give you exact numbers, however, if you double the RPM, then gear down an extra 50%, you will double your torque. This will not double your power per watt (you cannot create power from nowhere). But, it will double your torque (static pressure). This will give you a greater hit (accelleration), though not a true doubling of power.

Have I confused you yet?

I really need to learn the math related to this...........

Matt
 
mwkeefer said:
12S LiPo 4P 20AH 20C - 4.15v per cell works out to: 44.4 nominal voltage.
At 44.4 volts the motor RPM (assuming minimum 90% efficiency) would be: 5394.6 RPM
Astro specs list the best amps on this motor at 17 which with the Kt (if accurate) is wrong... 17A would give you 170 Kt but the same docs claim best motor efficiency at 93% and 190 in oz, that would be 19A right?

Mike,

The Kv and Kt values quoted for the 10t are consistent with each other and the max. cont. torque current. I guess the problem is with the peak efficiency torque quoted... The other values in the Best Amps column are consistent with a peak efficiency torque of 170 oz-in.

There are rather a lot of typos/inconsistencies on the Astro website.....
 
I am working on V3 drive units today, tomorrow, and through the rest of the week. All Astro groupd buy customers will be receiving these new drives.

I will have pics for you by week's end. The V3 drives are simply beautiful (if I do say so myself)! :D

They have outboard motor shaft bearing supports, are lighter, have a much more organic look, and are overall better quality. All components are individually shimmed for smooth operation and there are no more worries about motor mount screws galling the aluminum face plate.

Oh, I am also working on a cool add-on for my drives. I am not saying what it is just yet. :wink:

Matt
 
come out from behind the curtain!!!!
me, Dorothy, scarecrow, cowardly lion and tinman want to see the V3 :twisted:


D
 
Ahh, yes my son. You shall see, you shall see! :)

We made one particular part incorrectly (10 of them) Monday. So, we are recutting those tomorrow or I would show you pictures.

Basically I am pushing to advance the original drive design as far as I can without completely redesigning it. The adjustable layout and modular design works so well, I do not want to change it. However, there have been some niggling minor issues that needed correcting. Nothing major, just little annoyances. I have spent some time making sure the new components are backward compatible so all previous drives can use spare parts from the new drives as well as the "New" component I am making.

You shall see, my son, you shall see. :wink:

Matt
 
Woot backward compatible!!! put me down for one of everything that fits my drive Matt !!! seriously...any chance
for gold anodising on the parts too please?

KiM
 
Gold Anodising??!! :twisted: Now your speaking my language, I don't know why people go through all the trouble to anodize something black when gold IS the new black. :lol:

Hmmmmm, Outboard bearing: check
Backward compatible: check
Sleeker design: check
Dual motor mount plate: check

What else could there be? Chain/ belt tensioner? I know!!! It's a belt chain guard/ enclosure, Isn't it?? :mrgreen:
 
hope its a tensioner, built on a single motor arm :mrgreen:

D
 
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