Coaxial-BB-Jackshaft Middrive with TGY Rotomax 80cc Build

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The weight of a KU93 sensorless controller is only 420g or 0.42kg. This is half of an 18FET Looks like I found a treasure here I just have to lift

this way one can get around all of those low induction controllers issue without ANY hassle. btw here is the calc for the N6353, power needed is only 2kw at the rear wheel comes close to whiplash's drive. I just reject using a tiny 12T on the wheel that wont last minutes on full throttle. The smallest one I trust is 16T.

 

[Whiplash]

The smallest I have run is a 11T which actually lasted a while. Probably a few hundred miles so I'm hoping I can get maybe 500+ from the 12T you just have to make sure the derailleur is adjusted to wrap the sprocket as much as possible. This was also a VERY cheap cluster. I'm sure a nice one would last longer or possibly I can harden the small sprocket??

 

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Dont know what cassette you've got. The 12-36 i can get from my local shop are the more expensive ones, guess they are already hardened. But even with a better sprocket the chain wont survive much longer. Used only one 11T yet, it lasted about 100km at 600watt input. Didn't change the cassette, used the next sprocket (12T) EDIT: 13T. Lasted about 500km. Barely used the other gears. after that i got a 9speed sram hub, which ran fine for 2000km, then I sold it for a good price. Could not stand more than 500watts, My dealer told me.

My sprockets and chain should at least last 5000km. Everything else is unreliable and goes into trash

Guess your 12T will survive much longer since it will barely be used.

 

[jpgey]

Ok here is the simplified version
This circuit operates as follows -
The ignition key enables the circuit, a button is held in to turn it on. A dash light illuminates when the system is on. Key off turns it off again.

Hello, it seems the "push to start button" does nothing !
You should have a ON contact somewhere instead of NO.
I will try to find you a better circuit

 

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hey jpgey,

i dont get that either, but the general function of this circuit is clear. There has to be a positive connection to get the left relais to pull on.

The dual motor option is a great thing IMO. I saw that greenbike sells 45amp/48V sensorless controllers.
http://www.aliexpress.com/store/pro...shless-speed-controller/313864_497637202.html
Since they are the largest ones yet I bought two of them, just to know how good they are. Maybe i'll switch to the 1.4 rotomax when I got it running well. Btw, does anyone have interest in an 80cc or a 150cc rotomax? I would give them away for a special price for ES members, especially European members, since they have too much power for my purpose.

 

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I just talked to Leo from GREENTIME. He says he can supply all of their controllers as sensorless, even the 36Fet versions. Now just ordered a single 15Fet one with 45amps limit, we'll see how it does on the N6354 and the 80cc turnegy when it arrives.

 

[Whiplash]

Dont know what cassette you've got. The 12-36 i can get from my local shop are the more expensive ones, guess they are already hardened. But even with a better sprocket the chain wont survive much longer. Used only one 11T yet, it lasted about 100km at 600watt input. Didn't change the cassette, used the next sprocket (12T) EDIT: 13T. Lasted about 500km. Barely used the other gears. after that i got a 9speed sram hub, which ran fine for 2000km, then I sold it for a good price. Could not stand more than 500watts, My dealer told me.

My sprockets and chain should at least last 5000km. Everything else is unreliable and goes into trash

Guess your 12T will survive much longer since it will barely be used.

That's kind of the idea, most people will cruise along around 25-30 happily so I think I'll be OK since that will be more like a 14t or so. The 12t will only be for speed runs..

 

[briangv99]

I just talked to Leo from GREENTIME. He says he can supply all of their controllers as sensorless, even the 36Fet versions. Now just ordered a single 15Fet one with 45amps limit, we'll see how it does on the N6354 and the 80cc turnegy when it arrives.

It will be interesting to see if the e-rpm limit is higher than the Xiechang sensorless controllers. The Xiechang (Infineon) controller were only capable of about 20,000 e-rpm (a bit over 2,000rpm tested with a Turnigy c80100) before it would cut out.

 

[Miles]

Judged solely by the given spec., this one looks to be quite good: http://www.hobbyking.com/hobbyking/store/__17987__Turnigy_RotoMax_50cc_Size_Brushless_Outrunner_Motor.html

 

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The N6354 isn't the perfect motor for rpm around 4000. with 14p, Pole count is just too low. The rotomax 1.4 would be much better, looks like 20poles.

Guess the new 15fet will work fine on the star terminated 116kv N6354. It will fail with 200kv delta. Even at star this would be a lot more than 20k rpm. Next time i do some test on the N6354 i'll meausure e-rpm to get some results here. Thx for intervention, brian

@miles: i do think it's very hard to get this one cooled properly. Stator is 50mm and will produce about 400W heat. That wont work i guess

 

[mr.electric]

Awesome build project. I have a ku 123 if you need it pm me and I'll give it to you. I might also have an extra ku 93.

 

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soldered the 6 wires. Made some pics to show how it works. You need soldering flux to get the magnet wire soldered after burning the insulation at the ends. Tip the ends into the soldering flux and heat it, without burning flames. Get rid of the ash this way. After repeating that a few time on each end, you can solder them.

 

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I'm back on single speed, single reduction. I read about using multiple controllers for one motor, separating the stator into coil groups. Just need to rewind it a little special.

The original 80cc has 193, I would want to get half of that. The motor comes with 8turn winds. If we now separate the motor into 2 coil groups, each one would have 12coils and 16turns for 193KV or 32Turns for half of that. This way this motor could be driven by 2 sensorless ebike controllers. This will lower induction, the controllers will need some beef up and lebowski snubbers to work properly i guess.

My 150cc motor will arrive on tuesday. Hope I can post some pictures then, the 80cc wont look much different.

Edit: Looks like these motors have 24poles. This can only be divided into two or four coil groups.

 

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Short update: Leo is still soldering my controller. Dont know why I paid him extra get it shipped to me fast

I can catch my 150cc rotomax from the post office, but since I lack of time i'll sell it immediately without measure inductance, sorry guys I will at least measure distances and take some pics for you. I'll measure inductance on the 80cc, maybe we can somehow extrapolate it for the 150cc.

Played around a bit with my Arduino. Had to experience that hall current sensors are quite expensive. I'll stick to the common ACS709 PCB module, since 10 bucks is the most I want to spend for a current sensor. I can only measure up to 75amps, but that's a good start.
Got hooked up my LCD, hope I can get the speedo function done tonight. This is just a teaser pic

 

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I found this page: https://github.com/jenkie/Arduino-Pedelec-Controller

Seems to be I'm not the only one who tries making such a device. I will use the "Forumscontroller" as a base and beef it up for at least 75amps battery current and a true torque control throttle mode and a phase current limit.

Maybe someone who owns an RC controller could help to write a library for an RC-ESC throttle interface?

I'm sorry to tell you that most discussion will continue in German, but i'll keep you guys up to date on this.

Since this has not much to do with my original topic, i'll start a new one on this.

 

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I started a new topic about the Arduino Project here: http://endless-sphere.com/forums/viewtopic.php?f=2&t=47124

 

[fechter]

Allegro makes hall effect current sensors that go up to 200A
http://www.digikey.com/product-detail/en/ACS758ECB-200B-PFF-T/620-1323-ND/2042748
$7 US ea.

Their datasheet also shows a trick where you put two of them in parallel, but only use one to measure. This doubles the range.

 

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pics of the turnigy rotomax 150cc

radial bearing size: 30 x 17 x 7 mm (there are two of them in a row)

 

[circuit]

This looks nice.
Any info on inductance and no-load power?

 

[crossbreak]

sry, I have no osci and signal generator here :? I can measure no load current tonight if you want.

looks like the rotor was balanced dynamically.

 

[Whiplash]

Wow! That's quite a motor there! 150kv is almost manageable as well! Should be a beast! Now if you can fit internal hall sensors so we can use a bike controller it would be awesome!

 

[circuit]

sry, I have no osci and signal generator here :? I can measure no load current tonight if you want.

Would it be possible to bring it to a friend or someone else, like an electronics shop, who have the inductance meter? It is probably the most important parameter of these BLDC motors.
Also you could do two important tests:
1. hook it up to a controller and measure no-load phase current. You can do it with fast AC current meter. Also DC current (known voltage) battery would be interesting to see.
2. disconnect the motor from everything. Find a fast second motor (preferably 10k RPM or more) and hook it's shaft to this one. Run it at 100% speed, record input power and RPM. Then run it at 75% and record. Also 50% and 25%. After this test, run the other motor with no load (disconnect the shaft from rotomax). Run it at all four speeds (match the RPM) and record power consumption. Then subtract no-load power from loaded (with rotomax) and you will get a simple mechanical (and passive electrical, if any) losses.

These figures would be extremely interesting to see.

 

[bearing]

Nice motor. How thick are the laminations?

EDIT: From the other thread, 0.2mm?
http://endless-sphere.com/forums/viewtopic.php?p=631589#p631589

 

[fechter]

That's a really impressive looking motor

I like the thrust bearing. It won't have much loading in a bike application. It could possibly even be removed to reduce drag.

It looks like it should have pretty good cooling but some kind of fan or impeller would help the air flow. The slots in the rotor will sort of work like that.

I'll be interested to see how it performs.

 

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the 80cc motor arrived finally

some update on the controller i'll use:
>> 24x IRFB3077
>> sensorless operation
>> 115A phase current limit
>> 85A battery current limit
>> fast throttle response
>> 37V LVC

battery:
12s6p zippy 15c 44.4V*30ah=1.3kWh