Finalized! - Longboard Alien Drive Systems - single C6374

[666yeti666]

well the motor looks the same I can see.

However what worries me is that it could happen again. I opened the motor (removed rotor) and did see that there's no mechanical fixture or whatsoever that could prevent it from rotating on the mounting plate.
Usually there is some kind of groove in the rotor and the mounting plate in which a (threaded) pin is located, since with these kind of forces that is necessary.

Here's an example of how it should be properly done (scorpion motor) :


And as you can see here, that has not been done with giantsharks motor .....


And some other good examples :

 

[666yeti666]

During the wait for the response about the motor I decided to increase the size of the grubscrews of the motorpinion since I think that 3mm is not proportional to the size of the 10mm motoraxle (my RC helicopter motors have 8mm axles and they are using 4mm grubscrews as well).
So decided to drill two extra holes for the new m4 grubscrews and cutted the thread.

(for your information : use a drill which is 80% of the thread you want to use, so for m4, use a 0.8x4mm = 3.2mm drill for the hole. oh and don't forget the oil for cutting the thread, can safe you a thread cutter... )
In the 2nd and 3rd picture you can see the significant difference in size between m3 and m4.
Despite the use of the slot in the axle, this gives me a better feeling to hold the pinion and to prevent it sliding axial across the motor-axle.

ps. contacted Bruno and he confirmed quickly that the custom black alien motors do have a mechanical coupling pin between rotor and mounting plate!

 

[666yeti666]

short update:
contacted supplier (giantshark.co.uk) regarding defect motor and he admitted that there could be a manufacturing fault. Sent it back to them, expect a refund...

New motor ordered at Bruno from alienpowersystems.com . He replied quickly on all my questions and sent out the motor also very quickly.
It is also a C6374 but with 170 kv (200kv is not standard available). It is a custom motor with better bearings , mechanical pin between stator and mounting plate. This motor : http://alienpowersystem.com/shop/63mm/alien-6374-outrunner-brushless-motor-170kv-3200wa/

Due to the lower kv (170 instead of 200), my top end speed will be around 26km/h. After a speed test on my bike to work the average speed is between 18 and 20km/h and I think this is a very nice cruising speed on a longboard. 26km/h is to my opinion already quite fast for a non-experienced-skateboarder like me
So I expect to be happy with that speed...

regards
Sebastien

 

[666yeti666]

new motor dropped in today.
Differences with the old motor :
- pin inserted for mechanical coupling the stator with the mounting plate
- windings are made with thicker wire
- winding looks more decent
- pre-fabricated 3mm keyway (which is unfortunately too short for the key...)
- mounting plate more open, so better cooling





now to find the time to mount it .....

 

[BShady]

regarding the anti-spark, why dont you make it on the xt90 key thing (emergency plug) so its always there and when you put the key in it doesn't spark, and leave the other connection in? similar qu why not run the resistor in series?

 

[torqueboards]

regarding the anti-spark, why dont you make it on the xt90 key thing (emergency plug) so its always there and when you put the key in it doesn't spark, and leave the other connection in? similar qu why not run the resistor in series?

Yeah, I was thinking the same thing. Have the antispark between the xt90 on/off plug. That way when you connect it w/ the opposite xt90 it will eat the spark. Leave that part disconnected when connecting the battery and there should be no spark. The spark should only come when it makes a complete connection. That way you can keep the batteries plugged in.

 

[Nikimce]

On that note, does anyone have a wiring diagram that uses the xt90 as a plug/switch? I'm trying To figure out a better method for wiring everything up.

 

[torqueboards]

On that note, does anyone have a wiring diagram that uses the xt90 as a plug/switch? I'm trying To figure out a better method for wiring everything up.

What are you having an issue with? The ground wire would break into a XT90 and would go around the other end. Then you plug in the other side of the xt90 it basically just completes the connection kind of harder to explain. Will try and post when I add it to my new builds.

 

[666yeti666]

I'm not sure what you guys are meaning, but remember that the antispark resistor (6.8 Ohm/5W) should ONLY in the current path, just before connecting the batteryplug, in order to charge the (low ESR) capacitors of the ESC. When this plug is in, the resistor should not be in the current path anymore as it will be fused by overheat.

Other news that I have from the C6374-200kv motor from Graham of giantshark-uk.com is that I have sent the motor back to the UK for investigation. Since I have used it in a skateboard it is NOT under warranty and as such he will not help me further ... so very dissapointed about this behaviour. I could get the motor back when I pay for the shiping cost again. So people are warned NOT to buy this motor at that shop ...

regards
Sebastien

 

[beetbocks]

hmm-that's disappointing..skateboard,large scale rc car -whats the difference? maybe you should have kept quiet about the application.. :wink:

 

[made_in_the_alps_legacy]

... maybe you should have kept quiet about the application.. :wink:

true

... So people are warned NOT to buy this motor at that shop ...

did you get some more detailled infos from them on this issue ? if there is a specific batch or delivery dates of potentially affected motors ?
(I am afraid I have some of these motors too... this being said, that would the first time I would receive non conform products from them, and I deal with them since years for motors, ESC, and chargers...)

 

[666yeti666]

your are both true about mentioning the application, but I'm an honest guy and expected the same from Graham of giantshark-uk.com but it appeared to be different ....
I hoped for sharing cost or something like this but there is no support at all. To make it even worse I can get the motor back when I pay for the shipping cost, which I already did for 2 times :-(
I'm in the RC hobby for more then 15years but this kind of bad service I have never had before, it's really unbelievable.

Also I didn't get any more information from him unfortunately. I feel like a powerless customer, crying in the desert ...

When I receive the motor back, I will try to repair it and make a mechanical fixture.

regards
Sebastien

 

[beetbocks]

yes i agree honesty is the best policy.but have you actually run the motor on the board,under load? if not then i do not see the warranty problem..

 

[666yeti666]

yes I did a test under load, I sat on the board and did some very small rides through the livingroom, due to the rainy weather. So it must be during that only moment that the rotor shifted ...

By the way, I did a test in the same way with the new motor last week and tested the brake of the ESC; programmed it to 50% and well, what can I say, it didn't brake at all .... so I have strong doubts if an "electronic" brake will even work.
What is happening inside the ESC is that the transistors intermittently shorten the windings of the motor, and so creating a force that will stop the motor from rotating (that is the funny noise that you hear while braking). The current can become considerably due to the fact that the back EMF and as such the induced voltage of the motor is proportional to its speed and for instance when riding down from a bridge with high speed and then longer braking could maybe even destroy the ESC or let it go into protection I can imagine.

What are the experiences of others with the brake of the ESC ?? Maybe Bruno can tell something more about this ?
(I recently saw a post of a guy using disc brakes on his front wheels !)

regards
Sebastien

 

[made_in_the_alps_legacy]

The faster u go, the better the brake works. Don't know how fast u can ride in ur living room, but if you try it from full speed, you would feel the braking force decreasing to no braking at all when reaching low speed, even if you are 100% braking all the time from full speed
(It is typical of electromagnetic braking)

 

[torqueboards]

The faster u go, the better the brake works. Don't know how fast u can ride in ur living room, but if you try it from full speed, you would feel the braking force decreasing to no braking at all when reaching low speed, even if you are 100% braking all the time from full speed
(It is typical of electromagnetic braking)

I don't know about the faster you go the better the brake works. I highly doubt that. The brakes do work extremely well though. I'd say 15mph to stop is perfect and they work as intended. However, braking from 20mph+ to a stop - you need a certain distance to stop on point (I wouldn't consider this better). It's also not definitely smoother the faster you go as it is a belt driven pulley. Disc brakes - yes I could imagine they are equal at faster speeds.

Why do you say the brakes are better at faster speeds?

 

[beetbocks]

I can confirm the brakes will work fine at higher speeds , Of at least 10mph , the ESC needs a back signal to know how much reverse force to give ,the speed in your living room would have been only 2-3mph ..so the brake force would have be proportionate .. The force gets greater the faster you go ..

 

[made_in_the_alps_legacy]

Why do you say the brakes are better at faster speeds?

well... don't ask me, ask Mister Lorentz, he is the one who said

where he could not resist to relate force, électric charge, and magnetic field : you could eventually notice that he included velocity in his law.

side note : it seems obvious to me that we are prone to spread discutable ideas, some might be wrong and I believe this is the core of a discussion forum to clarify, but sometimes, it's helpfull to firstly doubt about ourselves before doubting about the others. :wink:

 

[666yeti666]

Hi All,
good news, yesterday I could ride my board for the very first test ride !
And what can I say, it drove very good. I must say I’m not used to ride on a longboard and that’s something you can see on the video ....

http://youtu.be/f-9Pc1bEnpE

I noticed the following :
- motor makes quite some noise
- braking makes quite some noise
- braking is working so-so, could be better
- brake-force increases with increasing speed (as was noted before)
- alien drivetrain works flawless
- riding away from a deadstop is working very good due to softstart of ESC, no stuttering
- acceleration is very good
- motor has lots of torque, throttle changes during driving is brutal
- maximum current draw is only 32A while max power equals about 740W

For next time I will try to make some GPS readouts about speed and distance.
Also I will show a plot of the Eagletree datalogger.

regards
Sebastien

 

[beetbocks]

That looks great.
- the motors are quite noisy but I like that noise,especially when you give it some hard throttle..
- the brake is not perfect and is only really meant as an assistance,what percentage brake have you set the ESC to?
- the brake noise seems very unusual,none of my boards make the noise...some thing maybe not quire right..?
- on the plus side it does make a great horn,as you mentioned..as I have often thought I need a horn as nobody ever hears you coming..I just whistle loud..
Overall though I think it was a successful first run.. Well done..

 

[made_in_the_alps_legacy]

- motor has lots of torque, throttle changes during driving is brutal
- maximum current draw is only 32A while max power equals about 740W

That's nice, so your battery can deliver something like 5550W, your ESC about at least 3330W, and your motor is given for 3200W,
... but only 740W used : you have a x4 "reliability factor" and a potential to save weight :wink:

edit : watched the vid' - brake makes the same noise as mine

 

[superpef]

Nice Work, have fun with it!
Yes, your brake sounds weird, you might want to investigate..

 

[beetbocks]

I have spoke with Bruno about the noise and he's so busy at the minute that's not being able to see much on the forum but he thinks it may be the timing on your ESC..on the Alien ESC you can change the motor timing in steps of 1 ,as we are not sure what ESC your using you may need to experiment with different settings..
hope this helps..

 

[666yeti666]

thanks to all for the nice comments

@Richard,
aha thanks for the remark , let me check it.
I'm using the Hobbywing Ezrun 150A which is used a lot on this forum. From the top of my head the braking force is set to 25%, but I'll check the settings and post them here.

@made-in-the-alps,
indeed, the drivetrain is totally overpowered, and I think I could get good performance with a smaller motor and ESC as well.
But the challenge with a smaller motor is the kv. Usually the kv will increase with decreasing motor size which I could compensate with lower voltage (4s lipo) but then the current would increase which leads to higher losses... mmmm .....
Other solution is to choose a higher gear ratio (currently is only 15/32).
A custom wound motor (small with low kv) is also very nice but quite expensive ...

For the ESC I could choose a smaller one, although mechanically it is quite small already.
It did not run hot, so maybe I will try to get rid of the fan.
Main reason for this ESC is the good braking options , the cell count, uptill 6s lipo and the price.

regards
Sebastien

 

[666yeti666]

@made-in the-alps:
by the way, those powers you have mentioned are only peak powers, so they do not say much about power in "real life conditions"

The motor is indeed spec'd as 3200W. But suppose that this can be delivered with an efficiency of 90% (which is already high) then this would mean that the power losses in the motor would be 320W !
If this really could be the case, then the temperature of the copper windings would become soo high that the isolation would burn and the ESC would go into current protection or will be blown. Also the temperature of the neodym magnets will become too high resulting in magnetic loss, and the motor as such will become useless...

So I'm not taken the spec'd power ratings too serious

regards
Sebastien