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[Reaper]

Finally!  I am on my way.  I just bought this brushless motor here: http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=130309475183

Now I need a brushless controller.  As I understand it, there are only two options.  There's a Sevcon PMAC, and a Kelly controller.  Are there any other candidates?  All of these brushless controllers seem to get into the 500 dollar range rather quickly.  I'd like to keep it around $300.  There's Electricvehiclesusa.com selling a 400 amp controller for 318 dollars, but they say that it will take 4 weeks to ship.  That's quite a bit of time to be expected to wait.

Also I am told to get higher amperage, even if the motor only draws 300amps peak to go for 400 amps.  Is this really necessary?

Thanks for any advice.

[Bogan]

um, i would expect to pay quite a bit for a brushless controller. 4 weeks shipping sounds like ages, see if you can find somebody else who stocks the same item and ask them to match the price. Dont know if you need to go for a 400amp controller as the motor can only handle 300amps for a very short period of time (only rated at 100 continuous), getting a controler that can do more current will greatly reduce heat buildup in said controller, but for short burst this shouldnt be an issue.

[Reaper]

Thanks for the response.

It looks like I'll be hitting up ebay again then... I was hoping to get a brushless controller for at best 350 dollars.  Someone told me that the Kelly controllers wouldn't even work.  Does that mean that Sevcon has the monopoly on this?

I hope not.  That controller could run me as high as 500 dollars.

[frodus]

there's just not that many people out there making BLDC controllers. Kelly does make one but its noisy and Kelly is severely overrated (expect to get half or less of the amps it says its got).... Sevcon makes that one and it tops out at 84V... so those are your two options for BLDC. BLDC is more expensive because its got 6 channels of FET's inside (1 positive/1 negative for each phase of the motor), not 1 like brushed controllers.

Long and short, unless you get used, you'll be spending more than $350 for a controller.

[Bogan]

also the power of bldc seems to be significantly less than that of brushed dc motors, but whether you need lots depends on your project of course

[frodus]

Exactly.... best to match motor and controller....

what kind of motor is it "ebay" is blocked at work...

[Reaper]

It doesn't seem to be too bad of a motor.  It's a Mars brushless.  I've done a little web research on this.  From what I can tell, the torque on the motors varies... but not enough for me to be super concerned about the power.  I think it's something along these lines...


Etek-R 1.0 in-lbs/amp

Etek-RT 1.2 in-lbs/amp

Mars Brushless 1.0 or 1.12 in-lbs/amp  (I've seen both figures on two different websites) 


As far as I can tell, the Mars brushless seems to be right in the ballpark.  I've seen people be concerned with the power but it looks like that's because they were using the Sevcon Millipak PMAC controller which is only rated for 250amps.  The Mars brushless, like all of the other Etek motors seem to be able to handle 300amps peak so the controller deprives the user of an additional 50 amps that should be used for speed.  I've emailed electricmotorsport and asked them whether or not I should get a Sevcon and they said "only if you are o.k. with 40mph."

No.

I'd be o.k. with 45-50 mph, but I am about the size of an American football player so I am kind of a big guy.  I can be realistic if it cuts top speed by 5-10 mph.   

I've also emailed Kelly controllers, whom I'll probably end up going with and they said that their controllers now operate in either a sinusoidal or trapazoidal pattern, meaning that it should be free of all of the problems with noise and inefficiency that were mentioned before as the motor expects a sinusoidal pattern and the controller generated only a trap one.  They even advertise the motor saying "this motor (my brushless one) works well with KBL 48301 and KBL 72301"

On paper it would seem like everything pans out.  In reality... we'll see.  I am going to order in about a week and a half.  So far, the Kelly controller is BY FAR in the lead versus the Sevcon, having more amperage, a little cheaper, and having a one month refundable, 1 year warranty.

I've changed the scope of my project some, and basically just want this to be a commuter bike between work and home which is about 13 miles.

Thanks every for your responses!

[frodus]

I'd get double the amps that you THINK you need... if you want a 400A controller, get an 800A....

the kelly controllers overrate their controllers and the current nosedives as soon as you start going.... not sure why... but they don't hold the current.... I wouldn't mess around... get something that'l give you enough current to get up and go. 600A might be enough.... but even then, those mars can't do 300A continuous for very long, or if they do, they need sufficient cooling.

[Reaper]

That's good advice Frodus... but unfortunately the budget does not allow.  The brushless controller that I am ordering now is going to set me back nearly 500 dollars at 300 amps.

The 500-600 amp controllers start looking like 1000 dollars REALLY QUICKLY.  I can't do that, this project has already been something of a money pit.  By the end of this month I want the lion's share of the spending done and by the end of next... hopefully something that I can put out on the street.

And if Kelly's controller doesn't work then I have to get irate with them until they either replace it with something that does work, or I give them it back and go with something else.     

This project was worth it if nothing else other than the learning experience.  I'll probably build another one down the line, but next time with additional kick ass... 72 volts probably, MUCH BIGGER controller... and not brushless.

I want this one done.  Even if it can't do much more than carry me around the block.  My other bike an ICE bike is toast and I don't really care at this point of the bike ends up flawed somehow and only has the power to take me to the grocery store and back.

I'll take it.

I've got to seal off this money pit before I get addicted and it sets me back lots more dough.