PDA

View Full Version : Stupid question #2



Lionstrike
15 September 2010, 0947
I am sure that I am not the first person to ask this question so forgive me for being a dumbass, but for a first time ecomodder, should I go brushed... or brushless with the motor type?

My first failed attempt at a conversion used a Sevcon PMAC controller and a Mars brushless motor. The Sevcon controller was such a pain to work with I think that I would have rather set myself on fire and sprint down the street screaming. I have been hearing good things about the Kelly controllers lately though.

The reason for my asking is that I've been doing some more reading up lately on evalbum and some other websites and it looks like some folks are only getting something in the neighborhood of 700 hours out of the brushes on their Etek style motors. That sounded pretty FAIL to me. If I have to replace a full set of brushes once a month, that doesn't make it competitive with a standard gasoline motorcycle to me. Plus, I am not a fan of high maintenance vehicles, and the low maintenance aspect of EVs is another huge selling point for me.

Other folks have claimed that brushes in motors are good for 10,000 hours. Wait a sec... which is it? 700 miles or 10,000 hours? I am getting drastically differing information here.

So, which do you prefer folks? Brushed or brushless?

Thanks.

frodus
15 September 2010, 0959
wow, only 700hours? I guess it depends on how much current you're drawing, the more amps at higher RPM, the faster the wear.


I prefer brushless, but I'm using an Induction motor (not BLDC, but brushless nonetheless). Haven't ridden it yet, but a friend has the same motor and its running strong, easy to mess with and program. It may be more expensive, but no brush wear, little to no maintenance (only bearings), regen capability if you want it, higher efficiency....

I did like my Series wound brushed DC motor though, that thing was a beast! I could really pull hard with that motor.

I think the brushes in the series wound are a little more stout, and can handle more amps at higher RPM. Mine was a 4-brush motor, but they have some that have 2 brushes per position for 2x the ampacity. The motors are huge though.

Lionstrike
15 September 2010, 1011
Thanks for the reply man.

So brushless sounds like a pretty good idea...

But I'll be damned if I have to deal with that Sevcon controller again. I HATED that thing. I'd do a Kelly 48301 first.

It was this guy who said that he burned out his brushes at 700 miles: http://www.evalbum.com/1291

I have about a 25 mile a day commute so that would be pretty rough on total hours. At that rate, 28 commutes to work would probably require another full set of brushes. That's probably between 1.5-3 months of actual use. That's not so good.

It looks like brushes are commonly sold in packs of 8. and are about 100 bucks to replace a full set. YIKES! So if I burn through them every two months that's about $50/month. Add that up with the cost of electric charging and it looks like I am out of some loot.

I might have to take this project back to the drawing board. If the brushes don't last the thousands of hours that some people claim, then it isn't cost efficient to do a brushed type conversion.

EVcycle
15 September 2010, 1015
There are several good points on both sides.

I have several Brushed PM motors and one brush less series motor. Each one works well for its application. I have still not see the higher efficiency part proven between the two (Ed sticks his tongue out at Frodus) . I like the brushed for the smaller good low end torque motorcycle applications.

In the Zap car they started with brushed and changed over to the series for the heavier vehicle.

What does all this mean?

IMHO, Pick the motor that will fit your goals for the project. Brush packs are normally easy to replace and I have not had to replace one yet that wore out.

Lionstrike
15 September 2010, 1032
Haha.... brushed versus brushless...... EV FIGHT!!!!!

FIGHT! FIGHT! FIGHT! FIGHT!

(Sorry I couldn't miss the opportunity to turn this into high school all over again).

I think that picking a motor that best suits my application is the operative idea here. Very good point Sir. So then, here's what I envision and am trying to achieve:

Basically I am looking to just learn about conversions and create something that works, but ultimately I would like to create a totally functional vehicle that could serve as a daily commuter.

As a commuter vehicle, it would have to be able to handle my 25 mile/day commute and achieve close to a 50 mph top speed that could be maintained for about 2-3 minutes.

I got a 48v contactor, reversing contactor (which I actually might keep for the hell of it) and a curtis 24-48 volt 275 amp controller on ebay for about $80. I thought that was a pretty sweet deal and I had to bargain with the seller at length to get the price down to that point. It's got the diodes and resistors too.

Looks like all I need is a throttle (this is a motorcycle BTW in case I didn't mention it) and a motor. I'll probably get a Magura 0-5k throttle this month which just leaves...

The motor. I've played absolute hell trying to figure out which motor I should get. That's probably because I am an EV infant lol.

I thought about an 0909 like I said... but top speed maybe 40mph. No bad... could do a little better though. Then I thought about a 0709 etek-rt. Better.... and leaves me room to move up if I need to. Then I thought about the brand NEW ones that just came out that support 200 amp continuous like these monsters here:

http://www.evdrives.com/motors_overview_conversions.html

Double brush set though... double the cost of brush replacement.

Then I told myself maybe I should go brushless.... but then I get 48v tops, and GOD HELP ME IF I HAVE TO DEAL WITH ANOTHER SEVCON CONTROLLER!!

It also renders the absolute steal that I got on ebay... useless.

So I guess I am a little lost. I'll do brushed if I can get a year or so's worth of life out of it before I have to replace the brushes (you said that yours are still going... how many hours are on them again?). Or I'll go brushless if I can get the price down to a reasonable level and it doesn't make me want to set myself on fire with the configuration.

Any suggestions there?

frodus
15 September 2010, 1117
Haha, Ed, you're funny :) Let me rephrase.

As far as efficiency, ACIM and BLDC can be built to have a very high Eff. Those Agni's are pretty damned Eff. The things that count against brushed, are the brushes themselves, frictional losses from brushes, resistance of brushes, arcing. My Series wound was crap for efficiency, barely above 80%. I'm looking to be 5-10% higher (from the motor curves) in eff. That was my comparison.


I agree though, design within the constraints. If you need high power/low weight/low cost, then brushed PM motors might be the ticket. If you need long life, good efficiency, sealed design, high RPM, then maybe Brushless would suite better. just because its brushless doesn't mean 48V tops. The mars motor can be used at higher voltage, so can Marks Hubmotor.



I think that one guy with 700hours was doing something wrong. Wrong gearing and too many amps maybe? Maybe shoot him an email, because I'm pretty sure Ed and others using the Etek have gotten far more hours on their brushes.

Lionstrike
15 September 2010, 1130
Good advice...

I wouldn't mind performing a kind of yearly maintenance on the vehicle... brushes... brakes... that kind of thing. But if it's going to be like 100 dollars every other month, it's not saving me much money.

It does look like the guy in evalbum semi-abused the motor. Doin' a bit of drag racing if I understand correctly. I could see that as being rough on the brushes, sure.

I do need a fairly beefy motor though for sure. I am a bigger guy (avid powerlifter) so I am about the size of an NFL lineman, and 300lbs. I think on the other forum someone recommended and Etek-RT for me, perhaps it was Juiced himself.

Another thing that I think that I might be misunderstanding is this concept of hours and miles... some folks seem to be posting their results in terms of hours... others miles.

If I understand correctly, (and please correct me if I am wrong) is that the Etek motors are good for about 1000 hours rather than miles. At that point however, they'd be nearly completely destroyed.

1000 hours however... is workable. I commute just about 1 hour a day so 1000 commutes means that I could probably get a couple of years out of those brushes.

I could deal with that. :D

ZoomSmith
15 September 2010, 1154
I'm with Ed on this one. Don't get hung up on the brushed vs. brushless.

Given the extra bulk you have to haul, I would advise against the ETEK's. Look at Advanced DC or D&D motors. Not quite as efficient, but it will have the power you need.

Lionstrike
15 September 2010, 1200
No love for the Etek motor? I thought it was one of the more commonly used and more favored motors out there.

I thought that D&D motors were Sepex... I don't think that it'd work with my Curtis controller.

I did some (admittedly probably poor) research into advanced DC motors. They seemed to be real expensive and their HP stats seemed to be lower than an ETEK.

Juiced told me that an RT gets him and his wife to 50mph when they are riding together and the two of them weigh about as much as me. Is the RT not a valid option?

EVcycle
15 September 2010, 1221
Fight Fight Fight.....Naaaaaaaaaaaaaaaa

Etek is a valid but..... (Loads of opinions here)

I think we chatted about this, but for the record. (and to refresh my memory) What is the total weight of the purposed bike?
Batteries, motor, empty bike now, rider....etc. Actually out bike will do 62 with both of us and almost 70 with just me on it. Weigh is an issue. With more weight, more current draw....

Lionstrike
15 September 2010, 1235
Ahhhh I see. Juiced is EVcycle. EVcycle is Juiced.

I am on the same page that you are... I am trying to keep this thing as light as possible. I think my rolling chassis is only about 150lbs or so.

Rolling chassis ~ 150
Motor ~ 40
Batteries (lots being lead acid... let's say ~ 175 starting at 48v)

Probably looking at close to 400lbs by the time I am done with the thing. Me on it? More like 700 lbs total.

I'd settle for 50mph.

So here's the plan... my other motorcycle (2006 Honda Shadow 600 VLX) is probably going to go to bed for the season in about a month and a half. Something bad happens right around this time...

I go stir crazy. If I am not riding a motorcycle I must wrench on one. If I can do neither, then I go INSANE and start climbing the walls.

It gets real bad in late December. The University that I work for closes for a full two weeks just before the new year. It's too cold to ride... and there's snow on the ground. This frequently gives me MOTORCYCLE MADNESS.

So this will be my winter project. The plan is to gather the parts now... wrench later.

I just want to make sure that I have the right parts... and if I could get it cheaply.. that'd be good. Not only do I work for the University, I also am a post grad student. And college courses = $$$$$$$$$$$$$$$$$$$$$$

That's why money is such a factor to me in choosing parts. My boss at work wants to see me taking more classes. And even with my discount, a single class (with books and stuff) is easily 600-700 bucks.

Doesn't leave a whole lot of money for EV parts :(

ZoomSmith
15 September 2010, 1314
D&D has Series Wound as well. You are correct D&D and ADC are more expensive.
Sure RT will work, but is it the best for your application? If cost is the deciding factor, then the RT has the upper hand.
Just my opinion.... As with any opinion, take it with a grain of salt. ;-)

EVcycle
15 September 2010, 1323
Juiced is EVcycle. EVcycle was Juiced. :):)

IMHO An Etek will work but it depends on how much you want to accelerate. Remember our bike is running LifePo4 Cells and is lighter than your ultimate bike. ETEK does have a new motor that will handle it better. Also Ditto on Zoomie/Frodus comments!

frodus
15 September 2010, 1331
I think a higher HP motor with more thermal mass might be a better choice, others may disagree. Especially if there is lots of stopping and starting. The D&D and ADC motors like the K91 (which is what I had in my first setup) are pretty good, they're about 35-40hp max, but at 96V. You'll probably have a hard time getting 50mph and have decent acceleration with 48V and 700lbs worth of load to accelerate.

I'd start rethinking things a little, you might need either higher voltage or a higher current controller. 275A at 48V won't really push you that hard, and I'm skeptical that it'd even reach 50mph. If it does, it'l take a while to get there.

Most motorcycle conversions I've seen are in the higher voltage ranges (72-96V), and much higher current (450A and above).

I think you can get a D&D or ADC for less than $700 if you look around.

And with either motor, if you get one now, and use the curtis, it'l work as you tweak things, and if you want to upgrade to a larger controller, you can.



I'd just stick with brushed, but size the motor accordingly, and anticipate a controller/battery pack upgrade.

teddillard
15 September 2010, 1340
The Cycle formerly known as Juiced? :p

Brushed or brushless... brushed or brushless... hmmm. taptaptap. I say.......

YES!

EVcycle
15 September 2010, 1343
What coast are you on? I think D&D is East coast and ADC is West coast. Is that right Travis?


Shipping is another consideration if you end up looking at apples to apples motors.

teddillard
15 September 2010, 1348
Windows crash more than apples to apples motors.

...where the hell is that nurse with my meds?

frodus
15 September 2010, 1400
yeah, but i think you can get some decent pricing through a distributor, they might not wanna sell direct. I got better pricing through a distributor than I did via ADC, although i already had a motor.

Lionstrike
15 September 2010, 1547
Thermal mass? Geez folks, tryin' to build an electric motorcycle here not an atomic bomb. LOL The knowledge in this forum is seriously above my pay grade.

Cost is a huge factor (like I said... still taking post grad courses)... but I could always move up later. I am not building the final incarnation of this beast yet. Really I am hoping to hit something mid range with this first one... something to learn a little bit on, but something that could be made into something stronger later with a few hundred bucks. Perhaps a stronger controller and more batteries.

I am an East Coast native (Pennsylvania). I'll probably get parts through evdrives.com or cloudelectric. I've done a lot of searching and it just looks like those folks have the best prices around.

Thanks again everyone for all of the great advice.

EVcycle
15 September 2010, 1602
D&D Motors.
215 Park Ave. - Syracuse, NY 13204
Phone (315) 701-0635 - Fax (315) 701-0859

Lionstrike
15 September 2010, 1605
Geez, that's as much in gas as shipping is.

I think I might play ebay ninja and just wait for my opportunity to strike....