# BLDC motors at Currentevtech any good?



## corbin (Apr 6, 2010)

rwaudio said:


> I was just browsing and came across some new BLDC motors w/controller, that are water cooled, regen capable, 80kw for $5850. I didn't find anything about them on here already, does anyone know how these would compare to the usual Warp 9 and similar?
> 
> 80kw is closer to the peak power rating I'm looking for, torque is good, continuous power is 40kw which is good, regen capable etc. and the price isn't that crazy.
> 
> ...


Whoa, I'm curious too. If I didn't already have my Warp9, I'd probably go for this motor. This is the AC motor I was looking for, at the price I wanted to pay. I'm bummed I didn't see it two months ago, or know about it.

corbin


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## patrickza (Dec 28, 2009)

Didn't see your post when I started mine. It's also a motor I'm looking at, just not sure I want to be the first to buy one. Come on, pull the trigger, you know you want to


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## DIYguy (Sep 18, 2008)

says to contact [email protected].... dave kois perhaps??? of the old evcomponents??


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## rwaudio (May 22, 2008)

patrickza said:


> Didn't see your post when I started mine. It's also a motor I'm looking at, just not sure I want to be the first to buy one. Come on, pull the trigger, you know you want to


LOL I don't want to be the first either, so most likely I will end up with a Warp/Kostov motor. I wish I had the extra cash to take the risk, it could be a great combo.

It is Dave Kois, (I personally don't know anything about him or his history, but he has been great at answering questions and getting me info about the motor)

This is a bit of extra info he gave me for the motor:
At 288V

Torque
1000 RPM--238.75 Nm
2000 RPM-- 253 Nm
3000 RPM- 238.75 Nm
4000 RPM---191 Nm
5000 RPM--152.8 Nm


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## JRoque (Mar 9, 2010)

> dave kois perhaps??? of the old evcomponents??


Yes, it's Dave and he is part of the "good" side of EVComponents, not to be mistaken with Dr Evil Morrison.

I had asked Dave about that package and he said things like motor performance graphs are cut for each motor when it's sold so he doesn't have one just yet.

I'd be interested in finding out the dimensions of the controller itself. I have another vendor from China that offers a similar package and his controller is rather large and might be difficult to fit in my EV. He offered to work on redesigning the controller layout to make it smaller. 

JR


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## Bowser330 (Jun 15, 2008)

JRoque said:


> Yes, it's Dave and he is part of the "good" side of EVComponents, not to be mistaken with Dr Evil Morrison.
> 
> I had asked Dave about that package and he said things like motor performance graphs are cut for each motor when it's sold so he doesn't have one just yet.
> 
> ...


+1, I also read in a previous post that the 80kw setup could possibly do 100-120kw if used at the maximum voltage and not the nominal...

AC/BLDC will eventually surpass DC for the DIY Market, but it wont be anytime soon, not with the eVnetics and Netgain making controllers and motors that are capable of higher power for similar cost to the consumer...

80kw (107hp) for 5,850$

373kw (500hp) for 6,300$ (Soliton1[Race] + Warp11HV)


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## Pirape (Feb 26, 2009)

Bowser330 said:


> +1, I also read in a previous post that the 80kw setup could possibly do 100-120kw if used at the maximum voltage and not the nominal...
> 
> AC/BLDC will eventually surpass DC for the DIY Market, but it wont be anytime soon, not with the eVnetics and Netgain making controllers and motors that are capable of higher power for similar cost to the consumer...
> 
> ...


I am no expert but I used to race with brushed motors and in is in no way comparable to the performance of a Brushless motor of the same type

The brushless motors are much much more efficient. They are generating less heat, turns faster and doesn't use as much current. I forgot to mention that they require ZERO maintenance (no brushes)


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## tomofreno (Mar 3, 2009)

> Yes, it's Dave and he is part of the "good" side of EVComponents


 +2, and 40kW continuous is great! Try getting that out of a Warp9 without a lot of added cooling. I see that as the main advantage of BLDC motors - no current in the rotor, so far less heat to dissipate. Much easier to pull heat out of the field windings. But note it is 11" diameter - hard to fit in many cars.


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## rwaudio (May 22, 2008)

lowcarbon-idea said:


> Dear Gentlemen,
> I am Chris from lowcarbon-idea. It is very glad to take part in the BLDC traction system discussion here.
> BLDC motor is the popular trend of the EV conversion market. its advantage is the brushed or AC induction motor can not come up to.
> Our company offer the various BLDC drive system, if you intersted, please
> ...


Do you have a torque curve for the motor, based on the power output of the controller listed? The combo price seems really cheap (for an 80kw BLDC anyways), what kind of warranty do you offer? As well as customer support / install advise / trouble shooting? Are there any examples of EV's that use this motor/controller combo so we could get some real world feedback? It's hard to be the first person to jump into a new product like this without knowing more.


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## Kelmark (Oct 26, 2009)

I am also interested in this system.


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## Pirape (Feb 26, 2009)

Kelmark said:


> I am also interested in this system.


So am I, Lowcarbon-Idea's combo is very very interesting!!


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## Kelmark (Oct 26, 2009)

tomofreno said:


> +2, and 40kW continuous is great! Try getting that out of a Warp9 without a lot of added cooling. I see that as the main advantage of BLDC motors - no current in the rotor, so far less heat to dissipate. Much easier to pull heat out of the field windings. But note it is 11" diameter - hard to fit in many cars.


Tom or anyone,

The 80kw is a bit heavier than what I was looking for my project. On the other hand, the 40KW peak 20kw continues looks comparable with the HPEV AC-50. From looking at the numbers the system is the same weight, but has higher continues power rating and higher efficiency which is great. 

One thing I wasn't sure on was whether the BLDC 40kw "54hp" @288V (which could be bumped to 336v), was more powerful overall than the HPEV AC50 system? 

I was told, "the 110 ft lbs of torque drops of after about 3500 RPM" If this is true than this package might have a little more than the AC-50 for $500.00 less! What are your thoughts?

I found where the AC-50 was listed at 37kw and Tom stated at 115v he was getting around 49kw.


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## tomofreno (Mar 3, 2009)

> I was told, "the 110 ft lbs of torque drops of after about 3500 RPM" If this is true than this package might have a little more than the AC-50 for $500.00 less! What are your thoughts?


 If you examine the dyno data for the AC-50 given on several web sites that offer the motor for sale, it shows torque falling off at about 3000 rpm with a nominal 96V pack that sagged down to 85V at higher motor rpm. You can maintain max torque to higher rpm, and get higher shaft power, by using higher pack voltage. My nominal 115V pack should give max torque to about 3900 rpm, and max of about 67 HP. Also on the curve you will see the max torque is about 90 lb-ft, not 110. Bill at HPEVS also told me it is 90, lower than that of the AC31, so that they could maintain max torque to higher rpm. Look at the data. I don't know why some think that if you increase pack voltage you increase max torque. You don't, that is determined by the max current the controller can deliver. If you run the BLDC motor at higher voltage I expect you would also get more power from it. You might check with the supplier. The continous power rating of the BLDC is higher than that of the AC50, about 27 HP versus 15 HP. Although I think the 15 is conservative.


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## Kelmark (Oct 26, 2009)

tomofreno said:


> If you examine the dyno data for the AC-50 given on several web sites that offer the motor for sale, it shows torque falling off at about 3000 rpm with a nominal 96V pack that sagged down to 85V at higher motor rpm. You can maintain max torque to higher rpm, and get higher shaft power, by using higher pack voltage. My nominal 115V pack should give max torque to about 3900 rpm, and max of about 67 HP. Also on the curve you will see the max torque is about 90 lb-ft, not 110. Bill at HPEVS also told me it is 90, lower than that of the AC31, so that they could maintain max torque to higher rpm. Look at the data. I don't know why some think that if you increase pack voltage you increase max torque. You don't, that is determined by the max current the controller can deliver. If you run the BLDC motor at higher voltage I expect you would also get more power from it. You might check with the supplier. The continous power rating of the BLDC is higher than that of the AC50, about 27 HP versus 15 HP. Although I think the 15 is conservative.


Tom,

The 110 ft lbs of torque out to 3500 rpm is the info Dave gave me for the BLDC 40KW system at 288V. If ran at 336V I am guessing that it could hold that 110 ft lbs out further similar to what you did with the AC-50.

I was comparing that to the 90 ft lbs. of the AC50. If this data is correct I would think the BLDC would provide slightly better acceleration. I thought I read somewhere that the AC50 was higher than 40kw though so that would conflict with my assumption.


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## JRoque (Mar 9, 2010)

Hi. Not to deviate too much from the excellent conversation here but, I'm a little apprehensive about going to higher voltage to run the BLDC package. 

Higher voltage runs more efficiently due to the drop in current. There's less heat, cables can be smaller, etc. But there are several issues with the higher count cells: 

- More connections means more losses - perhaps enough to invalidate the lower gauge cable gains
- Higher potential for arcing from loose connections
- Higher BMS cost and complexity, more difficult to maintain without a BMS.
- Lower Ah cells don't maintain proportional volume and weight as higher rated cells. A 100Ah isn't exactly half the volume and weight as a 200Ah cell.
- DC/DC converters and chargers are not always available above certain voltages (~350VDC).
- There are more cells to strap down and tuck away

The Curtis' 120V max is kinda lowish. But ~144V and 500A would do nicely while keeping the cell count low. 

What's others take on high/low voltage vs cell count?

JR


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## tomofreno (Mar 3, 2009)

> What's others take on high/low voltage vs cell count?


 Pretty much agree with what you said. Fewer cells certainly makes it easier to check them manually once in a while, and as you said fewer cells/connections/parts to fail. I'm biased toward simplicity though, and also because I have a lower voltage pack. It is appealing to run at high voltage and halve currents. Smaller cells are also easier to fit into irregularly shaped spaces, but then again it is hard to fit so many.


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## dtbaker (Jan 5, 2008)

I think the sweet spot for all the components seems to be either 120v or 144v when you balance cost, availability, and major component 'limits' off the shelf. seems like when you start going over 144v, so many things get WAY more expensive and hard to find.


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## JRoque (Mar 9, 2010)

Thanks Tom/Dan. Good to see we agree on that point. Anyone with a counter argument?

Chris from Low Carbon Idea: you do have specs for amperage output from the BLDC controllers at lower volt inputs, say 144VDC? You had mentioned the BLDC controller has a hard time keeping up with the rated amperage at lower voltages but it'd be great to know the exact number at 144V.

JR


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## Kelmark (Oct 26, 2009)

JRoque said:


> Thanks Tom/Dan. Good to see we agree on that point. Anyone with a counter argument?
> 
> Chris from Low Carbon Idea: you do have specs for amperage output from the BLDC controllers at lower volt inputs, say 144VDC? You had mentioned the BLDC controller has a hard time keeping up with the rated amperage at lower voltages but it'd be great to know the exact number at 144V.
> 
> JR


 
I also think that if someone is looking for cost effective lower maintenance option lower voltage packs are the way to go. The trade off is you will not be able to get the motor eff of 95% and controller eff 97% with that route.

For my application I am looking for a smaller lighter pack that can handle 5C continues and peak 12C+ amps. To accomplish this they will be lightweight, low IR, high power prismatic cells. High efficiency is a priority with my goals though. This will add allot of cost and some complexity.

To eliminate some of the complexity I may have the packs w/BMS built professionally so the entire system is under warranty. Plug and play is a wonderful thought.


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## Kelmark (Oct 26, 2009)

JRoque said:


> More connections means more losses - perhaps enough to invalidate the lower gauge cable gains
> 
> What's others take on high/low voltage vs cell count?
> JR


I would have to disagree with this statement as each connection has a fixed resistance the affect it has is dependant on the amount of amps flowing through it.

So if you had a 288V system (90cells) drawing 250 A; 

And a 144V system (45cells) drawing 500 A the overall resistance should be equal for the same power output.

So you would still benefit from the reduced resistance in wires to controller and motor. In addition you would be able to achieve the 95% motor / 97% controller eff.


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## meanderingthemaze (Jan 25, 2010)

JRoque said:


> Thanks Tom/Dan. Good to see we agree on that point. Anyone with a counter argument?
> 
> JR


I like to play devil's advocate so I'll try a counter.

I was talking yesterday to one of the engineers that worked on the EV1 team (so I assume he knows a little bit about EVs) and he brought up a point about electric vehicle motors I hadn't paid any attention to, namely NEMA standards. He pointed out that NEMA developed standards for electric motors in ordinary household appliances and devices in order to raise the quality of production such that all motors had to be built with a safety factor of 4, meaning that they had to be able to withstand 4 times the abuse I suppose than they were rated for. However, when they set out to do the EV1, they decided that since the were building cars, not appliances, that there weren't any standards developed they needed to follow. It was approached as an experimental vehicle anyway. So they didn't build into the motors much room for over abuse.

You can take a 1HP motor and hook it up to a 50HP controller and make that sucker scream, for about 30 seconds before it melts or burns, or explodes. But we want our motors to last a long time, perhaps longer than the car body itself. So, perhaps it would be better to run our motors with less current and less than the max power specs to ensure that they will last longer. In other words, maybe we should be overbuilding these conversions.

Of course we all know the benefits of higher voltage, especially with certain battery chemistries that don't do well under high current loads for long periods of time. Add to that that most battery chemistries are tested for cycle life based on lower current loads (20A maybe?) so higher currents may potentially change what we might expect for longevity. 

Just another point of view.


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## JRoque (Mar 9, 2010)

Hey Kelmark,

My point on that was that if you have 200 connections between your 100 cells, and each connection adds a little bit to the end to end resistance, that might sum up to more than the resistance of a smaller gauge wire - as in 2/0 vs 4/0 cables. So adding a larger gauge cable will not benefit you much.

Hi Naiche. No doubt, higher voltage and lower current is best from an efficiency point of view. I wish they made a 320V cell and I would go for that. 

JR


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## meanderingthemaze (Jan 25, 2010)

JRoque said:


> Hey Kelmark,
> 
> My point on that was that if you have 200 connections between your 100 cells, and each connection adds a little bit to the end to end resistance, that might sum up to more than the resistance of a smaller gauge wire - as in 2/0 vs 4/0 cables. So adding a larger gauge cable will not benefit you much.
> 
> ...


There are pros and cons to both ways. My main point was that longevity of parts could potentially tilt the scales in favor of high voltage. Maybe time will tell. 

Actually ZEBRA batteries, the molten salt ones, come as a self contained box and go really high, like 440V. So even though there are smaller cells inside, it is essentially a single high voltage battery. Too bad the technology doesn't quite seem worthwhile. 

I guess the main reason that they make them small is to fit easier in a range of different applications. But I would much rather have 12V lithiums that were bigger like Lead ones. That would make things cheaper especially on the BMS side.


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## Kelmark (Oct 26, 2009)

Back to the topic of this thread on BLDC motors. Can someone help me understand the true power rating for these three systems? Because I keep coming up with different numbers than what is advertised. Perhaps I should include controller efficiency somewhere in the equation? Or maybe I am missing something important when comparing brushless DC with AC?

1. *HPEV AC-50* @ 96V 550A motor Eff. 89% (Advertised 52hp 115ft pounds “90 actual”)
Amp to Watts Calculator 52800W
.89 x 52800=46992w or 63hp

2. *BLDC 40kw* @ 288V 250A motor Eff. 95% (Advertised 110ft pounds 40kw)
Amp to Watts Calculator 72000W
.95 x 72000=68400w or 91.73hp

3. *BLDC 55kw* @ 312V 195A motor Eff. 90.6% (Advertised 184ft pounds 55kw)
Amp to Watts Calculator 60840W
.91 x 60840= 55364w or 74.24hp

The point of all this is that I keep coming up with the BLDC 40 kw system as being more powerful than the other two. Although the 55kw system has higher peak torque it is probably at lower rpms. I am very interested in the BLDC 40kw system if someone can help me validate that it has a higher power output than the HPEV AC-50.
http://www.electricmotorsport.com/store/ems_ev_parts_motors_ac-induction.php
http://currentevtech.com/Drive-Systems/BLDC-Motors-and-Controllers/40KW-BLDC-Motor-and-Controller-p166.html
http://currentevtech.com/Drive-Systems/BLDC-Motors-and-Controllers/55KW-BLDC-Motor-and-Controller-p175.html


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## meanderingthemaze (Jan 25, 2010)

Kelmark said:


> Back to the topic of this thread on BLDC motors. Can someone help me understand the true power rating for these three systems? Because I keep coming up with different numbers than what is advertised. Perhaps I should include controller efficiency somewhere in the equation? Or maybe I am missing something important when comparing brushless DC with AC?
> 
> 1. *HPEV AC-50* @ 96V 550A motor Eff. 89% (Advertised 52hp 115ft pounds “90 actual”)
> Amp to Watts Calculator 52800W
> ...



Efficiency is a function of other variables. It is not constant. It is best to see if the manufacturers have efficiency graphs. You do also have to take into consideration the efficiency of the controller when looking at over all efficiency of the package. 

Likewise, power output is variable. Continuous ratings are different than Peak ratings. Some motors may have higher peak rating and lower continuous ratings, others might have peak & continuous ratings that are close to each other. Which motor is right for you depends on your needs. If you need 55kW continuous to drive down the street, but use a 40kW continuous rated motor, you may shorten the lifespan of the motor by overstressing it beyond what it was designed to handle.


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## Jan (Oct 5, 2009)

Kelmark said:


> HPEV AC-50[/B] @ 96V 550A motor Eff. 89% (Advertised 52hp 115ft pounds “90 actual”)


96V / sqrt(2) = 68V * 550A = 37,4kW = 50Hp

The sqrt(2) has to do with converting AC to DC. Since this is an AC motor. Why exactly I don't know. Has something to do with sinus waves.


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## tomofreno (Mar 3, 2009)

> The point of all this is that I keep coming up with the BLDC 40 kw system as being more powerful than the other two. Although the 55kw system has higher peak torque it is probably at lower rpms. I am very interested in the BLDC 40kw system if someone can help me validate that it has a higher power output than the HPEV AC-50.


Shaft power of the motor is the product of motor torque and shaft angular velocity as has been pointed out here a number of times. So power = (rpm*torque*2*pi)/(60*0.7376) in the units of kW, if torque is in the units of ft-lb. Power at the wheels will be lower due to drive train losses. Max torque of the AC50 is about 90 lb-ft or 122 N-m. It produces this torque up to about 3000 rpm with a 96V pack, so peak power would be about 38.3 kW or about 51 H.P. Higher pack voltage would give higher H.P. as has also been discussed before. The efficiencies you quote are the maximum efficiencies at higher rpm and low load. At low rpm, during acceleration, or climbing hills the efficiency will be much lower.


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## Kelmark (Oct 26, 2009)

Guys,

Thank you for helping me better understand how to calculate power. I suppose what I need at this point is a performance chart on the BLDC 40 kw system to get the necessary information to properly compare. I.E. Actual torque out to what RPM.

Jacob


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## corbin (Apr 6, 2010)

Kelmark said:


> Guys,
> 
> Thank you for helping me better understand how to calculate power. I suppose what I need at this point is a performance chart on the BLDC 40 kw system to get the necessary information to properly compare. I.E. Actual torque out to what RPM.
> 
> Jacob


My guess (and it is a guess!) is that the BLDC 40kw is pretty much the same as the HPEV AC50 -- both have roughly 40kw max output.

Jacob -- if you do get the graph (maybe email Chris from lowcarbon-idea), please let us know and post it here.

I'm also interested in the 50kw graph; I'm not in the market for a motor, since I already have a Warp9, but I still am interested..

corbin


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## Kelmark (Oct 26, 2009)

corbin said:


> My guess (and it is a guess!) is that the BLDC 40kw is pretty much the same as the HPEV AC50 -- both have roughly 40kw max output.
> 
> Jacob -- if you do get the graph (maybe email Chris from lowcarbon-idea), please let us know and post it here.
> 
> ...


Corbin,

This is what I got from Chris but I do not think it is the same motor as Dave at Current EV Tech is selling. It's not a graph and the numbers don't seem to match up to the one I was interested in?

Jacob


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## corbin (Apr 6, 2010)

Kelmark said:


> Corbin,
> 
> This is what I got from Chris but I do not think it is the same motor as Dave at Current EV Tech is selling. It's not a graph and the numbers don't seem to match up to the one I was interested in?
> 
> Jacob


Jacob,
Your right -- it shows up to 140kw max output at 1700rpm. Maybe that is a 40kw nominal motor, with a higher max output. Given the low RPM, it looks like it is a motor for a bus or something heavy that requires a lot of high torque, low RPMs. Disclaimer: I'm still new to this stuff and could be wrong. I'm interested in how others interpret the data.

corbin


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## JRoque (Mar 9, 2010)

Hi. Something's not jiving with that data and a motor that's sold as 40kW peak. Chris needs to clarify this for us. I have the same data but listed for a 60kW motor so he might have sent data for the wrong motor.

As I understand it, the data displayed is not for a complete performance test but some kind of pass/fail test. I understood the motor can sustain it's specified rating to a higher RPM, closer to 4000 RPM, with a max RPM of 6,000. Chris needs to clarify this for us as well.

JR


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## Kelmark (Oct 26, 2009)

Here is some more information I received from lowcarbon, it not all translated so it it a little hard to read. But it appears these are for a 20kw motor?

Does anyone have information on the BLDC 55kw system Current EV Tech is selling? It is more expensive but I like the weight to power ratio. (Only 30kg)


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