# Why are DC motor modifications so costly?



## somanywelps (Jan 25, 2012)

Bowser330 said:


> I read an article that Black Currant's siamese 9" motors were 10,000$....
> 
> Seeing as 9" Series motors can be found in junkyards for a few hundred dollars each, I am wondering what the other 9,500$ is for...even purchased refurbished/new for EV normal use they can be purchased for 1,600$ each, so 2X = 3,200$...so to siamese the motors and upgrade them further costs...6,700$?? I found a link advertising "Jimpluse9" for ~5000$ in 2008. Did the price really double in 3 years?
> 
> ...


Kostov dual 9"s are pretty cheap...


----------



## Bowser330 (Jun 15, 2008)

somanywelps said:


> Kostov dual 9"s are pretty cheap...


Im not sure they have all the performance upgrades that the Jimpluse9's do...


----------



## somanywelps (Jan 25, 2012)

Bowser330 said:


> Im not sure they have all the performance upgrades that the Jimpluse9's do...


That's probably why they're so costly.

Remember man-hours for labor and R&D.


----------



## major (Apr 4, 2008)

Bowser330 said:


> I read an article that Black Currant's siamese 9" motors were 10,000$....


What would be the cost of a modified VW engine and transmission which could yield similar performance on the track?


----------



## Bowser330 (Jun 15, 2008)

major said:


> What would be the cost of a modified VW engine and transmission which could yield similar performance on the track?


hahaha good point...I don't think that's even possible and definitely not reliably with only 10K$....

Major, everyone knows you know your motor tech...

Is there really some kind of magic that goes into the siamese impulse 9's?

If the cost is really driven by the machining & assembly time/labor to siamese the motors then I will understand that, I am more interested in knowing the specific motor upgrades, bearings, terminals, kevlar, latest brushes, etc (the list above) is that really it?

For example, I know what a dual armature is, I've seen the pictures showing two armatures on a single shaft, each with their commutators on the far ends....









however, I have not been able to find a good picture on the web of a "dual commutator", which Netgain has advertised...can you help describe that to me? Also, how does that help the voltage handling of the motor? 

I found this picture but I am not sure it helps much...


----------



## major (Apr 4, 2008)

Bowser330 said:


> Is there really some kind of magic that goes into the siamese impulse 9's?


Nah, it's all driver skill 



Bowser330 said:


> however, I have not been able to find a good picture on the web of a "dual commutator", which Netgain has advertised...can you help describe that to me? Also, how does that help the voltage handling of the motor?


Sorry, I have no idea what that is all about 

My point would be that these electric motors used to set these "records" aren't excessively costly. I don't think John has "built" motors in his DCPlasma


----------



## Bowser330 (Jun 15, 2008)

major said:


> Nah, it's all driver skill
> 
> 
> 
> ...


very true, i believe he just has two off the shelf warp9's coupled together...hmmm


----------



## Plamenator (Mar 6, 2009)

A dual commutator is actually a longer one.
Normally commutators accomodate 8 brushes in 4 rows.
A longer one can take 12 or 16 brushes (still in 4 rows but 4 in a row).

This is done in order to spread the current and in some cases results in lower commutator and brush temperature. It can be done if arcing is a problem or if amps per sq.mm of brush surface were over the norm.

Making it longer has 2 drawbacks:
1) More brushes mean more friction so if arcing/amps were not a problem initially, going to 16 brushes actually heats up the commutator.
2) A longer commutator experiences more centrifugal force and is more prone to exploding.

Actually our K13" DirectDrive was with 16 brushes initially.
We reduced those to 8 and shortened the commutator to achieve higher continuous rpm.
Result was very good.
But this was an interpoled motor to start with so it never had arcing problems.


----------



## major (Apr 4, 2008)

Plamenator said:


> A dual commutator is actually a longer one.


I thought that might be it. Kinda stretches the definition of dual.


----------



## somanywelps (Jan 25, 2012)

Plamenator said:


> A dual commutator is actually a longer one.
> Normally commutators accomodate 8 brushes in 4 rows.
> A longer one can take 12 or 16 brushes (still in 4 rows but 4 in a row).
> 
> ...


Does this have anything to do with why your 9" 220V has such a high RPM rating?


----------



## Bowser330 (Jun 15, 2008)

Plamenator said:


> A dual commutator is actually a longer one.
> Normally commutators accomodate 8 brushes in 4 rows.
> A longer one can take 12 or 16 brushes (still in 4 rows but 4 in a row).
> 
> ...


The #2 drawback is sort of a catch-22...the whole point to add the extra comm would be to add more collector bar to brush interaction points to spread the power out so there is less chance for arcing....meaning you can increase the voltage of the motor and thus the rpm of the motor....but the catch is...the extra weight of that added assembly increases the centrifugal forces which can lift the bars and destroy the motor...

I guess i don't see why with the extra comm & brushes the motor couldnt draw full amperage at least up to its redline...Warp9 5500rpm?


----------



## Plamenator (Mar 6, 2009)

somanywelps said:


> Does this have anything to do with why your 9" 220V has such a high RPM rating?


Not really - it can go that high because it is much smaller in diameter than the 10/11" commutators.
Technically, if we make it a 16 brush comm, redline rpm will fall but biggest factor is smaller comm.


----------



## Plamenator (Mar 6, 2009)

Bowser330 said:


> I guess i don't see why with the extra comm & brushes the motor couldnt draw full amperage at least up to its redline...Warp9 5500rpm?


I guess only George Hamstra knows 
It depends a lot on the commutator construction.
If you do it properly 5500rpm can be continuous rather than peak...or should I say "burst" (Chinese battery producers seem to like that term a lot heheh).


----------



## Bowser330 (Jun 15, 2008)

Plamenator said:


> Technically, if we make it a 16 brush comm, redline rpm will fall but biggest factor is smaller comm.


So you are saying that the extra weight of having a longer commutator will cause the motor's "redline rpm" to be decreased due to the additional weight affecting the centrifugal forces and lowering the speed at which the comm. bars may lift and cause armature destruction....is that correct?

http://kostov-motors.com/tractionmo...esdcmotorsforelectricvehicles/k13directdrive/

The K13 looks like a serious machine! 
240V = 4450rpm, what is the redline of this motor with the smaller comm.? 5,500rpm?

What would the redline have dropped too if you have left the longer comm. with 16 brushes?


----------



## somanywelps (Jan 25, 2012)

Plamenator said:


> Not really - it can go that high because it is much smaller in diameter than the 10/11" commutators.
> Technically, if we make it a 16 brush comm, redline rpm will fall but biggest factor is smaller comm.


Sorry to bother you, but in another thread you mentioned that the 6800RPM nominal of the 9" 220V was ok, but 8000RPM was an acceptable temporary peak redline. Did I interpret that correctly?

That would involve higher than 220V?


----------



## Plamenator (Mar 6, 2009)

Bowser330 said:


> So you are saying that the extra weight of having a longer commutator will cause the motor's "redline rpm" to be decreased due to the additional weight affecting the centrifugal forces and lowering the speed at which the comm. bars may lift and cause armature destruction....is that correct? YES!
> 
> The K13 looks like a serious machine!
> 240V = 4450rpm, what is the redline of this motor with the smaller comm.? 5,500rpm? IT WILL INCREASE A LOT OF COURSE BUT WILL REDUCE MAX AMPS IT CAN HANDLE.
> ...


See my replies in quote above.


----------



## Plamenator (Mar 6, 2009)

somanywelps said:


> Sorry to bother you, but in another thread you mentioned that the 6800RPM nominal of the 9" 220V was ok, but 8000RPM was an acceptable temporary peak redline. Did I interpret that correctly?
> 
> That would involve higher than 220V?


Did I not mention 8000 is "unofficial" in that post?
We have only tested 6800.
I suppose 8000 will also hold as peak but cannot back that up by real data

You can have 8000 at 220V if amps are less than nominal.
Motor can operate at 250V as far as commutation is concerned.
Problem is 250V implies nominal rpm that I am not comfortable with.


----------



## somanywelps (Jan 25, 2012)

Plamenator said:


> Did I not mention 8000 is "unofficial" in that post?
> We have only tested 6800.
> I suppose 8000 will also hold as peak but cannot back that up by real data
> 
> ...


Understood, my car is nothing more than a parts list at this point 

Primary objective is to make sure I don't wind up blowing up something.


----------



## Bowser330 (Jun 15, 2008)

Plamenator, can you please give us more information of the K11 Alpha?


----------



## Plamenator (Mar 6, 2009)

It was inspired by my Z4 conversion.
Maybe you know that K11" 250V only handles 210A continuous at 250V.
This was irritating me a lot so we made this motor that is something like 50-53kW/230V/5600rpm/90Nm continuous. For overload purposes one can use a 250-288V battery so rpm stay high under overload conditions.

I was also unhappy with the standard shaft mounted fans as ventilation was rpm dependent. I.E. if you have 1/3 of nominal rpm, your ventilation is like 3 times weaker. Further the standard fans tend to make lots of whining noise at 4000+ rpm. So we re-introduced the specially shaped back flange that you see on the picture to allow forced air cooling to pump more air through the motor. 

As this back flange makes it impossible to use it for mounting, we added machined platforms with threads in the motor case so one can hang the motor on those - there are 4 platforms/8 threads in total.

The motor can also come with an SKF sensor bearing producing 80 pulses per revolution - it is automotive class (used in car ABS systems) and is extremely reliable and maintenance free (unfortunately Soliton/Zilla cannot read it ).


----------



## Batterypoweredtoad (Feb 5, 2008)

Planetmotor-can you post more info about this motor in its own thread or maybe on this one: http://www.diyelectriccar.com/forums/showthread.php?p=288288&posted=1#post288288

I am really curious about it. Will it handle 1000Amps for any length of time? Do you have the motor performance graphs? Etc...


----------



## somanywelps (Jan 25, 2012)

Plamenator said:


> It was inspired by my Z4 conversion.


I thought you were doing something using AC?


----------



## Duncan (Dec 8, 2008)

somanywelps said:


> Understood, my car is nothing more than a parts list at this point
> 
> Primary objective is to make sure I don't wind up blowing up something.


As opposed to my philosophy of expecting to blow things up and then replace them with stronger ones


----------



## Plamenator (Mar 6, 2009)

Batterypoweredtoad said:


> Planetmotor-can you post more info about this motor in its own thread or maybe on this one: http://www.diyelectriccar.com/forums/showthread.php?p=288288&posted=1#post288288
> 
> I am really curious about it. Will it handle 1000Amps for any length of time? Do you have the motor performance graphs? Etc...


No performance graphs for the moment as I am still wondering how to market it. I.E. be realistic or adopt the methods of our competition and claim a ridiculous figure like 288-300V


----------



## Plamenator (Mar 6, 2009)

somanywelps said:


> I thought you were doing something using AC?


I wanted to use a dual AC motor at the beginning. Like 2 of those:
http://kostov-motors.com/tractionmo...forelectricvehicles/10ac9motor-controllerkit/

But the 1238R is very limiting with its 650A/96VDC.
A dual motor would have been only 100kW peak and I wanted 150kW so opted for Soliton1+K11" 250V.

Funny enough but finally I ended up with 90kW peak as the 90Ah Winston cells I chose only give me 500A peak


----------



## Batterypoweredtoad (Feb 5, 2008)

Plamenator said:


> No performance graphs for the moment as I am still wondering how to market it. I.E. be realistic or adopt the methods of our competition and claim a ridiculous figure like 288-300V


I like how you do it in your "Why Interpoles" explanation on your website. I would love to see a continuous rating (S60?) and then lower time limits all the way down to 1 minute rating with heat gain for each.


----------



## Plamenator (Mar 6, 2009)

Our dyno is high voltage but only goes to 600A.
60min is 260A while 500A are 4min.


----------



## efan (Aug 27, 2009)

Plamenator said:


> I wanted to use a dual AC motor at the beginning. Like 2 of those:
> http://kostov-motors.com/tractionmotors/kostovevmotors(ac-dc)/3-phaseacmotorsforelectricvehicles/10ac9motor-controllerkit/
> 
> But the 1238R is very limiting with its 650A/96VDC.
> ...


this is a bit off topic, but I wanted to see if Plamenator could enlighten us on the pricing of the low power AC systems that are available to the diy community.
I realize that the AC package offered by Kostov motors is at a better price and I am sure equivalent quality to the HPCG AC-50...and I give you credit for that. But for ~$3600 one can purchase a Soliton jr and K9" -220v motor for much better performance. 
So why is the AC system at half the power (or worse) of the DC so costly? is the controller the expensive component? or is the motor more complex and costly to produce compared to a DC one? at this price we are looking at $12,000 for 150kw package...not much better than a UQM or AC Propulsion System.


----------



## somanywelps (Jan 25, 2012)

Batterypoweredtoad said:


> I like how you do it in your "Why Interpoles" explanation on your website. I would love to see a continuous rating (S60?) and then lower time limits all the way down to 1 minute rating with heat gain for each.


This would be infinitely useful. 


Plamenator said:


> I wanted to use a dual AC motor at the beginning. Like 2 of those:
> http://kostov-motors.com/tractionmo...forelectricvehicles/10ac9motor-controllerkit/
> 
> But the 1238R is very limiting with its 650A/96VDC.
> ...


Is that peak a limit of the controller or the motor (or both)? 

Would something like this be more appropriate?: http://www.tritium.com.au/products/TRI74/index.html


----------



## Plamenator (Mar 6, 2009)

efan said:


> this is a bit off topic, but I wanted to see if Plamenator could enlighten us on the pricing of the low power AC systems that are available to the diy community.
> I realize that the AC package offered by Kostov motors is at a better price and I am sure equivalent quality to the HPCG AC-50...and I give you credit for that. But for ~$3600 one can purchase a Soliton jr and K9" -220v motor for much better performance.
> So why is the AC system at half the power (or worse) of the DC so costly? is the controller the expensive component? or is the motor more complex and costly to produce compared to a DC one? at this price we are looking at $12,000 for 150kw package...not much better than a UQM or AC Propulsion System.


Actually an aluminium die casted AC motor is cheaper to manufacture than a DC one. In our case we buy the rotor/stator laminations (volumes are very small and do not justify producing the press tool for cutting laminations) so cost of K9 and 10AC9 is similar. Sensor bearing adds a bit but more or less the same.
Curtis 1238 is expensive indeed and probably comes around 2300-2500$ with spyglass, connector kit, import duties, customs fees, transport and a little profit.
Then I look at price of competitors and beat it somewhat but not too much 

Can you freely buy AC propulsion/UQM products?

Also have in mind that brushed series DC motor produces the best performance of all technologies. It is simply not reliable due to commutator/brushes/low IP. Hence for any other technology to match, their motor has to be bigger (or cheat with higer voltage). So not very fair to compare a 45kg K9 motor meant for 220V with a 40kg AC one.


----------



## Plamenator (Mar 6, 2009)

somanywelps said:


> This would be infinitely useful.
> 
> 
> Is that peak a limit of the controller or the motor (or both)?
> ...


 
We designed the motor to match controller's peak amps of 650A.
Motor itself can take even 1000A but for very short periods and I think it is dangerous to do it on a 40kg unit.

I know of Tritium for some time now.
Even have designed an 11"AC motor for it (380VDC, 100kW peak if I remember correctly) but never made a prototype. Tritium is just so expensive at 7000$...and it has no CE so kind of difficult to import it in Europe.

Anyone aware of suitable motors for Tritium?


----------



## rochesterricer (Jan 5, 2011)

efan said:


> at this price we are looking at $12,000 for 150kw package...not much better than a UQM or AC Propulsion System.


Not much better? From what I recall, when people can actually get a quote from those companies, a 150kw system comes in at more than double that price.


----------



## efan (Aug 27, 2009)

rochesterricer said:


> Not much better? From what I recall, when people can actually get a quote from those companies, a 150kw system comes in at more than double that price.


I haven't heard of any recent quotes, but you can certainly find a used system...I know of an AC Propulsion system that is being sold for $19k...and few days ago there was a UQM 150kw package offered for $14K (I believe its gone now)!


----------



## efan (Aug 27, 2009)

Plamenator said:


> Actually an aluminium die casted AC motor is cheaper to manufacture than a DC one. In our case we buy the rotor/stator laminations (volumes are very small and do not justify producing the press tool for cutting laminations) so cost of K9 and 10AC9 is similar. Sensor bearing adds a bit but more or less the same.
> Curtis 1238 is expensive indeed and probably comes around 2300-2500$ with spyglass, connector kit, import duties, customs fees, transport and a little profit.
> Then I look at price of competitors and beat it somewhat but not too much
> 
> ...


I always taught that if you compared an AC and a DC motor at the same voltage and amps, you will have a better EV motor from the AC...more usable torque range etc.

all that information on the price of motors sounds very encouraging, since if a more affordable AC controller became available going with AC vs DC will make much more sens. And I LOVE how you try to price your product a bit better than the competitor!


----------



## Qer (May 7, 2008)

efan said:


> I always taught that if you compared an AC and a DC motor at the same voltage and amps, you will have a better EV motor from the AC...more usable torque range etc.


Noooooo...

You will have a bigger RPM-span with AC, but since power out is RPM*torque it will mean that where the AC-motor will give higher RPM, the DC-motor will give higher torque. Also, it's apparently very hard to get high torque at zero RPM in an AC-motor (some controlling algorithms are better than others, but it seems that at zero, really zero RPM, they all kinda suck compared to DC) where a serial wound DC-motor will give you insane amounts of torque (if you can provide the current, that is  ) which, as far as I know, no AC-motor can match.

So which is better? Depends. It's like comparing Catholicism with Protestantism. You're doomed to be accused of blasphemy no matter what you choose. 

However, I've said it before and I say it again. There's no "better" system, there's just different pros and cons and whichever system that fit you the best depends on a lot of factors like price, regen, performance, cooling etc, and in the end you have to compare systems rather than technologies.

You have to compare a complete set of batteries, controller/inverter and motor with another set-up to be able to tell which is "best", you can't just kinda claim "X is better for Y!" without first defining what X and Y is. And no, X can't be AC or DC and Y can't just be EV's in general. It's too foggy to be useful for anything but propaganda or trolling.


----------



## efan (Aug 27, 2009)

Qer said:


> You have to compare a complete set of batteries, controller/inverter and motor with another set-up to be able to tell which is "best", you can't just kinda claim "X is better for Y!" without first defining what X and Y is. And no, X can't be AC or DC and Y can't just be EV's in general. It's too foggy to be useful for anything but propaganda or trolling.


First of, I am not saying which is better and which worse, since I dont know the answer. You say more details are needed, fair enough.
Lets then say that we are interested in an everyday car (NOT a drag racing car but an everyday car to drive to work, school, the store etc. without of course causing traffic backup at the light or highway)...looking for a reliable system(minimal maintenance both on car and electric drive system, eliminate the transmission if possible)...lets also say that the system must have good cooling because it needs to operate in an area where the highway system includes frequent steep hills...and since the only available/some what reasonably priced AC system is in the range of 96v -120v and 650amps, lets consider a battery pack that can deliver just that...120vdc and 650amps (with such power levels one definitely needs to keep the transmission). Without any propaganda or trolling what would the better choice be?


----------



## rochesterricer (Jan 5, 2011)

efan said:


> I haven't heard of any recent quotes, but you can certainly find a used system...I know of an AC Propulsion system that is being sold for $19k...and few days ago there was a UQM 150kw package offered for $14K (I believe its gone now)!


Well now you're comparing new vs used. Kinda apples vs oranges.


----------



## Qer (May 7, 2008)

efan said:


> looking for a reliable system(minimal maintenance both on car and electric drive system, eliminate the transmission if possible)...lets also say that the system must have good cooling because it needs to operate in an area where the highway system includes frequent steep hills...and since the only available/some what reasonably priced AC system is in the range of 96v -120v and 650amps, lets consider a battery pack that can deliver just that...120vdc and 650amps (with such power levels one definitely needs to keep the transmission). Without any propaganda or trolling what would the better choice be?


Either. 

Reliability; the general problem is that cheap crap is cheap crap. Most people that has lots of maintenance problems with their EVs has it because they cheapened out and got some low quality crap that blew up.

The brushes isn't really a problem, there's a bunch of old EVs that were imported to Sweden in the 90's (mostly Renault Clios) and most of the ones that has been scrapped was scrapped because the batteries can't be replaced (old flooded NiCd and there's an environmental tax on Cadmium that makes new batteries insanely expensive) or the electronics blew up. I don't know of any of them that has needed new brushes despite that some of them have reached 6 digit miles.

If you constantly overheat the brushes (like regularely run 1kA through a WarP 9") you'll cause excessive brush wear, sure, but at 4 times the specified current you're kinda asking for problems. 

Cooling; an AC motor can be water cooled, sure, but it's just parts of the motor that's water cooled. The armature is still air cooled (no way of water cooling a rotating lump of metal unless, of course, you spray it with water, which you don't in an AC motor). It's possible the water cooling of an AC motor actually improve overall cooling, but it also adds the complexity (and the point of failure) of having to have a water based cooling system where a DC-motor can get a blower attached for improved cooling.

Having the ability to handle steep hills (especially without a gear box) is only a matter of enough power and, of course, the capability to get rid of excess heat. A properly designed system will manage it, an underpowered system (or a cooling system that doesn't meet the requirement) won't.

If you live where it's hilly or if you do a lot of stop and go regen might be a thing worth considering. On the other hand, maybe a regen capable system will be so expensive so it's easier to just buy a few more batteries (to compensate for the losses) and still save some bucks. If you live where it's flat and you don't drive much in a city regen is probably pointless and only waste of money.

So which system will be best? The one that can provide enough power for your requirement. What is enough power? Depends on what car you choose to convert. It's just a question of physics; weight, air resistance, climb ratio etc. It boils down to a certain power and torque requirement and from there you can start looking at whatever system you need.

There simply isn't a simple A or B-answer so my best advice is:

If you're serious about starting a conversion and you really want to do your own EV, start your own build-thread, begin with explaining what car you want to convert (a pickup, a van, an ordinary car etc), if you have some ideas of brands you think might fit, what you expect to use it for, what range, speed, acceleration etc you wish to achieve etc and take it from there.

AC or DC is a minor detail and before you're even at a position where you can do an intelligent choise (rather than just based on feelings or rumours) there's a lot of other considerations you have to sort out.


----------



## bjfreeman (Dec 7, 2011)

I looked At DC motors but could not find one in the 150KW range that was used in the EV world. The DC traction motors faced lot of maintenance, commutation and flash over with other associated problems during operation 
Over and above, the DC traction motors have low kW/kg ratio which made the traction drive very uneconomical 
I researched more and found three-phase squirrel-cage (induction) AC traction motor on inverter supply made the traction drive most economical with high kW/kg ratio and also reducing the unsprung mass on the axle 
Aluminium die cast rotor bars are used since 1930








The greatest advantage of using aluminum alloy rotor bars in the three-phase squirrel-cage A.C. traction motor is high starting and running torque (i.e. more tractive effort), improved starting power factor and weight reduction, thereby reducing the cost of machines and achieving high kW/kg of the traction motor. 
There is an increase in starting torque by more than 25% with significant improvement in the torque – slip characteristics, power factor during starting goes up to about 0.75 whereas for conventional induction motors the power factor is in the range of 0.35 to 0.45 during starting. 
I also noticed that poles were an important part of determine Torque. The more Poles the more Torque. Adding Poles reduces the RPM for a given frequency this is easily compensated for in the PMW control. Poles are the number of sets of three-way electromagnetic windings that a motor has. Each set of Poles bring make how far the rotor has to move to be under the influence of the next set of poles, hence more torgue


----------



## Bowser330 (Jun 15, 2008)

Plamenator said:


> We designed the motor to match controller's peak amps of 650A.
> Motor itself can take even 1000A but for very short periods and I think it is dangerous to do it on a 40kg unit.
> 
> I know of Tritium for some time now.
> ...


Besides the carbon fiber motor that the prototypes were built with... (i think the motors cost 15K$)

All the motors that have been discussed thus far are ~7-11K$...Remy, AFM, etc.


----------



## Qer (May 7, 2008)

bjfreeman said:


> The DC traction motors faced lot of maintenance, commutation and flash over with other associated problems during operation


If you abuse them, yes. If you keep within (or at least reasonably close to) specs, no.

There's a few hundred SepEx-powered EVs in Sweden that were imported during the 90's and about half of them are still operational. Most (all?) of the other half were scrapped due to battery and electronic problems (there's been a bit of scavenging to keep as many as possible rolling), don't know of a single one that was scrapped due to motor problems and brush maintenance isn't really a huge maintenance concern as well.

If you, for example, regularly push 1kA through a WarP 9" odds are that something's gonna break eventually, which isn't really surprising considering it's about 4 times the rated current...

Kindly fine tune your opinion to more realistic levels.


----------



## bjfreeman (Dec 7, 2011)

Qer said:


> If you abuse them, yes. If you keep within (or at least reasonably close to) specs, no.
> 
> There's a few hundred SepEx-powered EVs in Sweden that were imported during the 90's and about half of them are still operational. Most (all?) of the other half were scrapped due to battery and electronic problems (there's been a bit of scavenging to keep as many as possible rolling), don't know of a single one that was scrapped due to motor problems and brush maintenance isn't really a huge maintenance concern as well.
> 
> ...


If it helps, I use to build DC motors from the ground up.
They were part of our product. we had some out for decades.
My Grandfather started building them in early 30's and they were still in fishing boats.
It is also how they are built and as you say in spec.
What I was referring to was DC in the 150kw and above range.


----------



## Qer (May 7, 2008)

bjfreeman said:


> What I was referring to was DC in the 150kw and above range.


Are there even anyone manufacturing DC-motors at 150 kW and above aimed for EV-use? Kostovs motors are between 18-65 kW each and I don't think WarPs are rated much higher. That's of course continuous power though (well, ok, 60 minute rating)...

I'm not saying that you can't blow a motor to Kingdom Come (pushing 1kA through a 9" will make it blow up within half a minute, empirically tested), only that "The DC traction motors faced lot of maintenance, commutation and flash over with other associated problems during operation" is an exaggeration. Anything pushed way off the scale will blow, no matter what.

I saw some mad russian guys set fire to a BMW (500-something I think) by simply skidding for so long that the catalytic converter started to melt (it literally dripped melted metal) which led to the car catching fire and burn up. Does that make BMWs facing problems with melting converters and catching fire? Not if you're behaving relatively sane behind the wheel, not really.

There's no reason a DC-motor in a well balanced design (where the cars weight, the controllers settings etc are properly in tune with the motor) shouldn't be reliable. If you're going for an all out design where you know you're pushing things way out of specs you kinda have to expect that eventually something's gonna give.

They do in the ICE-world, why would EV's be any different?


----------



## somanywelps (Jan 25, 2012)

Plamenator said:


> Anyone aware of suitable motors for Tritium?


The HVH250s and the AF-130/140/230/240s


----------



## LithiumaniacsEVRacing (Oct 9, 2010)

Plamenator said:


> I guess only George Hamstra knows


Yes, that is the understatement of the year. All these "Motor Pro's" and only one company (not including Dennis Berube) has produced the fastest DC motors in the 1/4 mile. Netgain motors are breaking all the records, along with Dennis Berube's motors. Stick around, this summer we will be installing two 11" DC motors in our 2012 Camaro that beats all competition in the business.

There is a huge benefit to additional brushes, comms, brush material, angles, cooling, and designs in general. In 2012 we will operate where no man has gone before!


----------



## bjfreeman (Dec 7, 2011)

Qer said:


> Are there even anyone manufacturing DC-motors at 150 kW and above aimed for EV-use? Kostovs motors are between 18-65 kW each and I don't think WarPs are rated much higher. That's of course continuous power though (well, ok, 60 minute rating)...
> 
> I'm not saying that you can't blow a motor to Kingdom Come (pushing 1kA through a 9" will make it blow up within half a minute, empirically tested), only that "The DC traction motors faced lot of maintenance, commutation and flash over with other associated problems during operation" is an exaggeration. Anything pushed way off the scale will blow, no matter what.
> 
> ...


Your way off track of my orginal post. I require 250KW minimum. though there are dc motors way above of this, used in Train traction motors, the problems I specified are ones told me by the company that repairs them.


----------

