# Agni motors?



## major (Apr 4, 2008)

Woodsmith said:


> I am being prompted to consider Agni motors. It would appear that a pair of them at 10kW each would suit my needs for my MR2 conversion.
> 
> So, what are the pros and cons from experience?


Hi Wood,

I'd pretty much always advise against the use of brushed PM motors for EVs bigger than smaller motorcycles. Now, Agni has put up some big claims about improved construction and even won (I think) the Isle of Mann race. And maybe they are better than what has been available in the past, like Etek, Perm and others, both axial and radial air gap PM motors.

I have used a few PM motors (radial) on some smaller EVs and they did O.K. These were never pressed to the limits. And over the years, I have seen many attempts to use PM motors for traction drives from golf carts to race bikes to forklifts to on-road EVs. Only a very few have had good experience. Most end up with motor failures and ultimately switch to wound field.

Basically, my opinion is that the construction of PM motors (both axial and radial) causes them to be inferior to the stout wound field motor used by most EVers, resulting in durability problems. Having a few percent higher efficiency and a few pounds lighter motor isn't going to mean much when that motor is lying in pieces on the road behind your EV.

Just my opinion. Take or leave it.

major


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## Jozzer (Mar 29, 2009)

Agni motors are fantastic, though you need to spec enough of them for the weight.
Efficiency is great, power to weight is almost unmatched.
THey are NOT to be compared with traditional DC motors, they have solid plate copper as the "windings".
I am currently fitting a pair to a 400kg trike, have a pair on one motorcycle, and one on a lighter bike also. I highly rate this motor as an option, though not sure 2 is enough for a heavy car. Regen is great also.
They will take 400A for a minite, 230 continuos (better with decent cooling), and up to 84v (6000rpm on the reinforced version).
Steve


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## Woodsmith (Jun 5, 2008)

major said:


> Basically, my opinion is that the construction of PM motors (both axial and radial) causes them to be inferior to the stout wound field motor used by most EVers, resulting in durability problems. Having a few percent higher efficiency and a few pounds lighter motor isn't going to mean much when that motor is lying in pieces on the road behind your EV.
> 
> Just my opinion. Take or leave it.
> 
> major


Do you know what caused the failures in durability? 
Is it a design issue, installation issue or use issue? 
How long did the motors run for before they failed?

One of the people asking me to think about them has two in a Ford Fiesta and has been running them without problems for a while.

Jozzer: It would be interesting to see how the trike runs. Which of the motors are you using for the 400kgs?


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## Jozzer (Mar 29, 2009)

I run 95 series reinforced motors on all my vehicles. The same setup runs great on my Ducati
I know of a chap with 100000 miles on a bedford van fitted with a pair of LMC motors (same basic design, also developed by Cedric Lynch)

They are light, which means they cant be overloaded for long. Its much easier to damage them if you dont treat them right, but thats a poor excuse to carry more weight, especially if your vehicle is already fairly light, especially if you have already payed a premium for lightweight battery's.
The new version of this motor comes with a thermister attached, so theres no excuse for overheating them!


If my trike isnt fast enough, I'll just have to add another pair of motors coupled to these on the shaft (mirrored)


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## major (Apr 4, 2008)

Woodsmith said:


> Do you know what caused the failures in durability?


Hey Wood,

Most of the evidence I've seen suggest that the connection to the commutator is a weak link for the radial PM motors. On the axial types, often the comm is actually the armature conductors themselves. But there is some type of joint or clip on the outer edge of the rotor. These fail. Or the armature distorts from heat causing excessive sparking under the brushes and ultimate failure. I have seen the rotor (armature) even come loose on the shaft and rub.



> Is it a design issue, installation issue or use issue?


Yes ,yes and yes. IMHO 



> How long did the motors run for before they failed?


I can't say for sure. People don't send me detailed records 

From anecdotal evidence, like videos, reports, hearsay, the failures occur in the 10 second to 3 week time frame.

Regards,

major


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## Jozzer (Mar 29, 2009)

Sounds like many of these problems have been addressed in the Agnimotor (reinforced banding around the interconnecting strips for example, and thermistor to prevent overheating, which can of course kill ANY motor)

I know of many Perm 132 motors that have failed for the reasons Major gives however (one mine, sparks flames and all due to interconnects parting company with the rotor), I certainly avoid using them now, especially since their support is rather poor.


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## Woodsmith (Jun 5, 2008)

major said:


> From anecdotal evidence, like videos, reports, hearsay, the failures occur in the 10 second to 3 week time frame.
> 
> Regards,
> 
> major


That's too quick to be down to wear and tear. For that sort of failure rate I would be thinking of component failure or faulty installation and use.

Would these be older motors or Perm132 motors as opposed to current range Agni motors?

I can see your concerns towards using them and at the moment it seems like a UK USA difference in feedback. I'm just wondering if that has any bearing on experience? Vehicle weight? Conditions in use? Suppliers and stock?

Jozzer: You and a chap called ChrisB on the BVS site are both running Agni motors and are on the south coast, I am tempted to arrange to came and have a look at them in action if you were willing.


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## Jozzer (Mar 29, 2009)

Ahh, indeed, I didnt notice you were in the UK. Your welcome down to check things out anytime I have motorbikes on the road now, and the trike should be running by the end of next month (hopefuly before).
I know Chris, but didnt know he was using Agni's, thought he had a Berlingo..

I suspect that most US EV'ers have more experience with the Perm and ETEK motors (both based on Cedrics designs, but both took shortcuts Cedric didnt approve of to keep costs down). I imagine I'm one of the few people outside the Agni (and LMC) factory to have tried enough of them to get a fair impression?


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## major (Apr 4, 2008)

Woodsmith said:


> Would these be older motors or Perm132 motors as opposed to current range Agni motors?


Hey Wood,

I am speaking of brushed PM motors in general for use in traction application on heavier vehicles. They simply do not compare to the wound field motors available. Yeah, you get a little higher efficiency and less mass, and regen, for what it is worth. But you pay a high price in both up front dollars and durability.

Maybe Agni has improved construction. Is it good enough to stand up to your application? Pay the price and find out. 

Regards,

major


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## Woodsmith (Jun 5, 2008)

Jozzer said:


> Ahh, indeed, I didnt notice you were in the UK. Your welcome down to check things out anytime I have motorbikes on the road now, and the trike should be running by the end of next month (hopefuly before).
> I know Chris, but didnt know he was using Agni's, thought he had a Berlingo..
> 
> I suspect that most US EV'ers have more experience with the Perm and ETEK motors (both based on Cedrics designs, but both took shortcuts Cedric didnt approve of to keep costs down). I imagine I'm one of the few people outside the Agni (and LMC) factory to have tried enough of them to get a fair impression?


Have a look at my thread on BVS. You will see the photo Chris posted of his motors.

I will happily come down one weekend (or week day when I am not teaching) to have a look and a chat about them. Thanks.


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## Woodsmith (Jun 5, 2008)

major said:


> Hey Wood,
> 
> I am speaking of brushed PM motors in general for use in traction application on heavier vehicles. They simply do not compare to the wound field motors available. Yeah, you get a little higher efficiency and less mass, and regen, for what it is worth. But you pay a high price in both up front dollars and durability.
> 
> ...


I take on board what you are saying Major and I really don't want to pay out to find out unless I can be certain I am finding out good news.

My current thinking is that Agni motors sound promising but buying a fork truck motor would be using proven technology. I am 100% certain that the fork truck motor will give me a solid and dependable vehicle if I find the right motor.
However, for the same resons I am going for LiFePO4 instead of FLA batteries I am looking to see if new and with unproven longevity will prove a good investment in the long run.

The batteries haven't proved their 10 year 10,000 cycle life yet but I am sufficiently convinced that I should go that route and trust it.

For the motor my instincts currently say get a good fork truck motor for around £400 and if Agni motors prove themselves then change it later. However, if I become fairly convinced that the Agni motors are good then I will skip the fork truck motor stage.


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## Jozzer (Mar 29, 2009)

Ahh yes, I remember seeing pics of that fiesta before.
The Agni's are even more powerfull than those motors, and also run to higher RPM's, so should be even more sucessfull.

If your planning a pilgrimage down south, you could perhaps drop in to chat with Cedric too on the way, he's in London mostly (sometimes India, bit more of a commute!)
My numbers/address are on the Jozzbikes website..

Your project looks fun too, must remember to keep an eye on BVS to watch it progress!

Steve


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## Woodsmith (Jun 5, 2008)

Jozzer said:


> Your project looks fun too, must remember to keep an eye on BVS to watch it progress!
> 
> Steve


Most of my write up is here though, in my sig.

I'll arrange a visit when the trike is running.
Cheers,
Alfred


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## major (Apr 4, 2008)

Woodsmith said:


> I take on board what you are saying Major.


Hey Wood,

Below is a quote from a dissatisfied user which I lifted from his web page. He had it on a go-Kart. I know it was a Perm, not an Agni. But this is typical of the kind of thing I see with the PM motors.




> "The Perm PMG-132 motor is now a paperweight. I'm not at all impressed with the motor's durability or the Perm company's response. One of the clips on the outer edge of the armature came loose, and while rattling around, managed to short some of the other windings. The resulting surges burned up some of the contact areas on the commutator. While the motor can still turn, I removed it and replaced it rather than risk damage to the controller.
> 
> Perm's response was that the motor was abused, despite the fact that I monitored the motor temperature, and allowed it to rest if it got to warm. Also, the failure occured when the motor was cold, and the previous run the night before was quite gentle. I got a total of less than 8 hours out of the Perm, so I won't even consider such a motor in the future."


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## Jozzer (Mar 29, 2009)

Aye Major, thats almost exactly what happened to my Perm motor. 
I can see why you would warn against using a motor that performs like the Perm, IMHO it should be used in vehicles that weigh less than person, and don't need to go faster than 50 mph. When they start thermal runaway they last only seconds.

I can catagorically say that the Agni is MUCH MUCH better than this, and will not lose the connecting clips even if it is heated till the solder melts.
Using the same vehicle/pack/controller, the Perm reached 75C in around 6 mins or less and needed babying, where the Agni gets no warmer than 40C.
Efficiency of these small motors is very important, a few percent can add a KW of heat the motor needs to dump very quickly, the Agni (at 93% best and not far off 90% worst) clearly wins here. I believe the Perm is around 87% best, and wouldnt be surprised to hear that it was much worse than this under certain conditions (low RPM or high current).

Cedric keeps a stock of all motor parts, and gives much better customer satisfaction than Perm!


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## Woodsmith (Jun 5, 2008)

Is there any info on how long an Agni motor has been running without problems in a car sized vehicle? 
I think longevity would say a lot for a brand over the failings of the general motor type.


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## Jozzer (Mar 29, 2009)

I think Agni is a fairly new company, searching for LMC's that have been in cars long term may yield more results. I know there are a few in the UK, never heard of problems, I guess thats a good thing.

If you want to wait a year for me to have all the fun I'll let you know how it goes

The motor in Cedrics velomotormobile thing has done more than 100k miles if I remember right, as long as bearings and brushes are checked and caught before they go too far, and thermal limits arn't exceeded, they should last the life the vehicle. I would think the commutator could be refaced, since its the top edge of a copper strip if it did wear. I'm told to expect over 70,000 miles from the brushes, and can see no reason so far why that wont be true given miles covered so far and visible wear. I'm optomistic.


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## Woodsmith (Jun 5, 2008)

I'm happy to see how yours go, and with hope that they are completely trouble free.

It is likely, for financial reasons, that I'll go with a standard fork truck motor to get moving first off. It is a known quantity and with lots of proven history and experience to fall back on. 

I will also keep the Agni motor at the forefront of my mind as an upgrade. Experiencing how yours and Chris' ones perform with the vehicles and over the long term and looking at how the fork truck motor performs with mine may help me determine how many motors I actually need to get the performance I want.


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## Bowser330 (Jun 15, 2008)

Jozzer said:


> Aye Major, thats almost exactly what happened to my Perm motor.
> I can see why you would warn against using a motor that performs like the Perm, IMHO it should be used in vehicles that weigh less than person, and don't need to go faster than 50 mph. When they start thermal runaway they last only seconds.
> 
> I can catagorically say that the Agni is MUCH MUCH better than this, and will not lose the connecting clips even if it is heated till the solder melts.
> ...


http://agnimotors.com/95_Series_Performance_Graphs.pdf

check out the last power graph in the pdf...

26kw @ 4800rpm

72V * 400A * 90+% efficient

They used two of these motors to power their winning EV sport bike the TTXGP.

About 1300$ each...


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