Is Kostov motors still in business?
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Ok, so I've managed to get them on the phone, and received the bad news.
Kostov doesn't produce EV motors anymore!
They only make industrial motors, they say that there wasn't enough interest. Which is really a shame, they had some pretty unique models which you just can't buy anymore from other manufacturers.
Kostov doesn't produce EV motors anymore!
They only make industrial motors, they say that there wasn't enough interest. Which is really a shame, they had some pretty unique models which you just can't buy anymore from other manufacturers.
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Not enough interest because its a very very limited niche business and many who are now getting into converting are using AC motors instead. Much easier and cleaner. Limited on what they can use but that is changing as we move along. One successful company is HPEVS in California. They use the Curtis AC inverter very successfully and can be used in plenty of different sized vehicles including motorcycles. I see the benefit over DC systems. I have an industrial 11" Kostov motor with interpoles. Works fine. Bulky external cooling fan takes a bit of room. Not the most robust commutator. Designed for torque and low speeds in industrial equipment but they are usable in vehicles.
http://www.diyelectriccar.com/garage/cars/471
http://www.diyelectriccar.com/garage/cars/471
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You driven an AC drive electric recently? If not you'd be pleasantly surprised. Very robust and powerful. Yes, more expensive but that will change too. People are working on DIY inverters that are rather robust and you can build your own power section to dish out a crap load of power.
Run two and gain more. Affordable inverters.
Pete
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Hi riba
What is the difference between an "industrial motor" like a forklift and one used in an EV?
As far as I can see the difference is a coat of paint and an extra $1000
Kostov will still be making the motors - they have simply stopped trying to market them to a small and troublesome market sector
You will still be able to buy them - just say it's for a forklift
What is the difference between an "industrial motor" like a forklift and one used in an EV?
As far as I can see the difference is a coat of paint and an extra $1000
Kostov will still be making the motors - they have simply stopped trying to market them to a small and troublesome market sector
You will still be able to buy them - just say it's for a forklift
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Well, 150kw is 150kw, whether it's from AC or DC motor. I don't argue that AC motor can be powerful, but that comes with it's price.You driven an AC drive electric recently? If not you'd be pleasantly surprised. Very robust and powerful. Yes, more expensive but that will change too. People are working on DIY inverters that are rather robust and you can build your own power section to dish out a crap load of power.
Run two and gain more. Affordable inverters.
Pete
Yeah, DIY inverter plus rewound industrial 3f induction motor is great budget combination, but after all I've been through, I've just wanted something plug and play.
Difference is huge, just look at power to weight ratio. If I wanted something like that I would search local used forklift motors, for much lower price and without waiting time.
But for me it doesn't matter anymore, I have kostov K11 alpha and zeva 1000 amp controller, I'll just connect motor's field in parallel and voila
But I wanted to buy smaller kostov at first.
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Hi Riba
Have a good look at those motors
There is NO - zero - physical difference between the two!
The difference is purely in the way that they are described!!
The laminations wiring and comms are identical
The only things that you have to "play with" are
The brush material
The bearings
The "advance" - which is unnecessary in a motor with interpoles
So you can change the brushes (if you want to - I don't believe it will make a significant difference)
Change the bearings - I would be AMAZED if the originals are not as good as you can get
Advance the brushes for higher rpms and voltage
The rest is EXACTLY the same - except the price!
Have a good look at those motors
There is NO - zero - physical difference between the two!
The difference is purely in the way that they are described!!
The laminations wiring and comms are identical
The only things that you have to "play with" are
The brush material
The bearings
The "advance" - which is unnecessary in a motor with interpoles
So you can change the brushes (if you want to - I don't believe it will make a significant difference)
Change the bearings - I would be AMAZED if the originals are not as good as you can get
Advance the brushes for higher rpms and voltage
The rest is EXACTLY the same - except the price!
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If I've looked correctly, this is the closest industrial replacement:
http://kostov-motors.com/tractionmotors/dcseriesmotors/framesize220mm/
The 120V one. It has les power, slightly lower voltage, and no interpoles. Also I don't see the weight, it's probably a bit higher but ok.
These are 66 kg, and only 7 kw:
http://kostov-motors.com/tractionmotors/dcseriesmotors/framesize248mm/
So definitely worse power to weight, just not so suitable for vehicle.
http://kostov-motors.com/tractionmotors/dcseriesmotors/framesize220mm/
The 120V one. It has les power, slightly lower voltage, and no interpoles. Also I don't see the weight, it's probably a bit higher but ok.
These are 66 kg, and only 7 kw:
http://kostov-motors.com/tractionmotors/dcseriesmotors/framesize248mm/
So definitely worse power to weight, just not so suitable for vehicle.
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Hi riba
You are not listening!!
The motor is the same - same wiring same com
The ONLY difference is the way that it is rated!
Industrial motors are rated at 1 hour - EV motors at about 1 minute
the forklift motor on my car is rated at 10Kw
My controller can give it 340v and 1200amps
You are not listening!!
The motor is the same - same wiring same com
The ONLY difference is the way that it is rated!
Industrial motors are rated at 1 hour - EV motors at about 1 minute
the forklift motor on my car is rated at 10Kw
My controller can give it 340v and 1200amps
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Nope, you are not right. Kostov ev motors are also rated for 60 min cycle. And like I've said, ind. motor has no interpoles, and thus lower power and torque. Also, EV motors have high speed comutator and better banding, so they can spin much faster.
If what you're saying is true, why would they even bother to develop special EV versions?
I'm not saying that industrial motors are not good or usable, but you simply can not treat them as equals.
If what you're saying is true, why would they even bother to develop special EV versions?
I'm not saying that industrial motors are not good or usable, but you simply can not treat them as equals.
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Yeah
A 60 minute cycle - 5 mins ON 55 mins OFF
As opposed to 60 mins ON
Adding interpoles - reduces torque and power!
But it does allow for higher rpm/voltage
Advancing the brushes does the same - with the disadvantage that running the motor backwards increases comm/brush wear - a big problem for a forklift - not such a biggy for an EV
Get the two motors in front of you - have a good look - physically they are the same - a fresh coat of paint and different numbers on the side may convince the customers but the gods of engineering need a wee bit more
A 60 minute cycle - 5 mins ON 55 mins OFF
As opposed to 60 mins ON
Adding interpoles - reduces torque and power!
But it does allow for higher rpm/voltage
Advancing the brushes does the same - with the disadvantage that running the motor backwards increases comm/brush wear - a big problem for a forklift - not such a biggy for an EV
Get the two motors in front of you - have a good look - physically they are the same - a fresh coat of paint and different numbers on the side may convince the customers but the gods of engineering need a wee bit more
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No, please read more carefully before posting. Ind. motors - S2-60. EV motors - S2-60. So, the same rating.
Motor with interpoles has more toque and can withstand more voltage compared to advancing brushes, so it's better in every way. Basically, much better power to weight which I've pointed out to be main advantage (interpoles + higher RPM - more power from same package).
Quote from kostov FAQ:
IS THERE ANY EMPIRICAL EVIDENCE ON THE EFFECT OF THE INTERPOLES? http://kostov-motors.com/
We have performed tests on an interpoled Kostov 9" 80V motor. One would think that 80V is relatively low and does not justify the use of interpoles. Indeed it may be so for low rpm, low amp forklift motors but the data shows this not to be true for EV conversion motors. For example most good EV motors have more than 4000rpm and 200A. The Kostov 9" 80V usually has collector temperature change of 120K in 60 minutes of work (up to 140K according to standard) at 280A. Removing the interpoles results in temperature change ot 157K in JUST 10 minutes. Advancing the brushes by 8/12 degrees improves the number to 147/141K but still in only 10 minutes. SHOULD THE BRUSHES OF AN INTERPOLED MOTOR BE ADVANCED? http://kostov-motors.com/
The interpoles create a magnetically neutral point whose position is independent of rotation direction, rpm, amps or voltage. The brushes are positioned exactly in this point. Advancing them will result in moving away from the neutral zone and will worsen commutation/arcing drastically. This, in turn, can have very bad consequences for the motor. HOW DO INTERPOLED CONSTRUCTIONS DIFFER FROM ?STANDARD? MOTORS? http://kostov-motors.com/
The change is in several aspects: 1) The lack of interpoles creates a disbalance above 60-70V; the commutator is very hot while the armature/stator windings are cold. 2) This calls for few bars in the commutator so that the bars can be big to dissipate heat. 3) Few commutator bars call for a much longer armature so that torque/rpm can be reasonable. 4) The result is a long and heavy motor whose commutator is on the brink of melting but armature/stator windings stay uselessly cold. On the other hand, interpoles reduce brush arcing so that commutator temperature falls down. This allows a bigger bar count and shorter armature stack making the motor much lighter than its non-interpoled counterpart. Therefore for a comparable power, an interpoled motor has less weight (20-40%), bigger diameter but much shorter body and the ability to handle high voltage. Less weight means a cheaper motor and of course more range.
Motor with interpoles has more toque and can withstand more voltage compared to advancing brushes, so it's better in every way. Basically, much better power to weight which I've pointed out to be main advantage (interpoles + higher RPM - more power from same package).
Quote from kostov FAQ:
IS THERE ANY EMPIRICAL EVIDENCE ON THE EFFECT OF THE INTERPOLES? http://kostov-motors.com/
We have performed tests on an interpoled Kostov 9" 80V motor. One would think that 80V is relatively low and does not justify the use of interpoles. Indeed it may be so for low rpm, low amp forklift motors but the data shows this not to be true for EV conversion motors. For example most good EV motors have more than 4000rpm and 200A. The Kostov 9" 80V usually has collector temperature change of 120K in 60 minutes of work (up to 140K according to standard) at 280A. Removing the interpoles results in temperature change ot 157K in JUST 10 minutes. Advancing the brushes by 8/12 degrees improves the number to 147/141K but still in only 10 minutes. SHOULD THE BRUSHES OF AN INTERPOLED MOTOR BE ADVANCED? http://kostov-motors.com/
The interpoles create a magnetically neutral point whose position is independent of rotation direction, rpm, amps or voltage. The brushes are positioned exactly in this point. Advancing them will result in moving away from the neutral zone and will worsen commutation/arcing drastically. This, in turn, can have very bad consequences for the motor. HOW DO INTERPOLED CONSTRUCTIONS DIFFER FROM ?STANDARD? MOTORS? http://kostov-motors.com/
The change is in several aspects: 1) The lack of interpoles creates a disbalance above 60-70V; the commutator is very hot while the armature/stator windings are cold. 2) This calls for few bars in the commutator so that the bars can be big to dissipate heat. 3) Few commutator bars call for a much longer armature so that torque/rpm can be reasonable. 4) The result is a long and heavy motor whose commutator is on the brink of melting but armature/stator windings stay uselessly cold. On the other hand, interpoles reduce brush arcing so that commutator temperature falls down. This allows a bigger bar count and shorter armature stack making the motor much lighter than its non-interpoled counterpart. Therefore for a comparable power, an interpoled motor has less weight (20-40%), bigger diameter but much shorter body and the ability to handle high voltage. Less weight means a cheaper motor and of course more range.
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So what they are saying is that their motors are incorrectly designed so they have to use interpoles and accept the extra mass and reduced torque to make up for it?????
Glad I have got a Hitachi motor and not one of those badly designed Kostov things
Glad I have got a Hitachi motor and not one of those badly designed Kostov things
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171 Posts
Got them on the phone number listed on their contacts page, but you must call during working hours, which are 8-16 cet.
I guess they still provide support for ev motors, including selling new brushes, but I can't be sure. Although even if they don't, there shouldn't be any problems because you can have brushes made by some companies that specialize in that.
I guess they still provide support for ev motors, including selling new brushes, but I can't be sure. Although even if they don't, there shouldn't be any problems because you can have brushes made by some companies that specialize in that.
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171 Posts
WTF, they just uploaded new website, and EV motors category is still present??
And just a few days ago they told me that they've stopped producing them due to lack of interest?
http://kostov-motors.com/ev-motors/
...
And just a few days ago they told me that they've stopped producing them due to lack of interest?
http://kostov-motors.com/ev-motors/
...
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