# Kostov vs Siemens



## WinterT (May 22, 2014)

I've been creeping on this site for quite some time and will hopefully be starting up a project this year. I'll be picking up MG Midget roller soon (1700lbs). Specking out this build all while trying to balance quality components with my inherent desire to be cheap has been difficult to say the least and has become a full time job. That being said I still love the idea and am going to go forward. 

So herein lies my question, if one were to compare a Kostov 13 (65kW/138Nm) to a Siemens 1PV5135-4WS14 (67kW/160Nm), on paper the Siemens wins but which is actually better? I've seen some posts indicating that the numbers are not accurate but I haven't seen much in real world numbers or people actually using either motor. Price to power/torque in both is impressive (on paper). The Kostov is DC whereas the Siemens is AC. Does anyone have first hand knowledge on either? Or any recommendations that can match the numbers on these two? Thanks in advance

Kostov 13:
Kostov Motors
Siemens 1PV5135-4WS14
EVTV Motor Verks Store: 1 Siemens 1PV5135-4WS14 AC Induction Motor, Motors and Controllers, 1PV5135

Planned build:
1969 MG Midget
Range: 100 miles
Max speed: ~90mph
Direct Drive (no transmission) 
Motor: Undecided
Controller: Based on motor
Battery: 5-6 Tesla Model S modules (26-31.2kWh)
Vehicle Weight: 2,500lb probable, 3,500lb worst case


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## ElectriCar (Jun 15, 2008)

I have a Kostov 11" and totally not happy with it. It overheats on any highway driving, seems to lack torque as well. I had a DC9 before which seemed to have more torque and never ran hot. I've even added a large blower to the thing and it still smells after a 10 mile drive at highway speeds. And I'm talking 60-70mph. The DC9 I could run harder and it didn't overheat. IDK why this thing is screwed up but I regret buying it.


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## brian_ (Feb 7, 2017)

ElectriCar said:


> I have a Kostov 11" and totally not happy with it. It overheats on any highway driving, seems to lack torque as well. I had a DC9 before which seemed to have more torque and never ran hot. I've even added a large blower to the thing and it still smells after a 10 mile drive at highway speeds. And I'm talking 60-70mph. The DC9 I could run harder and it didn't overheat. IDK why this thing is screwed up but I regret buying it.


As discussed in the thread on this issue, the motor is probably not the problem, and the issue says little if anything about the Kostov motor in comparison to the previous motor (also a brushed series motor).


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## WinterT (May 22, 2014)

ElectriCar said:


> I have a Kostov 11" and totally not happy with it. It overheats on any highway driving, seems to lack torque as well. I had a DC9 before which seemed to have more torque and never ran hot. I've even added a large blower to the thing and it still smells after a 10 mile drive at highway speeds. And I'm talking 60-70mph. The DC9 I could run harder and it didn't overheat. IDK why this thing is screwed up but I regret buying it.


After looking at everything I think I've settled on using the Siemens, one reason being the price the second being I have seen at least 1-2 real world examples of it being utilized in a build. Sorry to hear your setup is giving you troubles though. I took a look at the thread that brian_ referenced and it does look like the addition of an auto trans, alternator, and AC might cause a heavier draw imo. Have you considered disconnecting the alternator and AC to see what the difference might be? Obviously you can't just switch back to a manual so the impact of that can't be confirmed but it might help sorting out/confirming the issue.


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## ElectriCar (Jun 15, 2008)

WinterT said:


> After looking at everything I think I've settled on using the Siemens, one reason being the price the second being I have seen at least 1-2 real world examples of it being utilized in a build. Sorry to hear your setup is giving you troubles though. I took a look at the thread that brian_ referenced and it does look like the addition of an auto trans, alternator, and AC might cause a heavier draw imo. Have you considered disconnecting the alternator and AC to see what the difference might be? Obviously you can't just switch back to a manual so the impact of that can't be confirmed but it might help sorting out/confirming the issue.


The AC isn't used much but when it is it doesn't draw very much. The alternator is a fairly light load also. 

Today I spoke with a guy at a rebuild shop. We looked at their drawings and finally he suggested I might try rewiring it to parallel field with stead of series.

So I did that. It seems to be much better as the idle kw is lower and the same thing driving. I drove it up the interstate a bit at 60-70mph and the wh/mile was indicating about 550. I'll know more after another drive or two.

Sure the auto takes more power as you have a little slippage, but how much? I read on here a few years back how much it adds but I don't recall the data. I do recall that an AC takes about 5hp but I've not verified that.

I just want to drive it and for it to be reliable. The Advance 9 is a great little motor but it's not sexy fast! 😆


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## brian_ (Feb 7, 2017)

ElectriCar said:


> Sure the auto takes more power as you have a little slippage, but how much?


Roughly 10% of the power put through a torque converter is lost in the best case, and 100% at idle. The hydraulic pump needed to operate the transmission's clutches burns some power, too.


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## ElectriCar (Jun 15, 2008)

The 700R4 has a lockup torque converter so the losses once moving aren't much, just the pump mainly I would think.


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## DansEVhobby (Jun 13, 2021)

ElectriCar said:


> The AC isn't used much but when it is it doesn't draw very much. The alternator is a fairly light load also.
> 
> Today I spoke with a guy at a rebuild shop. We looked at their drawings and finally he suggested I might try rewiring it to parallel field with stead of series.
> 
> ...


I'm an absolute beginner at this but just a suggestion:
Your truck is old, with a solid heavy frame. It's a very heavy truck for an EV. Maybe you could fit a much bigger motor in than the 11, go for even more weight since ur truck can handle it and needs more power. There's guys selling DC motors on ebay right now for like 500 bucks that weigh 250+ pounds. Which is still lighter than the motor that came out of ur truck.


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