# Kostov 11" 250V Wiring Construction



## major (Apr 4, 2008)

Old.DSMer said:


> I would hate to break something while trying to fix it when it wasn't originally broken


Why mess with it then? Kostov has a pretty good reputation as a quality motor builder. Chances are that the terminals are sufficient and consistent with robustness of the rest of the motor. I have never heard of a failure on a Kostov motor terminal. You may to do more harm than good. And if you alter it and have a problem there is little recourse. Should a problem occur with original equipment, Kostov is likely to help you. Just my opinions


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## Old.DSMer (May 18, 2012)

Thanks Major - just wanted to verify there wasn't some kind of drastic design oversight here. Not a whole lot of info on the terminal configurations that I could find. And after the problems I ran into regarding the RPM triggers (finger tight and coming loose), I wanted to be sure.

I'll swap the two terminals and make my bus bars. All good


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## Plamenator (Mar 6, 2009)

Hi,

This is not a "crimped brass fitting".
It is a brass bolt with a slot, then the copper wire is resistance welded to it. As Major hinted, there are many other spots that would melt much before the terminals cause problems in case of overload 
Of course have in mind that while motor may survive a single 1000A overload, it will probably not survive several overloads in a row. Also consider that thermal protection usually does not react on time to save you from too much time at 1000A...


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## steelneck (Apr 19, 2013)

Old.DSMer said:


> I thought I could just move the terminals and build bus bars shown in red - much easier to do.


That was a good idea.


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## Old.DSMer (May 18, 2012)

Plamenator said:


> Hi,
> 
> This is not a "crimped brass fitting".
> It is a brass bolt with a slot, then the copper wire is resistance welded to it. As Major hinted, there are many other spots that would melt much before the terminals cause problems in case of overload
> Of course have in mind that while motor may survive a single 1000A overload, it will probably not survive several overloads in a row. Also consider that thermal protection usually does not react on time to save you from too much time at 1000A...



Thank you Plamenator! I couldn't see any indication of a spot-weld, but resistance welding makes perfect sense now - my bad 

I was planning on setting up my Soliton1 similar to guys with the 11" Warps. So 1000A peak is not good --- what would you recommend as a motor max current? I won't be racing, but am looking for similar performance to the stock ICE. Which was in the range of 200 ft-lb (340 N-m). Based on the series-wound chart at 248V, I would extrapolate to somewhere near 700A. Would you agree? And (more importantly) is it advisable?




steelneck said:


> That was a good idea.


Thanks steelneck, I see no other way of easily connecting them in series without the risk of shorting the terminals. How have others done this???


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## Old.DSMer (May 18, 2012)

Can anyone recommend the max operating current for a K11-250? Is anyone running one in their daily driver?



Old.DSMer said:


> ... in the range of 200 ft-lb (340 N-m). Based on the series-wound chart at 248V, I would extrapolate to somewhere near 700A. Would you agree? And (more importantly) is it advisable?


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## ElectriCar (Jun 15, 2008)

Subscribing...I have the k11 192V model and am coupling it to a 700R4 automatic. I'm thinking of limiting it to around 700 just to be safe, but I have no solid reason in picking that number. I've already blown two armatures in my Advance 9 with the Soliton 1 and don't want to do it again!


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## piotrsko (Dec 9, 2007)

FWIW: On my K11-192 I ran about 100 hp. So at 170 volts battery sag, something like 450 amps for 2000 miles. New volt pack let's me run at 150 hp, but haven't pulled monster hill on way to work yet, sorting out recharge issues. At 3500 rpm motor is not hot to touch in summer desert heat. YMMV.


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## ElectriCar (Jun 15, 2008)

So you hold it at 450 amps for climbing hills? That's about what mine does climbing interstate hills in my area at 75-80, pulling 75kw at 162V. That's what I was doing last time I blew an armature. I was running around 75-80mph for about 10 miles, probably 6-7 minutes but only hit that many amps going up hill. 

What is your your maximum motor current setting? How often have you taken this motor above 500A? Ever hit 1000A? 

I did it a few times with the ADC9. I think current wise it wasn't a problem. No commutator damage. When it lets go, it seems as though a winding has broken loose from the commutator bars somewhere. I believe it's a torque twisting thus mechanical issue due to the massive current and torque generated.


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## piotrsko (Dec 9, 2007)

No, 450 ish amps pulling monster hill @50 mph 3500 rpm about 4 minutes. Sol1 setting at 150 kW motor max. Don't think I ever went over 600 motor amps. FLA pack wouldn't output that much at that point in trip. My typicals are about 250/275 @ 60mph, however need to run logger again with new pack as I think overall power went way up.


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## ElectriCar (Jun 15, 2008)

Wow just curious how many miles you have on this motor? Also do you have the factory brushes?


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## piotrsko (Dec 9, 2007)

1500 miles+/-. Factory brushes which reminds me I need to look at. I try to keep it within the kostov chart for duty cycles. Ie: 250 amps = 100% duty cycle


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## Old.DSMer (May 18, 2012)

piotrsko said:


> No, 450 ish amps pulling monster hill @50 mph 3500 rpm about 4 minutes.


WOW is right - what kind of temperature were you at after that sustained power draw?

Right now I've set up my motor at 220V and 500A. No problem pulling that in a 2nd gear flat road acceleration - and sustaining it through the start of 3rd gear. Only about 60 km/h. Maybe 4 seconds? I have not yet had my car on the freeway to test higher speed power draw. And I don't have my thermister hooked up for data logging yet. After some short test drives, the motor was barely warm - I am running a forced air cooling fan (4" bilge blower) right now as well.

Those settings produce some good acceleration, but not quite where I want to be - matching or exceeding the original ICE. I would need to crank it up to about 250V and 700A, but I'm not yet clear if this is safe/advisable???


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## ElectriCar (Jun 15, 2008)

So how many miles on the Talon? I know you've had it running a while now. Just read your build thread last night.  

The ADC9 I had in my S10 had good torque at 500A, much better around 800 but I'm scared to allow this motor that much juice. As much as I love that takeoff power, I really want to just drive the thing and not smoke it!

Re the heat buildup, motors like this with interpoles are supposed to run cooler than those that don't like the ADC9. Mine came with a blower but it appears to be a cheap blower.


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## Tesseract (Sep 27, 2008)

People have been asking this question for years, and the motor manufacturers generally dodge it. The blame is not entirely theirs, however, as this question is almost impossible to answer as it depends heavily on the environmental conditions, the past and future current vs. RPM vs. time conditions experienced by the motor, etc.

So let's start with one spec that is usually given for motors which is the S2-60, or "1 hour" rating, which is the current the motor can handle for 1 hour without any part - internal or external - exceeding the temperature rating of its insulation. For the Kostov K11-250, the S2-60 current is ~210A. 

Theoretically, you can use an equation for energy, I²t, to determine acceptable current at other timescales, but the problem with this equation is that motors have much more complicated thermal characteristics than, say, a straight conductor in free air. What happens, essentially, is that I²t underestimates the current rating at timescales longer than 1 hour (it actually doesn't go much lower than the S2-60 rating) and progressively overestimates the current rating at timescales shorter than 1 hour. In other words, you can't run a K11-250 at ~420A for 15 minutes, not without cooking the armature but good, and at 840A the brushes or commutator will give up the ghost long before the 3.75 minute mark.

So what max current is safe? Well, that depends on how close an eye you want to keep on your motor. In essence, you can trade security/convenience for performance. My suggestions, which I do not warrant and will not be responsible for their application, are to set max motor current to 600A if you don't want to worry too much about your K11-250. You can bump that up to 700A if you want a bit more performance and have the discipline to limit time at that current to no more than 15-20 seconds out of every minute or so (and running at the S2-60 current or less and at 2krpm or higher for the rest of the time). Only if you actively monitor motor current should you run at higher than 750A and I strongly suggest installing an optical thermometer aimed at one of the brushes as well.


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## ElectriCar (Jun 15, 2008)

Thanks Tes.


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## Batterypoweredtoad (Feb 5, 2008)

There was a thread about the K11 Alpha where planetmotor from Kostov gave some good information about the Amp time tolerances for the Alpha at higher Amp levels. I'm sorry I don't have a specific thread link but my tablet and the forum search feature were not playing well together. If someone else could find it it would be helpful to this thread.


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## Old.DSMer (May 18, 2012)

Tesseract said:


> So what max current is safe? WellYou can bump that up to 700A if you want a bit more performance and have the discipline to limit time at that current to no more than 15-20 seconds out of every minute or so (and running at the S2-60 current or less and at 2krpm or higher for the rest of the time). Only if you actively monitor motor current should you run at higher than 750A and I strongly suggest installing an optical thermometer aimed at one of the brushes as well.


Thank you Tesseract for the detailed explanation. I will not hold you liable for any statements 

The optical thermometer is a neat idea. I will investigate that further.


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## Old.DSMer (May 18, 2012)

ElectriCar said:


> So how many miles on the Talon? I know you've had it running a while now. Just read your build thread last night.
> 
> The ADC9 I had in my S10 had good torque at 500A, much better around 800 but I'm scared to allow this motor that much juice. As much as I love that takeoff power, I really want to just drive the thing and not smoke it!
> 
> Re the heat buildup, motors like this with interpoles are supposed to run cooler than those that don't like the ADC9. Mine came with a blower but it appears to be a cheap blower.


Originally, I only "tested" about 15km before my Tsubaki taper lock failed. Then my EMW charger failed unexpectedly. I replaced the coupler with a Fenner and fixed the charger.

So I test drove about another 16km last night. Never got above 60km/h since I stuck to side roads that were not busy. Motor was fairly warm to the touch when I got home (lots of stop-starts at 500A).

Things seem to be running good so far (knock on wood)!


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## Old.DSMer (May 18, 2012)

Batterypoweredtoad said:


> There was a thread about the K11 Alpha where planetmotor from Kostov gave some good information about the Amp time tolerances for the Alpha at higher Amp levels. I'm sorry I don't have a specific thread link but my tablet and the forum search feature were not playing well together. If someone else could find it it would be helpful to this thread.


Thanks, I will do more searching when I have time.


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## Tesseract (Sep 27, 2008)

Old.DSMer said:


> Thank you Tesseract for the detailed explanation. I will not hold you liable for any statements
> 
> The optical thermometer is a neat idea. I will investigate that further.


IIRC, we used the 0-5V version of the OS136 optical thermometer from omega.com. We drilled a hole in the gravel guard around the brush area so that it would be aimed at one of the brush assemblies and then connected it to one of the aux inputs on a Soliton, but you could use a digital multimeter, just work out the conversion of voltage to temperature ahead of time then go for a drive (it should go without saying that you probably should have a passenger do the monitoring... )


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## Old.DSMer (May 18, 2012)

Tesseract said:


> IIRC, we used the 0-5V version of the OS136 optical thermometer from omega.com.


Looks good. I'd probably permanently mount it and wire a drive circuit for one of the gauges.

I'm going to keep things at 250V and 500A for now. My right foot has a mind of its own and I don't want to risk over stressing the motor with no instrumentation


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## piotrsko (Dec 9, 2007)

http://www.diyelectriccar.com/forums/showthread.php?t=70557. Page 2 post # 11.

Looks like for me 450 ish amps @4 min is just at the ragged edge of motor meltdown. Might have to back it off a wee bit. YMMV.

AND, no, I can't give you a meaningful temp at the top of monster hill. Kostov thermistor is tied into idiot water temp gauge, best guess is about 175-200 f based on needle position.


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## Old.DSMer (May 18, 2012)

piotrsko said:


> http://www.diyelectriccar.com/forums/showthread.php?t=70557. Page 2 post # 11.
> 
> Looks like for me 450 ish amps @4 min is just at the ragged edge of motor meltdown.


Sorry, I do not see the correlation with 4 min. Can someone explain how that is extrapolated from the S2-60 data?

If I increase to 680A, that would range from 0-4000 RPM for a duration of about 6 seconds on flat ground. On a hill, how would I calculate the time, say, at 3000 RPM. Which is about 130V?

I have not yet received my thermocouples for testing motor temps. I'm hoping to get a differential between case and brushes under different loads.


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## piotrsko (Dec 9, 2007)

Data graph doesn't go there. Plamenator said 500 amps for about 4 min on a 11-250, I believe in series configuration. That graph hints 520 max amps. Mine is only 475 max amps. SWAG on my part.


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## Old.DSMer (May 18, 2012)

piotrsko said:


> Data graph doesn't go there. Plamenator said 500 amps for about 4 min on a 11-250, I believe in series configuration. That graph hints 520 max amps. Mine is only 475 max amps. SWAG on my part.


It seems different brands of motors react differently to overload magnitudes and durations. I'm going to keep things "conservative" and follow Tes's advice on monitoring temps.


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## piotrsko (Dec 9, 2007)

Just be aware of a serious time lag between overtemp event and reporting of said event. I would set my alarms perhaps 100 to 150 degrees low. My space shuttle experiences suggest up to 30 seconds late reporting oops events with most sensor systems.

Your kostov doesnt have the brush temp click switch? Makes an excelent idiot light.


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## Old.DSMer (May 18, 2012)

piotrsko said:


> Just be aware of a serious time lag between overtemp event and reporting of said event. I would set my alarms perhaps 100 to 150 degrees low. My space shuttle experiences suggest up to 30 seconds late reporting oops events with most sensor systems.
> 
> Your kostov doesnt have the brush temp click switch? Makes an excelent idiot light.


Agreed, especially depending on location. My motor has a non-standard PTC thermister. Annoying since most circuits use a NTC. So I ordered a hand held unit with dual inputs using K-type. Cheap and quick for some data collection and I will review something more detailed and permanent in the future.


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## Old.DSMer (May 18, 2012)

major said:


> .... I have never heard of a failure on a Kostov motor terminal....


Not sure I would call this a specific "terminal" failure....but the top middle terminal did disappear. For those watching this thread, more info here.


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## major (Apr 4, 2008)

Old.DSMer said:


> Not sure I would call this a specific "terminal" failure....but the top middle terminal did disappear. For those watching this thread, more info here.


Yes, I saw this. I was wondering why you didn't make a warranty claim to Kostov


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## Old.DSMer (May 18, 2012)

major said:


> Yes, I saw this. I was wondering why you didn't make a warranty claim to Kostov


We are currently working through the repairs outside the forum. I know others are running a similar setup and I wanted to post up the info (just haven't had time till now). Plamenator has been very helpful on the technical side. Very fast response and kudos to him for his tech support. Not sure how the costs will roll out yet...


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## Old.DSMer (May 18, 2012)

A little update is posted 
here.

Not back on the road yet, but progress has been made.


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