[SCEV]

I'm just starting my conversion (86 Porsche 944 Turbo) and trying to figure out my parts list/budget. I'm having trouble deciding between the NetGain motors and Kostov motors. I'm planning to have around a 240V nominal pack (could change one way or the other depending on motor), and hoping for better than stock performance.

Attached is a spreadsheet I started putting together (you'll see lots more than the motor options, ignore the rest it's all just notional). Can someone verify the stats in the motor section? I can't figure out how to compare apples to apples with these, since the NetGain specs give torque and such at one voltage/amp and the Kostov at another.

Any other big pros/cons for the two brands (or specific models) anyone can share??

[somanywelps]

You want the voltage above 300V to compensate for sag under acceleration. Especially with smaller kwh packs.

[SCEV]

Originally Posted by somanywelps

You want the voltage above 300V to compensate for sag under acceleration. Especially with smaller kwh packs.

Only if I get a motor rated for 250ishV right? A NetGain motor rated for 170V should be fine with a pack voltage at nominal 240V...

[ruckus]

Regardless of which one you choose, I would upgrade the brushes to Helwig from the beginning (Netgain is already doing this). This will improve you temp, power, and longevity according to recent tests at EVTV.

Cheers

[Tesseract]

Originally Posted by ruckus

Why do your only options contain problematic and failure-prone brushes? Regardless of which one you choose. This will be the issue.

I would look at BLDC such as this before deciding.
http://www.greenstage.co.nz/PDFs/Scott_Drive_100.pdf
...

Uh-huh... Surely a Chinese motor controller will be the very paragon of reliability and performance in comparison...

Maybe this "Scott Drive" will be the exception that proves the rule, but as I pointed out in the thread about it, it's the same type of motor/controller as used in small computer fans - an application where low starting torque and high amplitude torque ripple (+/-15%) isn't an issue. In a traction drive, both of those downsides are objectionable, if not crippling.

I'd hold off on recommending this system until someone unbiased has actually tried it. On paper it doesn't look particularly impressive to me. $5500 for 80kW peak isn't any more powerful than the Curtis 1238 + AC-50, and it's actually more expensive than the latter system when purchased from a known good vendor like frodus here.

[ruckus]

Originally Posted by Tesseract

Uh-huh... Surely a Chinese motor controller will be the very paragon of reliability and performance in comparison...

I would actually recommend one of the MADE-IN-USA water-cooled brushless motors... Except, there are none for sale.

If you want air-cooled BLDC you can call Powertec. With typical american service they won't bother to call you back or even send you a price sheet with big numbers on it.

Originally Posted by Tesseract

Maybe this "Scott Drive" will be the exception that proves the rule, but as I pointed out, it's the same type of motor/controller as used in small computer fans - an application where low starting torque and high amplitude torque ripple (+/-15%) isn't an issue. In a traction drive, both of those downsides are objectionable, if not crippling.

Really? Then why has heavy industry shifted from brushed motors to BLDC? Again, Powertec and other BLDC documentation show very impressive starting torques so this argument seems a bit of a red herring.

Most electric motors don't have a torque problem, they have a hp problem. Especially inefficient air-cooled Brushed DC motors. Look at the specs, this motor weighs 54lbs LESS than the 11" yet is rated at 45+ hp continuous. Brushed motors just can't compete for long high-speed driving. How many OEMs use brushed motors? None. Hmmmm, wonder why?

Originally Posted by Tesseract

I'd hold off on recommending this system until someone unbiased has actually tried it. On paper it doesn't look particularly impressive to me. $5500 for 80kW peak isn't any more powerful than the Curtis 1238 + AC-50, and it's actually more expensive than the latter system when purchased from a known good vendor like frodus here.

It is called the Scott Drive 100 because the motor is rated at 100kw peak, not 80. They don't list a max wattage for the controller but it calculates to 200kva. According to the listed torque figures, the AC-50/Curtis is not in the same league. The "100" is the "derated" model. More power and voltage should be coming soon.

The Scott Drive system is currently installed and being used in several cars in NZ. Several thousand km and no problems reported. The controller is not Chinese, but made with quality in New Zealand.

I look forward to meeting you (I think your controllers are brilliant) at EVCCON where I will likely have a Scott Drive for display along with the "brushed" '37 Jaguar.

Cheers

[Yabert]

Originally Posted by SCEV

A NetGain motor rated for 170V should be fine with a pack voltage at nominal 240V...

Yes, but if you expect high performance you will need more than 170v (exept if you think about two motor).
From your first question, I was thinking that you only want to choose between Warp 11 HV and a Kostov Alpha.

Both motor will be impressive with proper battery pack.

Personnaly, I'm impress by the high efficiency of the Alpha (even at 500A). It's probably a good sign of what it can do at 1000A (or more).

But, the Warp 11HV have proof few time that it's a beast (Crodriver BMW, Valerun BMW)

[Tesseract]

Originally Posted by SCEV

Only if I get a motor rated for 250ishV right? A NetGain motor rated for 170V should be fine with a pack voltage at nominal 240V...

Yep - 240V is plenty of voltage to maintain a nice, flat power band with a NetGain advanced timing motor. You might want to run 300V+ if you choose one of the highest voltage Kostov motors, or the interpoled WarP-11HV, but then you won't want to push as much peak current through them (no free lunch - higher voltage tolerance generally means lower current tolerance).

Originally Posted by ruckus

I would actually recommend one of the MADE-IN-USA water-cooled brushless motors... Except, there are none for sale. ...

Au contraire... the Remy HVH250 is made in the USA, is liquid cooled and can be purchased retail from: http://vaxosystems.com/store/category/53-motors.aspx

Originally Posted by ruckus

It is called the Scott Drive 100 because the motor is rated at 100kw peak, not 80.

You might want to take a closer look at the PDF you linked to above. If you multiply the peak voltage and phase current ratings for the motor - even assuming that both are RMS (DC equivalent) values - that's still only 67kW of peak power (320V * 121A * 1.73).

NB - I didn't respond to the rest of your post because it was mostly you trying to prove AC is better and who am I to argue otherwise?

[ruckus]

Originally Posted by Tesseract

Au contraire... the Remy HVH250 is made in the USA, is liquid cooled and can be purchased retail from: http://vaxosystems.com/store/category/53-motors.aspx

Thanks for the link. Always happy to learn about something new.
...and only 3x the price for the same 100kw.

Originally Posted by Tesseract

You might want to take a closer look at the PDF you linked to above. If you multiply the peak voltage and phase current ratings for the motor - even assuming that both are RMS (DC equivalent) values - that's still only 67kW of peak power (320V * 121A * 1.73).

The ac-50 is 50hp and 110ftlbs Peak.
The Scott Drive is 100hp and 200ftlbs Peak. 2X the power seems pretty significant for that extra $900.

There is a big difference between "peak" and "rated". You are using the rated voltage and the rated amps and calling them peak. The Scott Drive motor can supposedly handle 540vdc (nominal) - I will be testing at even higher voltages with a "custom" Scott Drive controller.

Originally Posted by Tesseract

NB - I didn't respond to the rest of your post because it was mostly you trying to prove AC is better and who am I to argue otherwise?

Really? I didn't see that in my post. I am not a big fan of AC. It is more accurate to say that I am not blindly loyal to products that have a very high failure rate. Tim Cattellier is on his 3rd motor. Rickard lost 1 out of 3 so far. I am not getting even close to the rated hp. The stories of failure are growing daily. If controllers were blowing at this rate folks would quickly label them "worthless".

Nothing could be worse for the EV movement in the long run. Just as it is building steam with awesome batteries and controllers, the motors have become the new weak link. Perhaps with some tweaking (like Helwig brushes and high-power blowers) the brushed motors can stay on as an option. But to have SO many people pouring their savings and time into their project only to end up with an expensive fireworks display is unworkable.

I only seek a reliable and affordable drive system. Power and price is nice, but reliability is a MUST. I cannot at this time recommend a brushed motor to a person doing a conversion until these issues are resolved. I am sorry to bring such a dark cloud of reality into the open. But I believe it is better to deal with it now than to sweep it under the rug and have everybody hating EV's in 3 years.

[Batterypoweredtoad]

Rukus-you are on a strong apples to oranges streak. You keep saying the high failure rate of DC but what you are really seeing is the sudden emergence of cheap high power DC controllers. Of course the AC systems are not blowing up motors because all the controllers can manage is the motors rated continuous KW and maybe 2x that peak. A Soliton JR is rated to continuously push 4x the continuous capability of a K11 Alpha and that is Evnetics entry level controller. You put up baby AC systems and say they are more reliable than DC because people who abused their DC motors at 4x the power capability of your AC system blew the motor up.