As we approach the summer solstice, I’m inspired to explore new and untapped areas of the realm of long boring technical videos. I think we’ve reached some sort of zenith this particular week.
The immediate object of this week’s video is another contest finalist, Alex Viera, who arrived to plead his case before EVTV viewers. Alex lives in Colorado Springs and is a musician with the U.S. Air Force – an oboe player no less. And he has a vision of populating the state with 4WD electric Suburus. He hopes to develop a conversion business by his retirement date in about 7 years. He seeks your vote in the “Build Your Dream” EV contest which is turning into quite a horserace. You can see the latest and vote here: http://www.projectooc.com/evtv/finalists.php
Mike Picard had jumped out to an early lead, but Brandon Hollinger has overtaken him. Brandon is another musician who did a superlative job of converting a Saab 96 to electric drive. He’s actually got quite a knack for garnering press attention to the concept of vehicle conversion. Time Video recently did a very interesting video piece on him which I thought was particularly well done.
I actually would have liked to include this in our next episode, but TIme being big ugly and stupid is of course impossible to even talk to about these things.
Back to big, ugly and stupid. The rest of our video this week is me attempting an explanation of the Netgain Warp 11 HV.
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Aside from the pernicious Alzheimer’s problem and my smoker’s cough, my onscreen personnae has another little problem that I simply deal with better in writing. That is a wide scope of audience. Some of our viewers DESIGN electric motors. Some of our viewers REALLY design electric motors at the highest and most modern levels. And some of our viewers still don’t quite get the Ohm’s law thing.
And we have everything in between. You don’t really need to be an electronics design engineer to VERY successfully build an excellent running and beautiful electric car. Ultimately, a motor is a motor is a motor and they have three or four connections with plenty of sample connection diagrams available. The basics are pretty simple = hook it up to a controller, press throttle pedal, and magically they convert battery capacity into forward motion. They are what makes you “go”.
But not all motors are created equal. And selecting the right type for any particular car is of course a design choice that has consequences and results in the final car. A greater understanding is always a good thing.
But I’m a little trapped between my vague understanding of how some of these things work, the unfortunate terminology engineers inevitable choose and generally choose poorly, and the understanding of a broader audience. In real time, I’m constantly groping for words that would avoid criticism from the learned for misuse or wrong use of terms, while actually communicating the concept to humanoids not of the priesthood.
Pity poor me – no. Actually that’s been the central issue of most of my adult life and I do it well enough, but more easily in writing with the luxury of review and revision than standing there actually doing it in front of a camera. It’s been good to me in many ways. The pathological inability of engineers to read, write, or speak in English has provided me a pretty nice career. I shouldn’t complain.
In selecting a motor for our Aptima Motors eCobra design, George Hamstra naturally enough thought one of his motors would serve admirably for the project. I demurred somewhat noting that we were doing his motor to death in the Cadillac Elescalade, and the Speedster Redux this year, and that I was looking for something a bit exotic and new to talk about. Of course, the exotic and new also seems to be actually unavailable most of the time, so I was spending a lot of time chasing down interesting things that had 16 week delivery times and huge price tags (EVO) or were really just web fantasies a long ways from any fruition as a product (Remy and a host of others). The web has so many pretty pictures of so many beautiful things, and such a thinly grained reality component as to hardware you can actually make show up in your driveway.
His main suggestion was the Netgain Warp 11HV. Now Netgain is most known for the very popular Warp 9 which we’ve used successfully twice. Dismissed by the cogniscetti as a “fork lift motor” these motors are actually quite durable, and capable of 200kw power levels for a tiny fraction of the cost of a more modern BLDC IPM motor. The Warp 9 is undoubtedly the most popular mount for electric vehicle conversions.
The Warp 11 is the same only bigger. So the 11HV has some magic dust to make it do voltages higher than the 170v limit we normally recommend on one of these horses. With the Hellwig brushes rather raising that to 200v, I guess I don’t get it.
The main advantage of the 11 inch, is a longer torque arm. For the same voltage and current, you’ll get more torque from an 11 inch than a 9 inch simply because the force of interaction of the fields happens an inch further from the shaft – more leverage so to speak.
I had heard that the 11HV actually used the rotor out of a Warp 9 – giving up that advantage rather. So I was underwhelmed. A Warp11 without the advantage of the Warp 11, but could do a few volts higher?
Not precisely. And therein lies a tale. This Warp 11HV has about as much to do with a Warp 9 or Warp 11 as it does with a cake mixer motor. George’s preoccupation with the “Warp brand” has led him down a path where I think most of the universe misses the part about this being a COMPLETELY DIFFERENT MOTOR in all respects. Naming it a Warp 11HV confuses the issue. Painting it red doesn’t help.
And in truth, George is kind of careful about his product reputation. He notes a 0.004 return rate on his products and he’s justifiably proud of that. The 11HV is kind of a new and somewhat avante guarde design in his line. And he’s watching the few installations out there kind of carefully before promoting the motor widely. So it’s kind of not been precisely a SECRET, but not exactly pushed on the marketing front either until they see how it does.
And subsequent to his suggestion and after talking with several who have actually used them, in the words of EVBlue’s Wayne Alexander, it seems this motor causes a car to “go like a scalded dog.” Not intimate with deep Kansas vernacular, I’m assuming this means “with all due haste appropriate.”
The motor actually harkens back to an older General Electric design using interpoles to ameliorate the armature reaction and thus reduce arcing at higher voltages – in turn allowing the use of higher voltages at load and so higher power without damage. To study up on that, I returned to the Hawkins Electrical Guide.
Nehemia Hawkins was something of an icon to technical writers. He established a publishing empire on the basic premise of explaining the principles of electricity and its applications. Most know of him through the Audel’s series of guidebooks such as the Audel’s Radiomen’s Guide of 1934. But he did do a 10 volume opus under his own name in 1917. Today, you can look far and wide for a description of inductors, motors, alternators, and so forth before you find one with an illustration that does not look a little archaic. They were all stolen from this heavily illustrated encyclopedia. No one has really ever bothered to do better graphics on these mature topics. And so you see the same black ink sketch of a dynamo over and over.
Hawkins Electrical Guide – Volume I – Electricity and Its Applications is available for download from Google books and of course has been in the public domain for many years. Google has made a copy of this available in PDF format and in an utterly BIZARRE take on copyright law, claims some sort of vague right from the expense of scanning it and has made the incredible leap that they can then deny you any commercial use of it. The Internet just gets curioser and curioser. So don’t use it for anything useful, and for God’s sake don’t change the watermark or Google will do something….they were a little vague as to what….
In any event, I highly recommend the tome for those seeking a deeper understanding.
To describe what the 11HV REALLY does, I had to start with the Universe and all things electric and work my way down to the basic question of what causes brush arcing and why Netgain has an “advance” of 12 degrees on the brushes as shipped from the factory.
The short answer is that the 11HV can do up to 288v because of its’ Interpoles. The bearings have a 14,000 rpm limitation and the commutator about 9000. And so in theory you can put 2000 amps into a motor at 288volts and make useful power up to 9000 rpm using existing off the shelf components. That’s about 576kw or 772HP input.
Now if you do that, you’re going to blow this motor up into several hundred very high velocity pieces. So do it at least 100 yards away from me. But it does mean you can do considerably higher power at higher rpms than you can with a Warp 11 or any other Warp motor from Netgain. You do lose about 10% torque at the very bottom, but gain all the way up. We’re hoping to peak in the 4000’s somewhere with this motor at 240v.
We were looking at Zilla controllers for this project. Rich Rudman of Manzanita Micro, being his usual charming self and still raging over the damage we’ve done to his BMS business, managed to talk me out of it. Ostensibly they are going to produce the Zilla. As there are still victims of the James Morrison fiasco who have paid for the LAST great Zilla partnership in Otmar’s ongoing search for a date to the prom, still without receiving their Zilla’s, I guess I’m a little gun shy. We’re just not going to deal with this controller. It just doesn’t exist. I’ve got two on the shelf but we’re just never going to use them because I cannot in good faith recommend you try to buy one. And frankly, the technology has marched on anyway with newer and better semiconductor components. By the time they get all that sorted out, it will largely be irrelevant with newer and stronger products readily available and at a fraction of the price.
Irony of ALL ironies, George Hamstra actually had done a deal with Otmar several years ago to produce the Zilla controller. He didn’t even know the deal was dead until Otmar posted a bizarre notice on his web site that it had “fallen through”. He never even bothered to call George and tell him it had fallen through and nobody knows yet why or how it had “fallen through.” The Zilla could have been in production for years…
Anyway, we’re still looking at controllers for the eCobra. Meanwhile, we received kind of a transmission template with our Tremec TKO-600 and the hole in the middle is an exact match for the bezel on the Netgain Warp 11HV. What an omen. The adapter becomes trivial. We just hand the template to our machinist along with the magic number – distance to the flywheel face, and we should have an adapter and coupler.
It will be interesting to see viewer reaction to my hour long treatise on this topic. I’ve cringed a few times in the past over our “watching paint dry” battery episodes and they have had more views than any other. Perhaps my sense of what makes good video is not as sharp as I think.
Or maybe they’re not watching for just my jokes and taste in exotic alcohols….Our thanks to Alex Viera for the excellent bottle of Stranahan’s Colorado Whisky.