# What's holding the EV drag racers back?



## toddshotrods (Feb 10, 2009)

I'll back this post with more specifics and detailed info as I can, but I wanted to (hopefully) get the discussion going. I don't mean to belittle the accomplishments of any of the people who have successfully accomplished any type of performance with their EVs, my questions are more about the potential of the format.


Wayland's White Zombie runs mid 11s at around 2000 lbs, with 772lb-ft of torque and 240+hp.
Willmon's Crazy Horse Pinto runs mid 12s with nearly 1300lb-ft of torque and over 300hp.
I think Wilde's Maniac Mazda falls in the same basic territory.
On the other hand there's the KillaCycle drag bike and the Current Eliminator dragster that are both in the 7s at 170+mph, and nearly 160mph, respectively.
My question is what is causing the gap in performance? According to traditional drag racing practice, and EV/ICE power comparison rates, those first three cars should be running low-9 and possibly high-8 second quarter-mile ETs, at the least. With 700-1000lb-ft of torque and 750-1000hp (converted with 3:1 ratio from EVs), a heavy steel bodied car (say a 3500+lb 69 Chevelle) would post really impressive numbers far beyond what the EVs are doing.

The main difference I see in the first three cars, and the dedicated drag racers, is chassis. What really doesn't make sense is how they are running these cars all-out with stock chassis. In an ICE car similar to the three mentioned, 700+lb-ft would twist the car like uncooked pretzel dough. We always tell people that put monster IC engines in stock chassis cars that if they ever really launch it it'll come back with one of the front wheels hanging in the air, like a dog with a hurt paw.

If electric motors give you full torque at 0rpm, and these guys have so much of it, why aren't they posting better ETs and/or mangling their cars?


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## major (Apr 4, 2008)

toddshotrods said:


> If electric motors give you full torque at 0rpm, and these guys have so much of it, why aren't they posting better ETs and/or mangling their cars?


Hey todd,

A couple of things come to mind. The electrics run direct drive. No tranny or torque converter like the gassers. So on the launch, do they really have more torque at the rear end than an engine, torque converter and 1st gear?

And it looks to me like the electric guys see declining power about half way down the strip whereas the gassers are getting into their power band there.

Been to a couple of electric drags, but never ran one or built one. Just my opinions.

major


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## toddshotrods (Feb 10, 2009)

Thanks Major. Declining power around half-track would explain a lot. I've always found it interesting to see the numbers that serious drag cars post after breaking or shutting down at half track.

Previous versions of the Current Eliminator dragster originally had a 4spd transmission, but they eventually went to direct drive. That only seems to be an issue when you don't have enough battery/controller power to deliver. At least two of the three street cars mentioned have massive power, built motors, and Zillas. The Mazda proably does too, I just can't recall it's powertrain configuration at the moment.

They launch hard enough to waste Vipers, etc, off the line, so I am more inclined to believe you're onto something with the declining power.


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## CroDriver (Jan 8, 2009)

The biggest problem: There are to few Zillas! 

Btw. If anyone has a HV Zilla, contanct me!!


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## metallover (Aug 6, 2008)

I would say the batteries are holding back technology a little, but you can put a band-aid on that with a huge capacitor bank. Todays batteries don't provide too much "punch". The best lithium-polymer batteries in RC planes and cars can provide 35c+ constant discharge, but the biggest cells they make top off at about 5000mah. A123 cells are durable, but don't have much "punch" compared to lithium polymer packs and don't hold a high voltage under load. I bet in 10-15 years a batter battery will come out boosting the performance to stupidity, but battery technology will always be evolving so keep an eye out.

Controllers and motors could use some work too, but the thing is there aren't enough companies to create any huge competition. If there were competition, the motors and controllers (like the zilla) would be more commonplace and cheaper.


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## IamIan (Mar 29, 2009)

I suspect Energy storage in the batteries is the biggest hold back ... not just for range in Kwh/kg ... but also in speed for kW/kg.

Capacitors can give large punches off the line... but they just don't have the energy density in order to maintain that energy expenditure rate... and in a very short period of time the power output drops quickly ... Batteries have better energy density ... but they don't have the capacitors power density.




> Today, commercial ultracapacitors have specific energy densities over 5 Wh/kg and specific power densities of up to 20 kW/kg.




This still puts Capacitors significantly above even the best instant pulse from the most advanced A123 battery which can put out up to ~5kw/kg.

For example and I am sure there are tons of others.

The SSC Ultimate Aero produces a peak power of 882.2kW... and peak torque of 1,094 Ft Lbs.

While it is producing that level of power and torque it will burn up its 32 Gallon tank of gasoline in ~7.5 Minutes ( SSC claimed this on an interview on Jay's Garage ) ... or ~4.3 Gallons per minute ... 0.0711 Gallons per Second.

Even if we forget about the horribly low % of efficiency of the gasoline engine that actually gets used... 882.2kW for ~7.5 Minutes is ~110 kWh of energy... or ~14 kWh per Minute ... or ~0.245 kWh per second.

In order to produce 882.2kW peak power modern capacitors at ~20kw/kg would need ~44kg ( ~96.8 Lbs ) of mass ... Modern Advanced batteries like A123 at ~5kw/kg would need ~177kg ( ~388 Lbs ) .... compared to burning just 0.0711 Gallons of gasoline in order to get that peak level of power for 1 Second duration and would only weigh ( at 6.073 lb per gallon ) ... ~0.432 Lbs ( ~0.196 kg ).

In just 1 Minute the ~4.3 Gallons of gasoline would only weigh ~26 Lbs... there is no battery out there that will give you ~14 Kwh of energy in ~26 Lbs ( ~11.87 kg ).... even EEStor does not claim to be able to produce that much in that little space or weight... and they are a bunch of crazy people.

Liquid fuels like Gasoline ... just have a crazy density of both power and energy per kg or L.... ~36 kwh/Gal or ~9.6kWh/L... ~5.9kwh/lb or ~13kwh/kg... those energy and power densities ... are just crazy to try and compete with in a modern battery... Even the best batteries in the future I do not think will ever have greater energy / power densities than Liquid fuels like Gasoline do.

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The only thing I see eventually giving EVs an edge ... is the efficiency ... the amount of waste energy for the use of combustion engines is crazy high compared to EVs and electric motors... this massively better efficiency for EVs and electric motors means longer ranges per unit of energy used ... and far less heat generated per unit of energy used.

Eventually the massive amounts of waste heat generated end up being a show stopper for the lower efficiency options... the SSC Ultimate Aero have a very extensive and complicated cooling system to keep the waste heat generated from destroying the engine... while a EV version that could produce as much kW of power would have massive weight penalty from the battery compared to gasoline ... it would produce massively less waste heat.


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## toddshotrods (Feb 10, 2009)

After looking at it more carefully, I don't think the cars are having a problem getting off the line. I forgot that unibody vehicles have much more torsional stiffness than the old body-on-frame vehicles that were known for getting all bent out of shape. Another thing I didn't take into account was what kind of roll cage they may have. The solution to twisting an old Camaro, Mustang, etc., was to add enough roll cage to handle the torque. Starting off with a unibody and adding even a four-point bar might be enough to keep things where they're supposed to be.

I also went back and look at the specs. White Zombie is launching on 215/60R14 drag radials - there's no way he's going to twist the chassis with that. Maniac Mazda uses 11x28x15 wrinkle walls, has pulled the front wheels significantly, and now uses wheelie bars. Being a unibody sports car, I suspect it is quite stiff, torsionally. Both cars have made more than one pass under 11.50, so they probably have cages (typical sanctioning rules).

The fact that they launch hard was never a question. I was curious how they were doing it without twisting the car. The way the Mazda runs away from that Viper off the line I would expect at least a low-10/high-9 pass, but major's theory of declining power makes sense. Leave like a serious drag car, but finish like a street car. It also answers my question about why the ET's are so low, for the power they have.

Actually, I am encouraged by this discussion. If the key is a good chassis and low weight, e.g. KillaCycle (653lbs) and Current Eliminator (1175lbs), I am on the right track. I plan to come in well under 2000lbs with lithium, and my chassis is being purpose-built for racing. I should be able to put what power I can generate on the track efficiently, and maintain enough momentum to post times somewhere in between the all-out drag racers and the street cars. My SepEx motor/controller setup may also allow me to keep the motor in the meat of the curve longer - at the cost of a few motors to figure it all out!


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## Batterypoweredtoad (Feb 5, 2008)

Total power and gearing. 600ft lbs of torque sounds great, but combined with 150hp it turns into just pretty good. Combine that with a single gear and a powerband that ends halfway down the track and you are screwed. IIRC the Maniac Mazda did use a powerglide-but if he is pulling massive wheelstands maybe his gearing gives him even MORE torque off of the line, but isn't tall enough to make up for the weak back half of the track performance?


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## JRP3 (Mar 7, 2008)

I'd also take a close look at the batteries each is using. Killacycle's A123 can do over 40C with preheating, Current Eliminator's Altairnano's are probably capable of similar output. I don't know what the others are using but if it's not one of those two they are probably battery limited.


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## toddshotrods (Feb 10, 2009)

Batterypoweredtoad said:


> ...IIRC the Maniac Mazda did use a powerglide-but if he is pulling massive wheelstands maybe his gearing gives him even MORE torque off of the line, but isn't tall enough to make up for the weak back half of the track performance?


You remember correctly - he uses a glide.

Maybe this is my fault, since I started this, but you guys are being kind of hard on them. I am really impressed with what these guys have accomplished. White Zombie and Maniac Mazda are both knocking on the door of 10 second ETs. They wouldn't get beat very often by comparable ICE cars. Even if the performance is declining after half track, the fact that they can obliterate a 400-500hp modern cars with their 1/8th mile performance is an awesome achievement.

I didn't mean for this thread to bash their accomplishments. I just wanted to see what seemed to be limiting them. You can't argue that they are not producing much/enough torque because they all basically slingshot off the line. It takes torque to do that. My two questions together seem to have created the idea that something is wrong on the bottom end. When I asked why the cars aren't twisting I wasn't implying that the torque wasn't really there. I was recognizing the fact that there is at least enough of it to do damage. I wanted to know why the effects of that torque aren't more visible.

I did look at the batteries JRP3. You have a valid point, but I think the overall setup is just as important. White Zombie dropped .4sec and gained 5mph in the quarter mile(to 11.466 @ 114.08), and .6sec improvement in 0-60mph with (A123) lithium in place of the lead. Significant but a heavy price for the gains. Maniac Mazda has a best time of 11.202 @ 108mph with a total of 216 volts of lead batteries(Johnson Controls / Inspira AGM)! He's quicker but slower - that's due to a better chassis setup (mazda triagulated 4-link vs leafs?) and better traction.

Until battery/controller/motor technology makes a significant leap I think finding a way to take advantage of the instant-on torque is the key.


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## 2cycle (Jul 2, 2009)

I'm new to the EV world but find lots of promise with it. I'm an ICE expert by trade, don't shoot me. We build and race lots of things from cars to snowmobiles. The only motor sport I've come across that needs big torque over the high rpm HP is tractor pulling and even they are getting pretty big HP numbers now. Lots of torque does nothing in the world of going fast, lots of hp and transmissions works lots better. Unless you have 8000 lb/ft of torque then a single speed and slipper clutch works fine. 
Drag racing with 772 lb/ft of TRQ and 240hp running direct drive is equal to that same weight vehicle with 260 lb/ft of TRQ and 260 hp with a flat long pulling power curve and a drag racing 4 speed tranny. 
I think for drag racing I would stick to a drag car tranny with a power interrupt during shifts like the ICE setups use and build an electric powerplant that makes power between 3000 and 8000 rpm. If it can't maintain a flat power curve to around 8000 rpm keep looking for a motor that does. We always try to hit our peak hp in top gear as we cross the finish line, not half way down the track like people suspect is happening to the EV racers.
I'm planning an EV build right now but haven't found any setup efficient enough. When we figure efficiency we count power to weight as being very important. EV's have very bad efficiency when it comes to this. To give you an idea of what we need is around 400 hp at 7000 to 9000 rpm and all included weight to be under 180 lbs. This is our current drag racer powerplant hp and weight. I keep looking but until the batteries get much better I can't see it happening.
I was hoping the technology was already here to use large capacitors to give huge amounts of power instantly, kind of like how we use nitrous oxide for instant power for short bursts. I need to keep learning about what's available.


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## toddshotrods (Feb 10, 2009)

That's why I was concerned the language in this thread was becoming too strong. I may screw this up (I'm still an EV novice as well) but there is a conversion rate for electric motor horsepower. It's stated that 30hp in an electric motor can do the work of 90hp in an ICE. The reason is the electric motor is rated for continuous (I think that's right) horsepower, whereas the ICE is rated for peak. An ICE's torque and power rises, peaks, and falls again - sort of like a mountain. An electric motor typically has a big wide plateau of power and torque.

When you see that one of those cars is only making say 250hp, think more like at least 600hp in your head. The dragstrip is a great dyno - if the power isn't there you won't turn the drum on a dyno, and you won't turn the times at the strip. The fact that these guys are on the fringe of ten second ETs tells the story that there is a lot of power there. It's more than just torque, or they would still be running 14 & 15s.

As I stated, my question was more about what seems to be limiting them from really awesome times, as opposed to really great times. I just wanted to know where the last bit was going. The fact that the dragster and drag bike are running in the 7s, says the power and potential is there. I basically wanted to know how they got there.

I reiterate, the dragster went from a 4spd to direct drive and went faster - that's not the problem. The drag bike and the Datsun are also direct drive.

It's also not stated just how much pedal is put into the launch of the White Zombie. With 700+lb-ft and 215 section width radial tires he may not be utilizing anywhere near its potential off the line. By the numbers, he should be way out ahead of the Mazda. Lighter car, slightly more advanced motor, better batteries now, etc.

Like I said, I think I found the answer I was looking for. I keep chiming back in because I started this thread and wouldn't want one of those guys to ever stumble across it and find the wrong message.


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## 2cycle (Jul 2, 2009)

I don't think anybody is degrading their accomplishments. I think we all have our opinion of how to go fast but we may not agree. I've proven to myself what I need to go fast for me and my vehicles, but that might not work for you. 
When I look at those numbers you posted of their performance I don't see anything out of line. What do you believe they should see? There are very accurate drag race simulators out now that when an accurate power curve and vehicle set up is loaded it can give you an accurate 1/8 and 1/4 mile performance to be expected, maybe start there. They used very uncommon drag race vehicles like that little van so aero must have played a role with that car. 
I think drag race EV's have a ways to go but the potential is there, that's why I wanted to find some equal perf. and weight components to try on our snowmobiles.


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## toddshotrods (Feb 10, 2009)

2cycle said:


> ...They used very uncommon drag race vehicles like that little van...


What little van? An EV van on the dragstrip - do tell! 



2cycle said:


> ...When I look at those numbers you posted of their performance I don't see anything out of line. What do you believe they should see?...


Using the conversion ratio as it's quoted on the White Zombie, and a drag race calculator, 780hp/772lb-ft of torque in a 1855lb car would be capable of a 7.72 @ 175mph! Discounting the power to 520hp gets 8.84 @ 153mph. 260hp puts the car where it is 11.13 @ 121mph.

Based on electric motor theory, and the performance of the two dedicated drag racers, I think the Datsun and Mazda should be in the 9s. Basically about a second faster than they are currently running. Major's theory makes sense because it would be like an ICE with a low-rpm induction setup. It would run like a beast off the line and trail off around half-track. I know a guy with a Pro Street Vega (434inch SBC; full-race TH400; Dana 60) that had similar problems. He had a street tunnel ram with two small fours,a small cam, and medium Dart heads. It was a terror on the 1/8th mile track, but ended in a Sunday drive for the last half of the quarter.

Your thinking about nitrous-like boost down the track is probably what's needed. Ultracapacitors would be great, but from what I understand the technology isn't quite there and the price is ridiculous. I would love to see a data acquistion sheet from one of their runs. They unload 1000-1500 amps at launch, I wonder what the motor is pulling from half-track to the finish line. Maybe the solution is in the controller. Zilla has been praised as the king in drag racing, but they aren't even in production right now, so development hasn't been ongoing.


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## 2cycle (Jul 2, 2009)

The little van was the "Suck Amps" postal van. That was my first EV impression, I saw it on some Discovery Channel show I think it was. As bad as a van's aero is that thing went pretty good for what it was. 
I myself have been around very large very powerful electric motors in the work place and because my father installs the drives for them on many different industrial applications. I think with the right frame of mind building these motors and drives great things can happen. I think the electrical "nitrous mode" using some sort of capacitor will be key. 
I think the electric motor industry has some learning to do about the EV applications so they can better understand the requirements and configurations we have. The more open minded people they have working on these issues the quicker we will get the parts we want. The parts being used are stuff like fork lift motors and crude controllers that were not built with racing or performance in mind. 
If we really want this EV thing to gain some knowledge really fast we need the F1 car teams to start working on it . Make an EV-F1 class and tap into their 200 million dollar a year budgets. We need real race breed components so racing can test it and then trickle down to common road use. The AC motors to me look like the only way to go for a couple reasons, lightness, broadness of power and high rpm capability. 
I also think we need at least some motor company out there to start dyno testing these motors actual peak power with max voltage it can handle and the resulting power curve as it runs up through the revs, not some industrial method of rating motors that means nothing to an EV builder. We need to know what it's capable of so we can better size it to our application.


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## Qer (May 7, 2008)

My judgement: Batteries, batteries and ... um ... I think I take batteries as my third choice. 

Take a look at this graph from Plasmaboys homepage:










Look at PWM (lower red) and current (green) and how when one goes up, the other goes down. Also look at the battery voltage (upper red) and how it's almost straight the first part of the race and then slowly declining. My first guess was that the controller limits the voltage drop, but since it's declining quite a bit at the end I think it's a pack current limit that's working here.

This means that the controller only briefly manages to get close to it's rated current (just after the serial/parallel switch) and the "secret weapon" of electric cars, constant torque, is extremely hard to keep up at these power levels. In this case the White Zombie is running at constant power rather than constant torque which of course means that the faster the car goes, the less it will accelerate.

We've seen this problem already with our 1kA-controller, the batteries can't keep up with the current demand at higher RPM's (we've already killed one battery and definitely damaged a few others) and if that's a problem at 1kA the situation of course won't improve at 2kA...

Lithium batteries aren't that much better from this aspect. When White Zombie ran on Lithium they had to dial back the battery current from 1500 Amps (the graph above is an older graph with 1000 Amp limit on an older set of lead) to 1000 Amps. Still, the White Zombie on Lithium got a better time than what it could do on lead. I guess a few hundred pounds of missing lead did the trick. 

And about capacitors, a 1 Farad capacitor @ 370 Volt stores 137 kJ. So in theory you can get 137 kW for a second (or half that for two seconds and so on), in practice you can't since you can't drain the capacitor down below the battery voltage. A rough estimation is that the controller needs at least a few houndred extra Amperes in to be able to really push full 2kA into the motor and at, say, 500 Ampere current from a 1 Farad capacitor to give the extra power the batteries can't provide it will drop 500 Volts/second (C*U=I*t is a very useful formula for estimating this), ie the charge will be gone more or less immediately in the launch.

After that the capacitor will only be dead weight and the batteries will have to take the full current themselves. Now, of course, if you got some tens of Farad it would probably improve the situation, but, uh. Nah. Where would you fit all those caps? And what would the weight do to the time? Probably not improve it...


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## toddshotrods (Feb 10, 2009)

Wow! That settles that - thanks for takingthe time to post Qer!  So, is it mainly the weight advantage helping KillaCycle and Current Eliminator achieve the performance they have?

Please come back, I would love to have more of your input in this. I gotta go right now, but I'm going to let this soak in and come back later with more thoughts and questions.

Ten points to all the people in this thread who said "batteries".


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## JRP3 (Mar 7, 2008)

Good analysis. So it looks as if they need to run higher voltages to reduce sag, and that probably means AC motors, which I think they are working on.


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## notnull (Jul 30, 2008)

They could also put more of the A123 cells in parallel to reduce the voltage sag. If they had used two of the A123 packs in parallel instead of one they would have still been lighter than the Lead setup and it would have held voltage much better. 

Steve


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## notnull (Jul 30, 2008)

From the plasma boy site:

2,652lbs car, 11.882 @ 109.58mph, with 844lbs being battery weight.

This was using 60 Hawker Genesis 12V 16XE batteries arranged in two parallel strings of 30. They pull 750A out of each string and the voltage is quoted as holding about 7V per cell. So, 7V * 30 batteries * 750A = 157.5KW or about 210 HP. This is only one string so double that for 420 HP. I don’t know that I would expect these batteries to really hold 7V under a 750A load, but even if they fall to 6V that is still 360 HP. I also saw several places in their history page where they quote horsepower numbers similar to the ones above.

1,858 lbs car, 11.466 @ 114.08mph, with 175lbs being battery weight.

That actually seems a little light to me based on other numbers they posted and is probably more like 1950 lbs. Anyway, this is an A123 pack using 110 cells in series and eight in parallel. They use 3.4 per cell as the nominal voltage and quote the pack as a 374V pack. The capacity of this pack is only about 18.4Ah. They were trying to get 1000A out of the pack which is over a 50C rate of demand. I expect the pack voltage fell below 2V per cell.

The point here is that they could simply add more packs in parallel to hold the voltage better. I have used A123 cells in other projects and 20C will give you about 2.5V per cell and 10C gives you about 3V per cell.

What would it take for them to get to 20C drawing 1500A? They would need four parallel strings of the A123 cells. So, you now have a pack that is 700lbs but would likely hold 275V under a 1500A load, that is over 550HP. Not only do you have much more power available than the lead pack but you are still 150 lbs. lighter.

You would have a 2500lb car with 550HP and 770ft-lbs of torque. So, why don’t they do this? Cost. I expect the pack of A123’s was in the 10K range. You might be able to get one built for less than that but you still need four of them. That is a lot of cash for batteries. 

Of course, this much power is likely to start breaking other parts, like motors and controllers.

Steve


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## Qer (May 7, 2008)

JRP3 said:


> Good analysis. So it looks as if they need to run higher voltages to reduce sag, and that probably means AC motors, which I think they are working on.


I'm no motor expert (*points to major*) but I don't think the AC versus DC makes much of a difference in this aspect. There's of course other aspects with different motor technologies that you have to consider, but when it comes to raw power it's simply what amount of kW you can get from the batteries and through the transmission that matters. Also, even though an AC-motor is somewhat more efficient than a DC-motor, it's the opposite for the controller (or so I've been told...). So you need more raw power and more Ah, higher C-factor or higher Voltage are just different ways to reach that goal. And also, don't forget that Lithium sag less than lead (and weight less, of course).

Changing the operating parameters is another way to trim the times. If you have a 2kA controller and only one motor at low RPM's the voltage over the motor (which is somewhat proportional to RPM) will be so low at start that you'll hit the 2kA-limit and you won't be able to push all that raw kW into the pavement. Since the motor current is then the limiting factor you in essence have four choises:



Get more current
Get a gear box
Use a Siamese motor and serial/parallel switch them
Use a Siamese motor and double controllers

Option 1 will demand a hell of a controller and motor so option 2-4 are probably more realistic. 2-3 are more or less the same thing, trading rpm for torque but in option 2 you do it mechanically and in 3 it's done electrical. Option 4 will be as good as 3 or better, but also more expensive (of course).

Actually I'm a bit mystified that noone seems to have tried that last route, because then you can (theoretically at least) push more power in the motors since parallel mode isn't limited to I/2. That of course means that the pack must be capable of more than 2kA output (or whatever current that is max for the controller) for it to make sense and that'll take a serious Lithium pack. Another bonus is, however, that you don't have to kill the power for the contactor switching which might give you another 0.1-0.2 seconds of acceleration or so. It's a high price for that last tenths, but hey, it's racing...


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## Qer (May 7, 2008)

notnull said:


> Of course, this much power is likely to start breaking other parts, like motors and controllers.


Definitely. However I doubt the Zilla will break since it's well proven that it can handle a lot of abuse and the software is actively limiting PWM to keep it running within specs. The motor is, however, definitely a weak link and repeatedly pushing 2kA through a WarP 9" is definitely not good for it. Heck, even 1kA through a WarP 9" isn't very healthy in the long run, the poor WarP that's in our dyno has shown signs that it's not too happy with how it's treated by the controller.

So I guess that's the next bottle neck...


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## major (Apr 4, 2008)

Qer said:


> I'm no motor expert (*points to major*) but I don't think the AC versus DC makes much of a difference in this aspect.


Hey Qer,

You talkin' to me 

The old series DC motor is well suited for the drag racer. Tons of starting torque. All you need is the battery and controller to put it out. This is why these guys have such impressive hole shots. And drag races are short duration, so motor (and other components) cooling can be dealt with after the run. The problem with the DC motor is the zorch limitation on I, V and RPM. So, to go faster, or quicker, with DC motors, they have to go to bigger, or more, motors.

As far as AC motors, about the only guys I know of running AC is (or was) BYU with the EV1. It didn't do too badly. Especially considering it is front wheel drive and used ultracapacitors.

The AC motor will never get the torque output per pound that the series DC does. But you can run the AC much faster and therefore gear in some of that lost torque. And the AC motor may be able to improve second half track power. But for ETs, getting going faster sooner is a big plus.

I expect to see more AC drives on the drag strip in the future. There is an electric drag event in Portland in a couple of weeks. Let's see if any Teslas show up.

Regards,

major


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## Qer (May 7, 2008)

Interesting. So an EV-dragster with AC-motor will behave more like the ICE-dragsters?

How about SepEx and BLDC, how well would they compete?


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## toddshotrods (Feb 10, 2009)

Qer said:


> ...How about SepEx...


 Yeah, how about SepEx? 



Qer said:


> ...Use a Siamese motor and double controllers... Actually I'm a bit mystified that noone seems to have tried that last route...


Maniac Mazda runs four controllers on a siamese motor (2 for each motor) but he has a lead pack.


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## Carroll_1 (Dec 18, 2007)

> I expect to see more AC drives on the drag strip in the future. There is an electric drag event in Portland in a couple of weeks. Let's see if any Teslas show up.


Been following this thread from the shadows  

The last I saw on the NEDRA list, they had six Tesla's confirmed for the race in Portland, maybe more.


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## JRP3 (Mar 7, 2008)

Tesla 12.7in the quarter mile, and that's while carrying 220 miles of battery range.
http://www.autobloggreen.com/2008/1...-to-the-drags-does-a-12-7-second-quarter-mil/


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## Qer (May 7, 2008)

JRP3 said:


> Tesla 12.7in the quarter mile, and that's while carrying 220 miles of battery range.http://www.autobloggreen.com/2008/1...-to-the-drags-does-a-12-7-second-quarter-mil/


Don't forget that the amount of batteries not only gives range but also gives top current. There's definitely no guarantee that the time will improve if you remove half the pack.


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## Tesseract (Sep 27, 2008)

CroDriver said:


> The biggest problem: There are to few Zillas!
> 
> Btw. If anyone has a HV Zilla, contanct me!!


Put your money where your mouth is:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=140332477034


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## JRP3 (Mar 7, 2008)

Qer said:


> Don't forget that the amount of batteries not only gives range but also gives top current. There's definitely no guarantee that the time will improve if you remove half the pack.


True, but less weight should also reduce current required to some degree and it depends on how close the pack is to it's maximum current to begin with. There is probably a curve where reduced weight crosses reduced current. Might need to replace the commodity cell pack with a smaller, higher C rate version made of A123's.


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## Qer (May 7, 2008)

JRP3 said:


> True, but less weight should also reduce current required to some degree and it depends on how close the pack is to it's maximum current to begin with. There is probably a curve where reduced weight crosses reduced current. Might need to replace the commodity cell pack with a smaller, higher C rate version made of A123's.


I guess that will be one of those details that the gear heads will have to tune instead of adjusting all those details in an ICE that they do today. There's always something that can be improved, adjusted, tuned etc, it's just a question what has to be adjusted.


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## toddshotrods (Feb 10, 2009)

Qer said:


> I guess that will be one of those details that the gear heads will have to tune instead of adjusting all those details in an ICE that they do today. There's always something that can be improved, adjusted, tuned etc, it's just a question what has to be adjusted.


There's usually never one "right" combination either. There are usually a few different paths to success in racing, which is one of the things that make it fun.


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## major (Apr 4, 2008)

Qer said:


> How about SepEx and BLDC, how well would they compete?


In theory, a SepEx could do what a series motor can. But can you get the required control? Deal with the high currents in the armature circuit without the series field inductance?

In my book, BLDC is an alternating current system. May or may not be sine wave. But swings positive to negative. A BLDC or PM AC motor may have higher low speed torque/starting torque than the same size induction motor. But there again, may have control issues, like at top speed. But if you have the money, take a look at it.

Regards,

major


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## 2cycle (Jul 2, 2009)

After looking at the time slip from the Tesla on the drag strip I would have to say it's pretty decent. At first I was comparing to some of our time slips with our snowmobiles and street rods and the Tesla looked pretty sluggish. Then I did find some slower street car type slips and for a car that drove off the street it does have good 60' times and 330' but from there on it lacks a little but only compared to it's short times because they were good. It partly shows good 60' because it's fairly light, not 4000# like some muscle cars. There is a real science to building transmissions and I think with the right transmission it would be an even quicker car that carries a more linear acceleration curve. I wouldn't doubt that the rpm was too high after the 1/8 mile, it could have over shot the sweet spot of the curve because it didn't have 2nd gear. The Tesla has a time slip like a pickup truck would, they are not geared for high speed. 
Still impressive as a stock street car. A tuned Honda will give it a heck of a run in the quarter mile but the Tesla will take him off the line. Still a long way to go before the batteries and transmissions are there I guess. If I were spending 100K on a car it would have at least a 3 speed tranny.


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## JRP3 (Mar 7, 2008)

2cycle said:


> If I were spending 100K on a car it would have at least a 3 speed tranny.


Even if it didn't need it? Remember they didn't build the Tesla to be a dragster, and yet it still does pretty well. It's 0-60 time beats probably 99.9% of all production cars. Dragging around extra gearing and housing you almost never use doesn't make much sense in an EV. They tried a 2 speed gear box, from two different manufacturers, and kept breaking them, so they just tweaked the motor and controller to get extra power and went with the single speed.


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## 2cycle (Jul 2, 2009)

I guess I would classify this car as kind of a super car mostly because it's quick, expensive and sporty. I never saw it as a dragster but that's how they are showing it off. As you say it has great low end accel, but they have the top speed of a $25000 sports car. I think if you geared a Z06 Vette for 130 mph top speed you might find it has a blazing 0 to 60 time as well. I can't help but think a multi speed tranny would keep it in the sweet spot better.


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## JRP3 (Mar 7, 2008)

A second speed would probably give you a higher top speed, but when you really think about it, other than marketing, what's the point of selling a Corvette, or any car, that can do 140 or more? Most will never see that kind of speed, so why should Tesla put even more expense into the vehicle that will almost never be needed? People will use hard acceleration from a stop much more often than top speed, so that's where the emphasis was put, and where EV's shine. Plus, as I mentioned, they kept breaking the two speed transmission. If they can do 125 with one speed they would certainly not need more than two if they did use a transmission.


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## DavidDymaxion (Dec 1, 2008)

*Top speed*

Besides marketing, there is gas mileage, racing, and the autobahn. While every car doesn't need those kinds of top speeds, there is definitely a niche market for it. Only a handful of cars (sports cars) advertise their top speed.

For the gas car, gearing it for high top speed will also improve the highway gas mileage. You could say the Corvette ZR1 200+ mph top speed is just a side effect from its 30 mpg highway mileage (some folks actually claim to get this).  Indeed, many cars are overgeared. My gas car is geared for 200+ mph, even though the top speed is well below this. 6th gear is just for saving gas, top speed is achieved in 5th.

The whole point of Tesla starting with a sports car is bragging rights -- you'll note they didn't start with a minivan! Many of my racing buddies never heard of the GM EV1, Honda EV+, Chrysler TEVan, Ranger Electric, etc. but they all have heard about the Tesla. It is amazing to me how many have come up to me asking if I'd heard about the Tesla as soon as they hear I have an electric car.

I have played on the road racing track and Salt Flats, and have seen 120+ mph a bunch of times -- that is living life to its fullest! If I were rich I'd love to do that in a Tesla!

I wonder how well a Tesla would do crawling up a steep hill in hot weather at very low speed? I'm sure it's engineered to do that, but it would be less stress on the motor, controller, and batteries if it had lower gearing.



JRP3 said:


> A second speed would probably give you a higher top speed, but when you really think about it, other than marketing, what's the point of selling a Corvette, or any car, that can do 140 or more? Most will never see that kind of speed, so why should Tesla put even more expense into the vehicle that will almost never be needed? People will use hard acceleration from a stop much more often than top speed, so that's where the emphasis was put, and where EV's shine. Plus, as I mentioned, they kept breaking the two speed transmission. If they can do 125 with one speed they would certainly not need more than two if they did use a transmission.


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## Qer (May 7, 2008)

*Re: Top speed*



DavidDymaxion said:


> I'm sure it's engineered to do that, but it would be less stress on the motor,


Possibly.



DavidDymaxion said:


> controller,


Probably not.



DavidDymaxion said:


> and batteries


Nope.



DavidDymaxion said:


> if it had lower gearing.


Which also would increase the losses in the drive train.


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## Batterypoweredtoad (Feb 5, 2008)

*Re: Top speed*



Qer said:


> Possibly.
> 
> 
> 
> ...


So it's not more stressful to the batteries and controller to spend more time at higher amps? Is the difference in efficiency of an electric motor/controller so little across the operating range that the added inefficiency of adding another gear to the transmission makes a net loss? Everything i've read here and elsewhere leads me to disagree with you. I think they gave up the gear purely because they got tired of trying to get a transmission that didn't break. I think they lost range, speed, and efficiency in the process. 
Qer, You seem to know alot about this stuff, so if I am talking out of my knowledge base, I wouldn't mind being proven wrong.


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## DavidDymaxion (Dec 1, 2008)

*Re: Top speed*

Remember, 0 rpm is 0% efficient -- slowly crawling up a steep hill is barely above this operating point. It's analogous to slipping the clutch to go up a steep hill very slowly. In a car geared for 120+ mph that's got to take a lot of current.

That's generally not really a problem in day to day driving, as you'd only spend a short moment in the very low efficiency range.

Will a lower gear lower efficiency? It depends. If you are lowering the ratio of an existing gear pair, not much change. If you are adding a gear or 2, than that drops the efficiency. I've heard each gear mesh has a loss of about 3%.


Qer said:


> Possibly.
> 
> Probably not.
> 
> ...


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## Qer (May 7, 2008)

*Re: Top speed*



Batterypoweredtoad said:


> So it's not more stressful to the batteries and controller to spend more time at higher amps?


A controller has no moving parts, there's nothing that gets worn down by time or load. To stress a controller you have to expose it to high temperatures (100C or above on the die) while pulling serious motor current and I have a hard time thinking that a controller that can handle 0-60 mph in less than 4 seconds and has a (electronically limited) top speed of 125 mph will be stressed by going slowly uphill. Sure, going uphill takes more current than creeping along a flat surface but long before the controller will even get close to serious currents the car should be accelerating, probably pretty hard.

Also, think of a controller as a power converter (not a voltage- or current converter) and at every given moment battery current is less than or equal to motor current and motor voltage less than or equal to battery voltage. Like this:

Pmotor = Pbattery (and some added losses, but I'll ignore them for now) or:

Im*Um=Ib*Ub

When you're going slow, the voltage over the motor is much lower than battery voltage so that gives that battery current must be much lower than motor current. At low speeds you simply can't stress the batteries because even if the motor is working at full current the battery current will be proportionally as low as motor voltage is to battery voltage. Changing gear to a higher rpm will, undoubtedly, decrease the current but it will also increase the voltage and the amount of power you use won't change very much (theoretically not at all, but in real life the losses will probably drop a bit).

The batteries will have their toughest time when you're giving full throttle at high speed (and that's when you want a battery current limit function...).



Batterypoweredtoad said:


> Is the difference in efficiency of an electric motor/controller so little across the operating range that the added inefficiency of adding another gear to the transmission makes a net loss?


I didn't say that. I just pointed out that there's no such thing as a free lunch. A gear box will add losses which probably will decrease top speed (at least in a transmission geared for maximum top speed) and might(!) affect range (positive or negative will depend on your driving habits and gearing). A gear box might, however, have other advantages that makes it preferable anyway, like better acceleration or a more versatile vehicle.



DavidDymaxion said:


> Remember, 0 rpm is 0% efficient -- slowly crawling up a steep hill is barely above this operating point. It's analogous to slipping the clutch to go up a steep hill very slowly. In a car geared for 120+ mph that's got to take a lot of current.


I kinda fail to see the point to run a motor at 0 RPM when there's brakes that are more energy efficient at holding the car at a stand still. True, the efficiency is 0 at 0 RPM, but it's also 0 at 0 torque, both cases are pretty pointless from a car perspective and the efficiency increases very fast as soon as the car is moving.

And high current? You don't think 120+ mph will crave some serious current...? Now we're talking system stress!


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## Batterypoweredtoad (Feb 5, 2008)

Qer-if you put a 2.0 reduction first gear in the Tesla you cut load by 1/2 at the same speeds. Your battery, controller, and motor, would have roughly 1/2 the load to achieve the same exact acceleration.


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## Tesseract (Sep 27, 2008)

Batterypoweredtoad said:


> Qer-if you put a 2.0 reduction first gear in the Tesla you cut load by 1/2 at the same speeds. Your battery, controller, and motor, would have roughly 1/2 the load to achieve the same exact acceleration.


Ummm... this is basic physics, 'toad:

f = m*a (f = tractive force; m = mass; a = acceleration)

It takes a certain amount of power to accelerate a vehicle to 60mph in 5 seconds. Power, which is torque x rpm. A 2:1 gear reduction doubles the required rpm from the motor but halves the required torque.


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## 2cycle (Jul 2, 2009)

After looking at the Tesla power and torque curves, I'm not sure why they call this a 13000 rpm motor, just because it can mechanically turn that fast doesn't mean it should be used that high. I think someone earlier in the thread made the point of saying it was geared for the slower corner to corner driving not top end. If I could see a data recording of the quarter mile run I'm betting they are in a major over rev situation where the power drops quickly but still has enough power to accelerate a light weight car up to 125 mph. The existing gear in it looks like it works great as a first gear on the strip but I would keep it below 8500 rpm at the lights. Then there shouldn't be a reason mechanically that it would lose acceleration in the quarter.
I still say one trip to the transmission guru's and you would have a 150 mph Tesla for the same money. 
And the issue with breaking the tranny, with a wimpy 200 or even 300 lb/ft of torque tells me they tried to build the tranny themselves and/or wanted the tranny to weigh 20 lbs to "keep it light". Drag cars have 60' times in half the time the Tesla ran and the drag cars weigh 500 to 700 lbs more so I guess the big torque of the Tesla wasn't the problem.
The racer I'm building will be using a CVT pulley system capable of transmitting 200 lb/ft of torque with a final drive geared for 165mph for quarter mile, which is what the vehicle runs for speed now.


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## DavidDymaxion (Dec 1, 2008)

John Wayland recently reported the Tesla is relatively sluggish up to about 30 mph, and then really takes off 30 to 60 mph. (A sluggish that still beats most cars!)

So why isn't it just as fast off the line as at 30 mph?

BTW, I observed the same behavior in the EV1s I rented. They would take off with less vigor than they had at about 30 mph.


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## 2cycle (Jul 2, 2009)

My guess would be it's in the controller. I can only assume one would need to "ramp in" that kind of torque when running DOT tires. With ICE we do it in the electronics with rev limiters and altered ignition timing.


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## toddshotrods (Feb 10, 2009)

2cycle said:


> ...one would need to "ramp in" that kind of torque when running DOT tires...


DOT *street-biased* tires. There are DOT tires that are basically racing tires with a groove here and there, and a little extra sidewall stiffness. Just a clarification, but your point is valid. Most street tires can't take the ramp up of torque from an ICE, let alone a quick hit of full torque from an electric motor. Contact area and composition obvisouly matter, but real street tires have their limits.



2cycle said:


> ...With ICE we do it in the electronics with rev limiters and altered ignition timing.


And in the hard parts with soft-hit torque converters, skillful clutch work, etc. I raced street-legal dragbikes, with no wheelie bar, and it was all about who could "Slide" the clutch most effectively.


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## blwncrewchief (May 29, 2008)

Tesseract said:


> Ummm... this is basic physics, 'toad:
> 
> f = m*a (f = tractive force; m = mass; a = acceleration)
> 
> It takes a certain amount of power to accelerate a vehicle to 60mph in 5 seconds. Power, which is torque x rpm. A 2:1 gear reduction doubles the required rpm from the motor but halves the required torque.


Tesseract I agree with you but, I think we need to look at it in a little more detail so hopefully everyone can understand it a little better. If we are using that equation and we know our mass in pounds than we need to calculate our "tractive force" in pounds to get our acceleration. If we are starting with foot pounds of torque at the motor than we must calculate out our "tractive force" in pounds of force. Let's keep it simple and we'll leave the stuff like rolling resistance, aero drag, traction limitations, accelerating the drive line mass, and efficiency losses out.

In order to calculate our "tractive force" in pounds we have to take our motor torque multiplied by all gearing and divide by our tire radius. So for a normal vehicle it would look like this: Tractive force in pounds = motor torque x transmission ratio x axle ratio / tire radius.


So let's set up a few simplified examples. We'll assume at first the vehicle is at a dead stop and makes 100 foot pounds of torque.

Example 1) no transmission, a 4-1 axle ratio, and a 24" diameter tire.
100ft# x 1 x 4 / 1 = 400 pounds of "tractive force"

Example 2) 2-1 transmission ratio, 4-1 axle ratio, and a 24" diameter tire
100ft# x 2 x 4 / 1 = 800 pounds of "tractive force"

Example 3) 4-1 transmission ratio, 4-1 axle ratio, and a 24" diameter tire
100ft# x 4 x 4 / 1 = 1,600 pounds of "tractive force"

So now we can see why gearing is used. The vehicle with no transmission would have to generate 400 foot pounds of torque from the motor to equal the "tractive force" available of the vehicle with the transmission with a 4-1 transmission gear ratio and 100 foot pounds at the motor. Leaving speed and rpm out it is mostly this simple and straight forward.

Now let's go just one step further and answer why torque versus rpm matters. Simply, it's all about the gearing to get our "tractive force". Our "tractive force" is the variable to get our acceleration rate since generally our "mass" is fixed. Let's use one more set of simple examples to show why. We'll assume a fixed point of needing 500 rpm at the tire for the speed we are calculating at. Next we'll assume we have three motors that can all produce 100 ft# of maximum torque. Motor 1 can produce maximum torque at 2000 rpm, motor 2 at 4000 rpm, and motor 3 at 8000 rpm. Now we use our formula to figure our transmission gear to use the maximum torque of the motor assuming the same variables as the above examples. If we need 500 rpm at the wheel and we have a 4-1 axle gear ratio than we need 2000 rpm from the transmission to the axle gear. So we need to figure our transmission gear needed for: motor rpm / transmission ratio = 2000 rpm.

Motor 1) 2000 motor rpm / ? trans gear ratio = 2000 rpm trans out speed 
2000 motor rpm / 1 = 2000 rpm trans out speed

Motor 2) 4000 motor rpm / ? trans gear ratio = 2000 rpm trans out speed 
4000 motor rpm / 2 = 2000 rpm trans out speed

Motor 3) 8000 motor rpm / ?trans gear ratio = 2000 rpm trans out speed
8000 motor rpm / 4 = 2000 rpm trans out speed

Now from our formula for calculating our "tractive force" we know what is going to happen when we calculate it out for these motors at a given speed. So our "tractive force" in pounds at 500 tire rpm in the above vehicle examples would be: motor 1) 400 pounds of "tractive force", motor 2) 800 pounds of "tractive force", and motor 3) 1600 pounds of "tractive force". That is the simple reason a motor that makes the same amount of torque at a higher rpm will accelerate a vehicle quicker at any given speed, if it is geared correctly, than the motor with the same torque at a lower rpm.


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## Tesseract (Sep 27, 2008)

blwncrewchief said:


> ...If we are starting with foot pounds of torque at the motor than we must calculate out our "tractive force" in pounds of force.
> ...
> So now we can see why gearing is used. The vehicle with no transmission would have to generate 400 foot pounds of torque from the motor to equal the "tractive force" available of the vehicle with the transmission with a 4-1 transmission gear ratio and 100 foot pounds at the motor. Leaving speed and rpm out it is mostly this simple and straight forward.
> ...


Nice work, blwncrewchief, and I don't disagree with your analysis, BUT, please note that I was responding to this:



> Qer-if you put a 2.0 reduction first gear in the Tesla you cut load by 1/2 at the same speeds. Your battery, controller, and motor, would have roughly 1/2 the load to achieve the same exact acceleration.


Merely inserting a 2:1 gear reduction does not cut the _POWER_ required to accelerate to a given speed in a given time in half, it merely cuts the torque required in half (while doubling the motor RPM, and since power = torque x rpm, well....)

_That_ is the point Qer was making, and which I reiterated.

Qer also noted that while there may be _practical_ benefits to using a gear reduction and/or transmission, getting a "free lunch" was not one of them.

In the end, all controllers/motors are power limited, and that implies a definite and predictable maximum rate of acceleration.

EDIT: Or to put it another way, let's say it takes 10hp for a vehicle using direct-drive to maintain 40mph on a 5% incline; guess how much power will be needed to maintain the same 40mph on the same grade if instead of direct drive a 2:1 gear reduction is employed?

EDIT^2: blwncrewchief, you are totally comparing apples to oranges, btw. You need to keep tractive force (torque at the wheels, in other words) the same and the rate of change in RPM (ie - acceleration) the same and then figure out what will be demanded of motor torque and rpm to achieve that specific figure for various gear reductions (including 1:1). It comes out the same every single time.


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## Batterypoweredtoad (Feb 5, 2008)

OK so in a perfect world where the motor is equally efficient at all rpms and volt/amp levels power is power is power. But doesn't running at higher amps typically mean less efficiency? Wouldn't you spend much more time at high amps using a single gear trans instead of a 2 speed? Wouldn't you therefore be less efficient the same rate of acceleration?


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## 2cycle (Jul 2, 2009)

toddshotrods said:


> DOT *street-biased* tires. There are DOT tires that are basically racing tires with a groove here and there, and a little extra sidewall stiffness.
> .


 I don't believe the Tesla ran the special DOT drag tires. I have seen pics of one of the current EV drag cars using wrinkle walls which is a huge advantage in cars rather than the stiff sidewalls like bikes.
I watched Ricky Gadson school everybody on how to use a clutch to win a drag race about 15 years ago in a Supersport class, rather impressive. 
Like you, I've been into racing for 20 years, 10 years at the professional level, and can't help but think I can make some of these EV drag cars quicker and faster with the proper transmission. I can only assume that traction control should be easier on an EV compared to ICE, and we have pretty good traction control on those now. 
I haven't heard any experienced EV racers chime in about traction control yet, please tell me they do use it, right?


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## Overlander23 (Jun 15, 2009)

Depends on the motor design and "capacity". There are obviously limits. Once you start getting closer to a motor's limit by pumping more amps through it you start generating heat rather than motion... that's the inefficiency.

In this case, a higher voltage (less torque, more speed) motor with a gearbox will be more efficient from a motor standpoint, not necessarily a system standpoint. You're fundamentally adding another point of frictional inefficiency into the system with a gearbox.

There's no motor that can do it all in every situation. If you start off with a gearbox on a motor that will be used 99% of the time in its efficient range, you're just being inefficient.

Regarding the drag racers... no one has mentioned aerodynamics. Anything much over 40mph starts involving really pushing air. Once you get to the 150mph level, while the race is short, you're expending a tremendous amount of energy on fighting the atmosphere.

At the higher drag levels (sub 7 secs) you're typically seeing speeds in excess of 200mph... That's a lot of HP! i just saw Terminal Velocity, a jet turbine drag car, do an exhibition 1/4 mile in 6.5 secs at 250mph, and turbines typically don't put out a lot of "torque".

Torque gets you off the line quickly, HP gets you top speed. That and aerodynamics...

Also someone correct me if I'm wrong, but a motor might not be that inefficient at slow speeds (the climbing a hill slowly example), but the controllers are more inefficient at part throttle. So they'll heat up. But I agree that they probably won't fail if properly designed in the first place. Zero rpm is 100% efficient if no power is being used... and the goal is to go nowhere!



Batterypoweredtoad said:


> OK so in a perfect world where the motor is equally efficient at all rpms and volt/amp levels power is power is power. But doesn't running at higher amps typically mean less efficiency? Wouldn't you spend much more time at high amps using a single gear trans instead of a 2 speed? Wouldn't you therefore be less efficient the same rate of acceleration?


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## Qer (May 7, 2008)

Overlander23 said:


> There's no motor that can do it all in every situation. If you start off with a gearbox on a motor that will be used 99% of the time in its efficient range, you're just being inefficient.


I'm wondering how much the efficiency actually will change. Will the efficiency actually change that drastically if you shift gear and the motor speed goes from, say, 250 rpm to 500 rpm that it actually matters?

From a drag racing perspective I think the REAL benefit is that there's always a current limit in the controller that will reduce total power from the motor at low rpm's and that when you change gear the motors back-EMF increases and thus you get more power. That's where the serial/parallel-shift of a Siamese DC-motor makes sense, you more or less get an electric gear box.

Of course, there's a few not so good side effects with this approach so it's maybe not the best way to choose for a commuting car, but who cares on a drag racing strip...? 



Overlander23 said:


> Also someone correct me if I'm wrong, but a motor might not be that inefficient at slow speeds (the climbing a hill slowly example), but the controllers are more inefficient at part throttle. So they'll heat up.


Hm. This is more Tesseracts expertise but even though I think you're correct that the inefficiency will drop a bit at lower speeds (ie low back-EMF, unless I got my numbers horribly wrong), there's a serious black art in calculating the losses and max power depending on current, voltage, switch frequency, duty cycle etc so it might be much more complicated than that.

However, the number one parameter for energy loss in the controller is motor current. It's not increasing linear even but there's an exponential part in it as well since Vce (or Vds on a MOSFET) increases with increasing current. So the worst heat problems will be seen at max throttle. Best efficiency controller wise is, however, much more complicated to calculate and my models aren't quite up to speed yet so I'll leave that to Tesseract...


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## Overlander23 (Jun 15, 2009)

From a pure motor standpoint it may not change at all. Depends if 250rpm to 500rpm gets you out of the motor's designed efficiency range. The siamesed DC motor is a neat idea, and while it has similar effects to a gearbox, you're essentially rewinding the motor and therefore changing its characteristics. Unlike adding a gearbox, you won't add more inefficiency unless you operate the motor outside of its range. It's a neat idea.

It all depends on motor design. A brushless motor achieves close to 98% efficiency within its rated range. So, it wouldn't matter much if you geared it or not (within its range). All that energy still gets converted to motion at a high level of efficiency, except that if you add a gearbox the system efficiency goes down.

A brushed motor might be more efficient at lower rpm, because of the physical effects of motor arcing due to the brushes bouncing on the commutator being increasingly problematic at higher rpm. Compared to a brushless design, a brushed motor will, off-the-bat, be more mechanically inefficient, but they also typically have, I would guess, a smaller efficient operating envelope within which adding a gearbox might or might not be beneficial just to keep it operating within its envelope.




Qer said:


> I'm wondering how much the efficiency actually will change. Will the efficiency actually change that drastically if you shift gear and the motor speed goes from, say, 250 rpm to 500 rpm that it actually matters?


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## Batterypoweredtoad (Feb 5, 2008)

I guess what I have been trying to get to is the idea of staying at lower amps by using another gear. Most of these cars have a gear reduction system of some sort so they are already suffering some of the loss of efficiency of a transmission. If what someone said above is true that each gear mesh is worth 3% energy loss, then you should be able to add another gear for about 6% loss. Does a well developed AC motor and controller combo vary it's efficiency by more than 6% through a large part of its range?

I understand I was flawed in my thoughts on total power used. It does take the same power at the wheels to get down a dragstrip at the same rate of acceleration no matter how you change the gearing. But for acceleration you should be able to use your entire rpm range twice down the same track instead of once getting drastically better acceleration. (I guess you would be using about twice the power though )


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## toddshotrods (Feb 10, 2009)

Batterypoweredtoad said:


> ...But for acceleration you should be able to use your entire rpm range twice down the same track instead of once getting drastically better acceleration. (I guess you would be using about twice the power though )


That's pretty much the setup I'm planning, though I won't have a large enough split between ratios to allow me to use the entire rpm range again. The question though is how much power (how big of a battery pack) do you need to effectively run twice in the same time/distance? At what point does the weight of the batteries begin to overcome the available power?

Could that be what led to the current EV drag racers converting to direct drive? Maybe they didn't have enough "juice" left to use the gears. Having your motor in its most efficient range is useless if your batteries are exhausted. Current Eliminator went from using a 4spd transmision in (I think) four versions to direct drive in the latest. Drag racers might not always understand all the science behind what they're doing, but they are very scientific about getting to the finish line first. Regardless of what theories say lab tests give you concrete evidence. In this case the laboratory is on the strip. Test results say that for some reason one reduction ratio works best.


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## JRP3 (Mar 7, 2008)

toddshotrods said:


> Could that be what led to the current EV drag racers converting to direct drive? Maybe they didn't have enough "juice" left to use the gears. Having your motor in its most efficient range is useless if your batteries are exhausted.


 Just to keep current levels up they have to carry much more battery than "just enough" to finish a run, so I doubt that's a problem.


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## Batterypoweredtoad (Feb 5, 2008)

JRP3 said:


> Just to keep current levels up they have to carry much more battery than "just enough" to finish a run, so I doubt that's a problem.


I guess the question would be if they currently stay at current limit for the entire run. If not, and adding a gearbox meant more time at current limit-could they maintain that extra time with the current battery setup?


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## toddshotrods (Feb 10, 2009)

Batterypoweredtoad said:


> I guess the question would be if they currently stay at current limit for the entire run. If not, and adding a gearbox meant more time at current limit-could they maintain that extra time with the current battery setup?





Qer said:


> My judgement: Batteries, batteries and ... um ... I think I take batteries as my third choice.
> 
> Take a look at this graph from Plasmaboys homepage:
> 
> ...


If the battery pack is the problem how can adding another ratio help? When you shift, won't you be asking the pack for more current not less. Not as much as getting the vehicle moving from a standstill, but still enough to push it back towards its rpm red line again. My initial question was more about why cars like the White Zombie and Maniac Mazda aren't running as close to their ICE counterparts as KillaCycle and Current Eliminator are. The biggest difference between them is weight. The bike is nearly a third of the weight of the Datsun with the lithium pack. The dragster is 40% lighter. Unless I am mistaken current gives you torque. The more weight you have, the more torque it takes to get it down the track.


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## toddshotrods (Feb 10, 2009)

The more I read, the more I research, and the more I think about it, I am considering running direct-drive, and not even worry about the extra ratio from the Gear Vendors OD. From what I'm seeing it sounds like the money would be better spent on more lithium batteries, and less weight.


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## Qer (May 7, 2008)

toddshotrods said:


> If the battery pack is the problem how can adding another ratio help? When you shift, won't you be asking the pack for more current not less.


Um. Pm=Pb, again. Stop thinking of the controller as a current or voltage converter, it converts POWER! You can see the controller as an electrical gear box, but instead of trading rpm for torque you trade voltage for ampere.

What you can do with the gears is moving motor- and controller into a better operating range, as with an ICE, but the amount of power you pick out of the battery pack will be the amount of power you get down in the pavement + electrical and mechanical losses. Since pack voltage is (more or less) constant, the battery current only goes up if you get more power out.



toddshotrods said:


> The more I read, the more I research, and the more I think about it, I am considering running direct-drive, and not even worry about the extra ratio from the Gear Vendors OD.


Just remember that White Zombie, and also Killacycle, has a "gear box", it's just electrical.


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## toddshotrods (Feb 10, 2009)

Qer said:


> Um. Pm=Pb, again. Stop thinking of the controller as a current or voltage converter, it converts POWER! You can see the controller as an electrical gear box, but instead of trading rpm for torque you trade voltage for ampere.
> 
> What you can do with the gears is moving motor- and controller into a better operating range, as with an ICE, but the amount of power you pick out of the battery pack will be the amount of power you get down in the pavement + electrical and mechanical losses. Since pack voltage is (more or less) constant, the battery current only goes up if you get more power out...


I think I understand that, I just suck at communicating what I am thinking. The problem is compounded by the fact that I am new to this, and just learning the terminology.



Qer said:


> ...Just remember that White Zombie, and also Killacycle, has a "gear box", it's just electrical.


Theoretically, can a similar effect be accomplished with SepEx?


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## Qer (May 7, 2008)

toddshotrods said:


> Theoretically, can a similar effect be accomplished with SepEx?


Theoretically I can't see why a sepex siamese couldn't be serial/parallel-shifted but I don't know about a controller that can do it automatically (like the Zilla can shift a Siamese series) and haven't heard of anyone trying. It'll put some new, interesting demands on the controller since the field current would have to be adjusted to match the changed situation.


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## JRP3 (Mar 7, 2008)

I believe both GreenT and 2SSIC went direct drive, single motor:
http://www.ssinc.us/index.asp


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## toddshotrods (Feb 10, 2009)

I told you I suck at communication! I'm actually in college for communication to try and rectify that now - not working so far!  I didn't mean a siamese sepex - interesting idea though.

I meant can a SepEx's ability to control motor speed achieve an electrical gear box effect, like the siamese motors do when they switch from series to parallel? I don't mean can they do they same thing, or accomplish the same thing, but rather could it provide any similar type of "electric gear change" effect?


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## JRP3 (Mar 7, 2008)

I think the variable field allows a larger power band which would reduce the need for "shifting".


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## toddshotrods (Feb 10, 2009)

I read White Zombie's entire history page yesterday, and plan to spend some time in the photos and videos there today. I tried to check out the other site (Cobra and Green T) but their site layout and navigation is beyond my patience level.

The conclusion I am coming to is - direct-drive! The serious racers all got faster after they went direct drive. The more I read White Zombie's history the more I started to realize the answer to my initial question. I think it's equal parts battery and chassis. The KillaCycle team loaned them one A123 pack for one race. They really didn't have enough time to work with the pack and find out what they could do with it. With his normal lead packs there has been a lot of experimentation to basically come full circle back to what he started with. Early on, when the car was making some of it's best improvements, his original pack was also on its way out. Then he started experimenting with other battery configurations that didn't deliver as well.

Compounding the problems, he has also been doing a lot of stuff with the chassis and motor setups, at the same time. I'm actually more impressed that he has achieved the levels of performance he has on his budget. One of the golden rules of racing is you don't mess with too many things at the same time. It makes it too hard to gauge the benefits/loses. I think he's just getting back on track from when he originally switched to the siamese motor, from the Kostov. It's almost like he started building a whole new car at that point, and he's actually made significant progress.

Imagine putting his current motor and drivetrain setup (siamese motor, Zilla, aluminum shaft, race-prepped 9-inch) into a similarly built and prepped chassis! He is already launching hard enough to leave bona fide muscle cars like they're family sedans. A dedicated chassis would put more of that energy on the ground, in the form of forward motion. Take it a step futher and add a serious lithium battery pack, and I think the performance would be almost mind-boggling.

With a final weight somewhere between the Datsun and the Current Eliminator dragster, direct-drive, taller rear tires (than White Zombie's 24-inchers), a hard-working chassis, and the right motor/battery setup, I think I'll be happy. 

The one thing I have left to figure out is if I can get enough RPM out of my motor to reach my goals. I emailed the expert on that today. After I get a number from him, and crunch some on my end, I will make my final decision on the transmission issue.


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## Qer (May 7, 2008)

Mmm. NOW you're talking!


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## caspar21 (Apr 8, 2009)

does anyone have any hard numbers of efficiency losses
due to using ICE transmissions vs 1 speed rear end?
maybe real world info from a conversion that has used both?


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## Matthijs (Jun 19, 2009)

This is an interesting video on the 2SSIC battery specs:






960 cells series/parallel configuration. 80 in series and 12 in parallel. 2400 amps at 300 volt.


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## Bowser330 (Jun 15, 2008)

We need more information on 

"Smoke Screen" Chevy S10 EV

11.083 secs @ 119.91 mph (http://www.nedra.com/record_holders.html)

Single motor configuration = 13" custom modified DC motor @ *393 Volts!*!

direct drive 3.25 ratio (28" tall tires)

Single Zilla 2K (2000A) 

Weight 3300lbs

Tire width 7.5"

Lithium batteries

Updated...


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## Qer (May 7, 2008)

Just search on KilowattA798 on EVDL and there's a lot of info.


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## Bowser330 (Jun 15, 2008)

Thanks Qer...I found some extra information...

Definitely the 60ft times look good for these electric drag cars/trucks, so I have to retract my previous assumption that AWD would improve 1/4 mile times...

What looks like the key is higher voltage....the higher voltage will allow for more amps to be drawn at higher rpms....

With a pack sagging to 140V, the Evnetics controller can pull 1000A up to 2000rpm..

I wonder if the pack voltage was 300V then it should be able to pull max amps (~800) up to 3000rpm...

800A in 13" kostov motor = 300ftlbs


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## 2cycle (Jul 2, 2009)

caspar21 said:


> does anyone have any hard numbers of efficiency losses
> due to using ICE transmissions vs 1 speed rear end?
> maybe real world info from a conversion that has used both?


I doubt anybody has had a 2 or 3 speed tranny built with the ratios needed for an EV. I bet most people that have used trannys just run what they got from an ICE set up and then realized it wasn't working any better than direct so they remove the tranny.

Better yet does anybody have any hard numbers on motor performance compared to some data from a quarter mile run, that would answer way more questions , in my mind anyway. 

I'm not buying a motor for my drag racer until I look around more and find the motor with the right rpm and power range that suits our chassis. It has to be light whatever it is, the chassis can't handle lots of weight.


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## caspar21 (Apr 8, 2009)

i am guessing you are interested in the performance on the 1/4 mile. while i am interested on performance on the street.

similar but accel is not the same as efficiency
you would easily use 4x the power if you thought it would knock 1/2 a second off yur et. i would not make that tradeoff as 4x would take my 100mile range down to 25 mile range.

back to the original question..(modified of course)
has anyone got real life experience in comparing the use of
an ice transmission on an ev with direct drive?
now we are looking for approx efficiency differences as well as 
1/4 mile et's.

example of this would be where someone made an EV using an original ice transmission and got data on range etc, then removed the transmission to go direct drive. then took more data on range etc.

was the acceleration tradeoff at the bottom end worth the losses involved in removing the drag of the transmission?


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## toddshotrods (Feb 10, 2009)

No disrespect intended, but could you please start a new thread to discuss that. This thread is supposed to be dedicated to drag race performance. It's really not even about direct-drive vs transmission. We were really discussing whether or not a transmission was necessary for increased performance. The thread has already taken too far of a turn towards debating that issue.


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## toddshotrods (Feb 10, 2009)

Bowser330 said:


> We need more information on
> 
> "Smoke Screen" Chevy S10 EV
> 
> ...


Thanks for posting that Bowser. That's really close to the combination I'm working on. There's nothing like a big freakin torque motor! He's pulling a 3300lb vehicle through the quarter-mile in 11.083 seconds, and up to about 120mph, with 3.25 gears! He's only turning around 4682rpm through the traps! I'm going to have a good time!


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## 2cycle (Jul 2, 2009)

Matthijs said:


> This is an interesting video on the 2SSIC battery specs:
> 
> 
> 
> ...


I just watched this video and with the power that they are getting from these batt packs now I think you will see some even more impressive numbers. With the monster torque he says his motor makes he is on par with a small block full race prepped engine (900 hp), in a 2500 lb car that will really haul the mail. 
It looks like they are approaching a high enough power at nearly high enough rpm so you will not see much holding them back. Of coarse I wouldn't stop trying to make it quicker until I was in the 1.20's for 60 ft times with a light car like Zombie, that's what a Ford Mustang with drag tires and nitrous or turbo launches like. 
With 900 hp like this guys EV car, a 2 speed gear box with about 25% to 35% reduction for first gear should achieve about the same numbers as the 10 second Mustangs.


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## Bowser330 (Jun 15, 2008)

toddshotrods said:


> Thanks for posting that Bowser. That's really close to the combination I'm working on. There's nothing like a big freakin torque motor! He's pulling a 3300lb vehicle through the quarter-mile in 11.083 seconds, and up to about 120mph, with 3.25 gears! He's only turning around 4682rpm through the traps! I'm going to have a good time!


Anytime...

I like the idea of large motor and large controller...problem is....there are no controllers in development right now that will be able to dish out 400V and 2000A...The Zilla2K is what seems to be the only thing capable, however sourcing one might be an issue...


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## Tesseract (Sep 27, 2008)

Bowser330 said:


> ...I like the idea of large motor and large controller...problem is....there are no controllers in development right now that will be able to dish out 400V and 2000A...The Zilla2K is what seems to be the only thing capable, however sourcing one might be an issue...


True, and while we are planning on doing a 2kA version of the BMF at some point, it won't be anytime soon. After all, what's the market for that kind of controller? 4-5 units? 10 if we are lucky?

Of course, a good chunk of the development effort we expended on the 1kA controller can be applied to the 2kA controller, but it won't be as simple as paralleling four IGBT modules instead of two.

Also, there's the small matter of needing motors capable of handling this amount of power. I mean, even Siamese WarPs ain't gonna cut it.


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## CroDriver (Jan 8, 2009)

Tesseract said:


> True, and while we are planning on doing a 2kA version of the BMF at some point, it won't be anytime soon. After all, what's the market for that kind of controller? 4-5 units? 10 if we are lucky?
> 
> Of course, a good chunk of the development effort we expended on the 1kA controller can be applied the 2kA controller, but it won't be as simple as paralleling four IGBT modules instead of two.
> 
> Also, there's the small matter of needing motors capable of handling this amount of power. I mean, even Siamese WarPs ain't gonna cut it.


Ask CafeElectric how long their waiting list is 

I would purchase at least 2 400V 2000 Amp controllers if there where some on the market



Tesseract said:


> Put your money where your mouth is:
> 
> http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=140332477034


This one is already sold 

My opinion is still that the Controllers are the biggest problem for really powerful EVs. You CAN buy and build a battery pack for 500+ kW (A123), you can buy a double-kostov that can run on 350V @ 1000 Amps X2 but you CAN'T buy such a controller


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## Tesseract (Sep 27, 2008)

CroDriver said:


> Ask CafeElectric how long their waiting list is
> 
> I would purchase at least 2 400V 200 Amp controllers if there where some on the market
> 
> This [Zilla Z2K] is already sold


I *think* virtually all of those were Z1KHV models; dunno how the waiting list broke down between the 1kA and 2kA versions.

That said, keep in mind the 1kA and 2kA ratings are strictly a short-time peak and that the continuous current ratings are a more modest ~350A and ~700A respectively.

And yeah, I was kind surprised that Z2K went so quick, and at the Buy It Now price of $6500, even. Hmmm... even if we did only sell 4 or 5 2kA controllers we could just about cover the incremental development cost.


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## toddshotrods (Feb 10, 2009)

Bowser330 said:


> Anytime...
> 
> I like the idea of large motor and large controller...problem is....there are no controllers in development right now that will be able to dish out 400V and 2000A...The Zilla2K is what seems to be the only thing capable, however sourcing one might be an issue...


I think that's coming. When these guys start putting the right numbers on the clock, the demand will increase to the point where building them looks like a good business venture. 11.08 @ 119.9mph is knocking at the door. For a street-legal drag racer, a lot of respect comes with crossing the ten second barrier.

Don't overlook Tesseract and Qer's new controller either. They're already aiming for 200+ volts/1000amps, seem conservative in their claims, and are still conducting limited testing due to their hard parts (motor and dyno).

*EDIT*
Wow! I didn't realize how many posts had been made between when I started typing mine, and submitted it! I don't think $6500 is a lot for what it does and would gladly pay it for a controller that allows me to reach my vehicle's maximum potential. Performance comes at a price, no matter what you're using to get to it. The _cheap-as-possible-so-I-can-recoup-the-initial-cost_ mentality has to be put on the shelf, if you're looking to race.


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## 2cycle (Jul 2, 2009)

Can somebody supply me with some actual numbers on what's "wanted" from a controller, I'm talking to make big hp for street or strip. While I'm just getting into this EV stuff I didn't realize it was so hard to find the controller to make it all work. If I can get some real info on whats needed I will run it by my father, he specializes in drive systems for AC and DC motors, although he doesn't ususally deal with small motors (mostly in the 1000's of hp) he may be able to steer us in the right direction or even build it. I brought it up to him this weekend while we were hanging some drywall at my house and just chattin about making an EV dragster. He has tons of stuff in his workshop from his days working for ABB, GE, and Allan Bradley. I do know he has had some experience with EV testing as some of his guys installed a dyno for some outfit in Wisconsin or Michigan that was building EV car motors, I believe they were using wheel motors. He did tell me they were bought out by another company now. Anyway, he may be able to answer some questions but I'm not familiar with the problems yet. I was just planning on buying this stuff but it now looks like I may need him to build it for me IF I knew what to build.


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## major (Apr 4, 2008)

2cycle said:


> (mostly in the 1000's of hp)


That would do nicely


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## caspar21 (Apr 8, 2009)

Tesseract said:


> And yeah, I was kind surprised that Z2K went so quick, and at the Buy It Now price of $6500, even. Hmmm... even if we did only sell 4 or 5 2kA controllers we could just about cover the incremental development cost.


i think 4 to 5 models sold is very conservative.
the drag community is taking notice of how fast electrics are going
and more and more are looking into them. the web site hits on EV dragsters are starting to jump fast.

racing groups will pay much more than your average backyard commuter converter! if only for that extra half second.


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## CroDriver (Jan 8, 2009)

2cycle said:


> Can somebody supply me with some actual numbers on what's "wanted" from a controller, I'm talking to make big hp for street or strip. While I'm just getting into this EV stuff I didn't realize it was so hard to find the controller to make it all work. If I can get some real info on whats needed I will run it by my father, he specializes in drive systems for AC and DC motors, although he doesn't ususally deal with small motors (mostly in the 1000's of hp) he may be able to steer us in the right direction or even build it. I brought it up to him this weekend while we were hanging some drywall at my house and just chattin about making an EV dragster. He has tons of stuff in his workshop from his days working for ABB, GE, and Allan Bradley. I do know he has had some experience with EV testing as some of his guys installed a dyno for some outfit in Wisconsin or Michigan that was building EV car motors, I believe they were using wheel motors. He did tell me they were bought out by another company now. Anyway, he may be able to answer some questions but I'm not familiar with the problems yet. I was just planning on buying this stuff but it now looks like I may need him to build it for me IF I knew what to build.



Look at the Zilla HV Z2K spec's: http://cafeelectric.com/zilla.php?z...9&zenAdminID=74843299a81299efa3d61314338bea89


This is pretty much the best controller ever. The price should be under $5.000


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## toddshotrods (Feb 10, 2009)

caspar21 said:


> i think 4 to 5 models sold is very conservative.
> the drag community is taking notice of how fast electrics are going
> and more and more are looking into them. the web site hits on EV dragsters are starting to jump fast.
> 
> racing groups will pay much more than your average backyard commuter converter! if only for that extra half second.


What he said ^^^

That's the point I've been trying to make. The current DIY EV community is a strange dichotomy of green and/or economy minded transportation and racers. The two don't really mix, and their needs are on opposite ends of the spectrum. Making things more complicated for the racers is the fact that the market is dominated by the green/economy side.


I'm planning on a LiFePo4 pack, controller with Zilla-type capabilities, and full race built motor. I have no illusions about doing any of it on a budget. If I had continued with my plans to build a comparable ICE version of my current project, I would have to spend $10-15K for an engine, $3-5K for a race-ready electronic o/d transmission, $3-5K for the EFI ECU, $1K for the cooling system, $1-2K for the exhaust, etc. I didn't convert to electric to save money...


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## 2cycle (Jul 2, 2009)

I'll show him this info and see what he says. Who knows, this might be easier than we think OR it could be a huge mess and we'll have to wait for the Zilla's to come back.


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## Bowser330 (Jun 15, 2008)

Tesseract said:


> I *think* virtually all of those were Z1KHV models; dunno how the waiting list broke down between the 1kA and 2kA models.
> 
> That said, keep in mind the 1kA and 2kA ratings are strictly a short-time peak and that the continuous current ratings are a more modest ~350A and ~700A respectively.
> 
> And yeah, I was kind surprised that Z2K went so quick, and at the Buy It Now price of $6500, even. Hmmm... even if we did only sell 4 or 5 2kA controllers we could just about cover the incremental development cost.


Tess, sir, you make a good point...

I think another reason why the Z2K is being used is for the 700A continuous it offers...

YES! please make the "racing" controller (300V+ 1000A+ continuous) your next project once you start to generate revenue from your 200V+1000A continuous model...

Hows the beta testing going? 


Notes:

JW has said that he dials down to 1500A for the White Zombie
DB's S10 at 393V can only pull max 1600A per the Cafe Electric website. (see link)

http://cafeelectric.com/zilla.php?z...9&zenAdminID=74843299a81299efa3d61314338bea89

Does anyone know how many seconds the Zilla2KHV can sustain 1500A, under 100% WOT? (in a system that is 350V+)

Todds,

The 200V 1000A (cont) unit will definately be the controller get for one fast street machine...

We need higher voltage because we need more torque at higher speeds (rpm)...

The higher voltage almost flattens the rpm line more to allow more torque without dropping RPM...

HP = TQ x RPM/5252

1000A in a kostov-13 = 400ftlbs

If Evnetics 200V can sustain 1000A up to 2000rpm, then this confirms what I expect a graph would show about a Warp-13 with 360V and 1000A.

1000A(400ftlbs) @ ~3000rpm... = 228HP hmmmm


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## Tesseract (Sep 27, 2008)

Bowser330 said:


> I think another reason why the Z2K is being used is for the 700A continuous it offers...


Well, we already beat that rating like a red-headed stepchild... 




Bowser330 said:


> YES! please make the "racing" controller (300V+ 1000A+ continuous) your next project once you start to generate revenue from your 200V+1000A continuous model...


The 1kA controller is already theoretically capable of operating at 345V max _it just hasn't been tested at that high of a voltage yet!_ Note, just like Cafe Electric will be dialing down the maximum current slightly at the highest voltage... probably to around 900A (and we will limit the maximum switching frequency, which otherwise is somewhat fluid depending on controller temp, current and duty cycle, to 8khz (which is pretty much still inaudible)).

I'm throwing together a quick-n-dirty 0-350V/30A charger this week to hopefully bump the test pack up to 24 batteries... Then the motor beatings will begin in earnest.




Bowser330 said:


> Hows the beta testing going?


Very well - I see you asked for an update in the other thread... guess it's time to trot out the dog-and-pony show again.




Bowser330 said:


> Does anyone know how many seconds the Zilla2KHV can sustain 1500A, under 100% WOT? (in a system that is 350V+)


I've been wondering that myself... the closest we get to an answer is the data on plasmaboyracing.com (that graph Qer reposted here).


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## CroDriver (Jan 8, 2009)

900 Amps @ 350V would be great. Two of these on a dual motor would be great for racing. 

Would it be possible to do a series/parallel shift with two controllers?


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## Qer (May 7, 2008)

CroDriver said:


> Would it be possible to do a series/parallel shift with two controllers?


Nope. There's no plan on making the controller cooperate with a brother, simply because there's no reliable way we could sync them and if they're not perfectly synced odds are that at least one controller will go *BOOM!* _sissle_ *tinkl* pretty immediately. Ok, if you're planning to race you should be prepared for high maintenance, but I also believe that the whole point of racing is to win and that's gonna be hard if the race's over after a meter or three. 

However, it's possible to run one controller per motor of course. It's still "only" gonna give you 1kA per motor, but keep them cool and they'll continue to give 1kA per motor as long as the battery pack can sustain it...

EDIT: Come to think of it. They might actually not go *BOOM!* _sissle_ *tinkl*, I thinkthey'll go *ERROR-ERROR-ERROR* more or less as soon as you touch the throttle...


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## Bowser330 (Jun 15, 2008)

Tesseract said:


> Very well - I see you asked for an update in the other thread... guess it's time to trot out the dog-and-pony show again.


I by no means am trying to rush you for an update, just really interested in the information you guys have been sharing with us..



> I've been wondering that myself... the closest we get to an answer is the data on plasmaboyracing.com (that graph Qer reposted here).


John's words about that graph....



> For those who don’t want to decipher the graphs, it appears that during the first 4-5 seconds of discharge @ 1100 amps, the pack kneels to about 235 volts. That’s 258.5 kw of power, or a real delivered 346 battery hp! The last part of the run, the batteries do sag lower to 162.4 volts.


Another quote, atleast we know the raptors 1200 only lasts a few (3?)seconds....



> The DCP 1200 Raptor was powerful, but after a few seconds, its 1200 amps ramped down to I suspect, 800 amps or so…never broke a tranny under it’s rein. The Z1K, though rated 200 amps lower, evidently, has more continuous power delivery….witness the two 4 speed trannys it’s eaten in the last year!


These probably dont help much....with all the racers out there with a 2KHV, killacyle, white zombie, Smokescreen, current eliminator, etc...you would think it would be posted somewhere....


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## toddshotrods (Feb 10, 2009)

Bowser330 said:


> ...Todds,
> 
> The 200V 1000A (cont) unit will definately be the controller get for one fast street machine...
> 
> We need higher voltage because we need more torque at higher speeds (rpm)...


Why are you saying that to me? I want a 400v/2000amp controller. If it's because I said don't count Tesseract and Qer's product out, I was refeering to the fact that they are getting Zilla-like numbers in the first rounds of testing - their first model! Remember, Zilla didn't start off with the 2K-HV. If their first model is this impressive, imagine what monster they can build if they are so inclined. If enough racers come knocking on their doors with plastic cards in hand, they may just do something that makes the Zilla 2K-HV the _first_ great controller, instead of the only...


----------



## Batterypoweredtoad (Feb 5, 2008)

Quote:
For those who don’t want to decipher the graphs, it appears that during the first 4-5 seconds of discharge @ 1100 amps, the pack kneels to about 235 volts. That’s 258.5 kw of power, or a real delivered 346 battery hp! The last part of the run, the batteries do sag lower to 162.4 volts.

?????? -from the graph I'm reading the batteries never drop below 200v?

My take on the graph:

1st-The first part of the run with the motors in parallel the current limit is engaged most of the time with the motor voltage being manipulated to try to stay around the 1k amp limit. The controller gradually homes in on the 1k amp mark and drops slightly below the mark and full pwm is achieved at 110v per motor.

2nd-the parallel/series shift takes place and now at about 50% pwm each motor is getting 110v and pulling around 800a each. The pwm increases through the end of the run hitting about 75% at the end of the run feeding a regulated 170V or so to each motor causing the run to end with about 900Amps total split between the motors.

It seems like they pretty much bounced off of or exceeded the 1k amp controller limit almost the entire run. It looks like the batteries did fine.

I now restate my arguement that they could use a transmission with a 2/1 and 1/1 gear selection and run closer to 1k amps per motor the entire run and be faster.


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## Bowser330 (Jun 15, 2008)

toddshotrods said:


> Why are you saying that to me? I want a 400v/2000amp controller. If it's because I said don't count Tesseract and Qer's product out, I was refeering to the fact that they are getting Zilla-like numbers in the first rounds of testing - their first model! Remember, Zilla didn't start off with the 2K-HV. If their first model is this impressive, imagine what monster they can build if they are so inclined. If enough racers come knocking on their doors with plastic cards in hand, they may just do something that makes the Zilla 2K-HV the _first_ great controller, instead of the only...


Relax...Thats what I meant, the 200V 1KA product is great (just look at my posts in the threads about the new controller, i am really excited about it) and it will make a really fast STREET machine, however (forgot to put that word in) I am with you, I want higher voltage like what the S10 has to make something that will be a fast DRAG machine...


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## toddshotrods (Feb 10, 2009)

Bowser330 said:


> Relax...Thats what I meant, the 200V 1KA product is great (just look at my posts in the threads about the new controller, i am really excited about it) and it will make a really fast STREET machine, however (forgot to put that word in) I am with you, I want higher voltage like what the S10 has to make something that will be a fast DRAG machine...


Oh, my bad - feathers unruffled.  In retrospect, I do think it's funny that I had such an issue with being associated with fast street machines. 

Whatever route is taken (direct-drive, transmission, converted street car, purpose-built racer, etc) the controller is the one need we share in common. So, are the Zilla 2K-HV's specs still the benchmark we're seeking, or is there going to be a need for something even more substantial. In other words, if Cafe Electric was still (in full production) cranking out controllers today, would they just concentrate on incremental improvements for the big guy, or would they see the need to up the ante in some way to meet the needs of the fast guys?


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## Bowser330 (Jun 15, 2008)

toddshotrods said:


> Oh, my bad - feathers unruffled.  In retrospect, I do think it's funny that I had such an issue with being associated with fast street machines.
> 
> Whatever route is taken (direct-drive, transmission, converted street car, purpose-built racer, etc) the controller is the one need we share in common. So, are the Zilla 2K-HV's specs still the benchmark we're seeking, or is there going to be a need for something even more substantial. In other words, if Cafe Electric was still (in full production) cranking out controllers today, would they just concentrate on incremental improvements for the big guy, or would they see the need to up the ante in some way to meet the needs of the fast guys?


I would say yes, I think the ZIlla 2KHV is the benchmark many car builders want, and controller builders have in mind...I think once many controller builders see how much they need to invest in high quality robust parts and the labor, to construct and test a similar potent controller, the idea never becomes reality. Although there are a few out there that have some products none are as tested and proved as the ZILLA is..Evnetics will be something that I feel will do well in the market, powerful controller and they are very personable and open with the development, the ups and the downs..which makes the beta testers and the future customers more comfortable...

If 400V and 1600A is enough to make a 3300 lb truck, with 7.5" tires, do 11.083 in the qrtr...then a lighter more aerodynamic car with wider tires (and the equivalent M+C+B setup) could possbily break into the 10s...Personally thats all im looking for...


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## notnull (Jul 30, 2008)

I haven’t see anyone use a LiPo pack for a drag car. I have used the LiPo’s for years in my R/C planes with no problems. Obviously, they can “vent with flame”. I have only read about this in instances where they were over-charged and I have personally charged LiPo packs hundreds of times and never had an incidence. So, just to get this out of the way, let’s assume they are safe to use in a drag racing application and just see what kind of pack could be built.

Hobby city sells 6s1p – 5000 mah packs for $59.99, rated at 20C continuous discharge. 900g.

You could buy 120 of these packs for $7,200. Arrange them in 6 series 20 parallel configuration. 

This gives you a 133.2V nominal (3.7 per cell) 100Ah pack that weighs 240lbs and is rated at 2000A continuous discharge. 

I mention these because the price has really come down and many of the electric bicycle guys are switching to them instead of a LiFePO4 battery, I still use A123 on my bicycle. 

I wouldn’t want to be the first one to melt my car with these but I think it is an interesting option.

Steve


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## DavidDymaxion (Dec 1, 2008)

http://www.proev.com uses LiPos.

Let's compare to A123 systems: 2.3 Ahr cells are about $15 each. The cells you mention are about $10 each, but have about twice the weight and twice the Ahr. Here's the big difference that I think leads the drag racers to use them: A123s are spec'd for 35C (70 amps for 2 minutes) and 50C pulse (120 amps for 10 seconds). Those are just the specs -- Bill Dube of http://www.killacycle.com fame pulls 70C (170 amps) from each cell!

So if you want power, the A123 systems batteries are better for a comparable $/kW price, and have a much better power-to-weight ratio. If you want the cheaper pack for range ($/Ahr), the LiPos win.

Also, the proev folks have popped a few batteries. At one point (might still be true) Bill Dube said the Killacycle hadn't lost a battery yet.



notnull said:


> I haven’t see anyone use a LiPo pack for a drag car. I have used the LiPo’s for years in my R/C planes with no problems. Obviously, they can “vent with flame”. I have only read about this in instances where they were over-charged and I have personally charged LiPo packs hundreds of times and never had an incidence. So, just to get this out of the way, let’s assume they are safe to use in a drag racing application and just see what kind of pack could be built.
> 
> Hobby city sells 6s1p – 5000 mah packs for $59.99, rated at 20C continuous discharge. 900g.
> 
> ...


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## toddshotrods (Feb 10, 2009)

Are A123s available to the general public now? If so, where?


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## DavidDymaxion (Dec 1, 2008)

Most racers are breaking apart DeWalt tool battery packs, and assembling their own EV packs. You absolutely must have a cell level bms. There is someone that is assembling them into 12 V batteries for a lightweight racing battery, but my apologies I don't remember the name.


toddshotrods said:


> Are A123s available to the general public now? If so, where?


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## JRP3 (Mar 7, 2008)

This guy http://www.evconsultinginc.com/34ford.html is using these batteries http://www.ev-battery.com/ which are a bit STIFF on pricing http://www.ev-battery.com/prices.html
Wakinyantanka here on the forum was selling A123 modules, don't know if he's still doing it or not http://www.diyelectriccar.com/forums/showthread.php?t=29007


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## toddshotrods (Feb 10, 2009)

A _bit_ stiff eh?! $52,440 for a 360 volt max race pack! 

With that, I would probably be into over $75K, for the whole package (built motor, controller, battery pack, bms, charger, wiring, etc.)

If I did, would I truly be getting at the same performance they're getting with cells directly from A123 on the KillaCycle bike? Honestly, I like the idea of paying for them up front over a sponsorship deal because I can go home when I want to, but for that price they MUST deliver on the promise.


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## Bowser330 (Jun 15, 2008)

notnull said:


> I haven’t see anyone use a LiPo pack for a drag car. I have used the LiPo’s for years in my R/C planes with no problems. Obviously, they can “vent with flame”. I have only read about this in instances where they were over-charged and I have personally charged LiPo packs hundreds of times and never had an incidence. So, just to get this out of the way, let’s assume they are safe to use in a drag racing application and just see what kind of pack could be built.
> 
> Hobby city sells 6s1p – 5000 mah packs for $59.99, rated at 20C continuous discharge. 900g.
> 
> ...


What about charge amps? I read that some of these li-pos can only tolerate 5A or less


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## Overlander23 (Jun 15, 2009)

LiPo's in the RC world can handle 1C... anything less helps extend life a little more. 



Bowser330 said:


> What about charge amps? I read that some of these li-pos can only tolerate 5A or less


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## Bowser330 (Jun 15, 2008)

Overlander23 said:


> LiPo's in the RC world can handle 1C... anything less helps extend life a little more.


so a 5000mah pack can only charge at 5A, but less is better for life...

Seems pretty low compared to the A123 packs...or event he LifePo4 packs...


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## Overlander23 (Jun 15, 2009)

I dunno... how fast are people charging their A123 or LiFePO4 packs? 1C is an hour (it actually ends up being a little more to top it up completely.) When you get into large traction packs, and your capacity starts to go up, you're limited to what your charging source can provide anyway.

Personally, I don't think the additional cost outweighs the density advantage... but in the drag/race world, cost issues sometimes become secondary. LiPO is also capable of delivering 25C continuous discharge with up 50C burst. That's significantly better than LiFePO4 if you need that kind of capability.

Actually just discovered that Thunder Power RC has a 40C (80C burst) cell that can be charged at 6C with their charger and balancer. Not cheap, though.



Bowser330 said:


> so a 5000mah pack can only charge at 5A, but less is better for life...
> 
> Seems pretty low compared to the A123 packs...or event he LifePo4 packs...


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## Bowser330 (Jun 15, 2008)

Overlander23 said:


> I dunno... how fast are people charging their A123 or LiFePO4 packs? 1C is an hour (it actually ends up being a little more to top it up completely.) When you get into large traction packs, and your capacity starts to go up, you're limited to what your charging source can provide anyway.
> 
> Personally, I don't think the additional cost outweighs the density advantage... but in the drag/race world, cost issues sometimes become secondary. LiPO is also capable of delivering 25C continuous discharge with up 50C burst. That's significantly better than LiFePO4 if you need that kind of capability.


good point, I guess if the drag racer isn't looking to quickly charge their pack in between runs its a better racing pack...Lighter weight with more C output...


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## toddshotrods (Feb 10, 2009)

Bowser330 said:


> ...if the drag racer isn't looking to quickly charge their pack in between runs...


That's going to be necessary. You want to have as much battery for the next pass as you had for the last one.


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## Bowser330 (Jun 15, 2008)

toddshotrods said:


> That's going to be necessary. You want to have as much battery for the next pass as you had for the last one.


If price wasnt really an option, maybe you could have a quick disconnect LIPO pack that you could replace for the next run while the other replacement packs were charging...


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## caspar21 (Apr 8, 2009)

hrmm.. how much time do you have between runs?
it has to be more than the 20 mins required to charge lipos.

white zombie has said he charges in under 15 mins.

how much do you expect to use? 10c out, 1 c in..
for a 180 Ahr cell that is 1800 amps out in around 10 secs 

thats what? 10 sec * 10 = 100 seconds(+ another 20 secs for losses)

drag is such a short duration that not much total energy goes out.

for bracket racing i would start with a pack only partially charged as the top % of the pack charges slowly. then meter what goes out and what goes in.


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## Overlander23 (Jun 15, 2009)

Yeah, I'm curious to know how much power it is, too... 

This is probably the completely wrong way of figuring this out (and very elementary), but... In the simplest, perfectly efficient, terms is this correct (assuming a completely random scenario)?

Desired power output 500kw (670hp) for 10 seconds.

With perfect efficiencies this can be generated with 2000amps @250v.

To generate that much power for 10 secs consumes 5.5AH ((2000/360) = (amps/10sec or 1/360th of an hour))

Now you have to multiply by a bunch of inefficiencies... if this is anywhere near a baseline calculation, it's not as much as I would have expected.

Or am I way off...


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## Drew (Jul 26, 2009)

Overlander23 said:


> I dunno... how fast are people charging their A123 or LiFePO4 packs? 1C is an hour (it actually ends up being a little more to top it up completely.) When you get into large traction packs, and your capacity starts to go up, you're limited to what your charging source can provide anyway.
> 
> Personally, I don't think the additional cost outweighs the density advantage... but in the drag/race world, cost issues sometimes become secondary. LiPO is also capable of delivering 25C continuous discharge with up 50C burst. That's significantly better than LiFePO4 if you need that kind of capability.
> 
> Actually just discovered that Thunder Power RC has a 40C (80C burst) cell that can be charged at 6C with their charger and balancer. Not cheap, though.


A123 cells are capable of a continuous 26C and a burst 50c. You can also charge them at 4C

The other benefit is no pack fires, I know of a solar car team who I did a little bit of work for who got the opportunity to redesign their car from the ground up for abusing something like 200whrs of Lipos... The fire reached over 1000 degrees C, I'd shudder to think what happened if you put 2kWh or more in the same place.


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## Bowser330 (Jun 15, 2008)

where can the most inexpensive 123 Cells be found?

25C cont. 50C burst...how many seconds does burst stand for?

A pack of just 80AH would be able to discharge 2000A cont!


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## Drew (Jul 26, 2009)

http://a123systems.textdriven.com/product/pdf/1/ANR26650M1A_Datasheet_APRIL_2009.pdf

Thats the spec sheet for them...


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## caspar21 (Apr 8, 2009)

Bowser330 said:


> where can the most inexpensive 123 Cells be found?
> 
> 25C cont. 50C burst...how many seconds does burst stand for?
> 
> A pack of just 80AH would be able to discharge 2000A cont!



who is cheapest is changing daily.. look locally first. then look (with some risk) overseas.


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## Bowser330 (Jun 15, 2008)

wakinyantanka

was selling the cells for 856$/kwh 

he was saying 30C cont, 50+C pulsed

I still dont know what pulsed exactly means...

how many C for 11 seconds? 40?


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## Drew (Jul 26, 2009)

According to the A123 spec sheet that I linked directly above the 120A or 50C rating is for 10 seconds.


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## Dennis (Feb 25, 2008)

Series wound motors are torque monsters for the current they draw versus other DC motor types; so they get out of the hole very quickly, but they also have a downside to them in which their torque curves fall of at a exponential rate as shown here:










In theory a series wound motor has infinite torque that is asymptotic to the Y-axis and infinite torque range into infinite RPM's that is asymptotic to the X-axis. In the real world a series wound motor is current limited and their are other factors like magnetic saturation of the iron that limit torque to a defined value and the extent it reaches out is limited to mechanical design limits that should not be exceeded or friction. But what matters here in this graph is the shape. The shape of the torque curve is what makes a series wound motor feel as though it is running out of oomph as the dragster is plowing down the 1/4 mile track.

Pick some ICE torque curve and superimpose it onto a series wound motor torque curve. Note that at zero RPM up until the ICE's torque is equal to the series wound motor at some RPM point that the series wound motor has torque that is greater than the ICE at those RPM's, but then as we go past the point where they are equal, the ICE starts to have the torque advantage and therefore will continue to have acceleration where as the series wound motor has reached a stable operating point and simply cannot accelerate the dragster any further unless more voltage is applied to the motor.

Their are many tricks used to combat this like taking 2 or more smaller motors (such as L91-4003's) that are shaft coupled together that need lots more RPM's to generate the same back EMF (voltage generated by motors) compared to one big motor for its lower RPM's, and have the motors start off as wired as a series circuit to each other to get max torque (both motors receive the same current) off the line then have them switched to parallel circuit at the sweet RPM spot so that they both receive the same voltage causing the motors operating torque point to increase, leading to acceleration till the new stable operating point is reached.


Killacycle is a fine example of this method being used.


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## Tesseract (Sep 27, 2008)

Dennis said:


> ...have the motors start off as wired as a series circuit to each other to get max torque (both motors receive the same current) off the line then have them switched to parallel circuit at *the sweet RPM spot* so that they both receive the same voltage causing the motors operating torque point to increase, leading to acceleration till the new stable operating point is reached.


I think this is worth hashing out a little more, so first off, I'm curious as to how you would determine that RPM?


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## major (Apr 4, 2008)

Tesseract said:


> I think this is worth hashing out a little more, so first off, I'm curious as to how you would determine that RPM?


Hi Tesseract,

If I'm not mistaken, the series to parallel switch is timed based on current, not RPM. For instance, using a 2000 A current limit, the S/P switch will occur at 1000 A, then go back to the 2000 A limit on the controller, each motor getting 1000 A. That way the total torque from the pair of motors is the same before and after the S/P switch and power from the controller is maximized.

Regards,

major


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## DavidDymaxion (Dec 1, 2008)

It's 2 to 3 times the complexity, but I had the idea it would be neat to have a controller that would rapidly switch between series and parallel mode (at pwm rates). This would give you a fatter torque curve, allowing you to draw the full 2000 Amps until full parallel mode, rather than ramping down from 2000 Amps to 1000 Amps.

Now I'll argue against it. This only helps until the s/p transition. In drag racing the launch is all important, but if you can already roast the tires to that point, more torque isn't going to help. For road racing or land speed, gears will give you all the launch you need, and the launch isn't as critical. So this would be an expensive niche for an all out drag racer, might as well go AC!

So here's a thought for a possible compromise (thanks to Lee Hart):
Everything in series to start
Switch the fields to parallel, keep the armatures in series
Switch the fields to series, put the armatures in parallel
Switch the fields to parallel

I haven't worked out the optimal shift points, or if every state is worth it, but in theory this would provide a fatter torque curve. You'd likely need a motor with interpoles to avoid the arcy sparky fun.



Dennis said:


> Series wound motors are torque monsters for the current they draw versus other DC motor types; so they get out of the hole very quickly, but they also have a downside to them in which their torque curves fall of at a exponential rate as shown here:
> 
> 
> 
> ...


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## major (Apr 4, 2008)

DavidDymaxion said:


> It's 2 to 3 times the complexity, but .....
> So here's a thought for a possible compromise (thanks to Lee Hart):
> 1. Everything in series to start
> 2. Switch the fields to parallel, keep the armatures in series
> ...


Hi David,

Step 2 is just a 50% field weakening. Step 3 is a 200% field (strengthening).

You're talking about high voltage systems running currents of 1000 to 2000 A. This field control is going to be of little consequence due to the fact that the motor is well into saturation. Except for some additional sparks, I doubt you'd notice anything besides the lag during the switch.

Regards,

major


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## Qer (May 7, 2008)

major said:


> If I'm not mistaken, the series to parallel switch is timed based on current, not RPM. For instance, using a 2000 A current limit, the S/P switch will occur at 1000 A, then go back to the 2000 A limit on the controller, each motor getting 1000 A. That way the total torque from the pair of motors is the same before and after the S/P switch and power from the controller is maximized.


Yep, that's what I've figured too, now I only have to implement it + figure out when to drop back to series again...


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## major (Apr 4, 2008)

Qer said:


> + figure out when to drop back to series again...


How about the next day


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## Dennis (Feb 25, 2008)

> If I'm not mistaken, the series to parallel switch is timed based on current, not RPM. For instance, using a 2000 A current limit, the S/P switch will occur at 1000 A, then go back to the 2000 A limit on the controller, each motor getting 1000 A. That way the total torque from the pair of motors is the same before and after the S/P switch and power from the controller is maximized.


Now that I think about that is how they do this for the Zilla's. This is the direct way to relate torque to current. My method would do it indirectly by (Vsupply - VGen)/ Ra, were Vgen would be dependent on motor RPM's. There is more than one way to skin a cat but one method is more efficient than another, and that current measurement method is a better way to do it!


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## Juiced (May 2, 2009)

*What's holding the EV drag racers back?*


Money....... 

100 Years of ICE technology versus battery technology that changes monthly. 

A controller that can be programmed to vary the volts/amps as the motor/you want during a pass to maximize speed/torque.

A programmable BMS that can handle the volts/amps we need.

MMMMMMmmmmmmmmmmmm a controller/BMS combo unit? 


" these are a few of my favorite things....."

Drag Race Ed


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## EVComponents (Apr 20, 2009)

DavidDymaxion said:


> John Wayland recently reported the Tesla is relatively sluggish up to about 30 mph, and then really takes off 30 to 60 mph. (A sluggish that still beats most cars!)


I can report that the Tesla Roadster sweet spot is between 30 mph and 70 mph. It is absolutely brutally fast and you won't even be able to reach the radio (as a passenger) during that portion of the acceleration.

It is actually perfect as a daily driving vehicle because in that speed range is where you spend the bulk of your driving day.


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## Bowser330 (Jun 15, 2008)

EVComponents said:


> I can report that the Tesla Roadster sweet spot is between 30 mph and 70 mph. It is absolutely brutally fast and you won't even be able to reach the radio (as a passenger) during that portion of the acceleration.
> 
> It is actually perfect as a daily driving vehicle because in that speed range is where you spend the bulk of your driving day.


So how do you think a Tesla woul compare to a GTM kitcar with 11" HV motor and Zilla 2K? with 300V + 200AH pack?


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## caspar21 (Apr 8, 2009)

Bowser330 said:


> So how do you think a Tesla woul compare to a GTM kitcar with 11" HV motor and Zilla 2K? with 300V + 200AH pack?


the tesla would do it much longer. 11" warp is not designed for that kind of voltage.


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## Bowser330 (Jun 15, 2008)

its not your standard warp 11 caspar...thats why i wrote "11" HV"

High Voltage...its a new motor that Netgain has created that when advanced is advertised to handle up to 336V..oh and have a max of 9000rpm...

The White Zombie, with a single *built* 11" kostov motor was able to draw 620A (@6000+rpm) from the 336V pack (sagged to 250V)...with a Zilla 1K!!

Maybe a setup with dual 11" motors...with dual 1000A continuous controllers....

600ftlbs torque continuous....hmmmmm?


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## AmpEater (Mar 10, 2008)

We only have preliminary data on the warp 11" hv so far....nobody has actually caught one in the wild, so its too soon to tell. But the specs so far do look incredibly promising. 9000 rpm means you can use a high ratio rear end for excellent torque multiplication while still achieving a high top speed. The high voltage should allow for a very wide torque band.

On a matchup between a Tesla and a DC kitcar of the same weight with a warp 11" with a zilla 2k my money would be on the DC setup. Certainly on the low end, around town zippy ness, etc. On the high end the Tesla might still have an advantage....but without first-hand user experiences it's too early to know. Bang for buck there wouldn't be any competition.


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## Bowser330 (Jun 15, 2008)

AmpEater said:


> We only have preliminary data on the warp 11" hv so far....nobody has actually caught one in the wild, so its too soon to tell. But the specs so far do look incredibly promising. 9000 rpm means you can use a high ratio rear end for excellent torque multiplication while still achieving a high top speed. The high voltage should allow for a very wide torque band.
> 
> On a matchup between a Tesla and a DC kitcar of the same weight with a warp 11" with a zilla 2k my money would be on the DC setup. Certainly on the low end, around town zippy ness, etc. On the high end the Tesla might still have an advantage....but without first-hand user experiences it's too early to know. Bang for buck there wouldn't be any competition.


well said...

I guess my hopes are just high for this new product...


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## AmpEater (Mar 10, 2008)

Bowser330 said:


> well said...
> 
> I guess my hopes are just high for this new product...


Thanks 

Same here...I'm kind of kicking myself for buying a transwarp 11" now. Wish I had known about the HV offering coming soon. 

It might be a game-changer. Neutrally timed at 288v with interpoles, combined with a regen enabled warp-core controller (coming soon?)....I think everyone will have a new favorite combo to play with.

I can hardly wait


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## Bowser330 (Jun 15, 2008)

AmpEater said:


> Thanks
> 
> Same here...I'm kind of kicking myself for buying a transwarp 11" now. Wish I had known about the HV offering coming soon.
> 
> ...


NICE.. Warp-11, what controller will you be getting to pair it up with?

Warp-core? 156V 1000A??

The Soliton1 can go up to 192V, the new max voltage for your Warp-11 and can produce 1000A *non-stop* with water cooling....

1000A with your Warp-11 is about 300ftlbs!


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## 280z1975 (Oct 2, 2008)

Bowser330 said:


> snip ...
> 
> The Soliton1 can go up to 192V, the new max voltage for your Warp-11 and can produce 1000A *non-stop* with water cooling....
> 
> ... snip


From the rebirthEV website:

[h4]Performance: [/h4]


 *1000 Amps:* Soliton1 has a continuous current rating with liquid cooling of 1000A. Running on the integrated cooling fans only, 1000A is typically available for 15-20 seconds before thermal derating kicks in.
 *1400 Amps:* Soliton1 can be factory setup for 1400A race operation upon EVnetics' approval of your application (special racing warranty applies).
 *340 Volts:* 8 to 340 Volts maximum pack voltage. The full charge pack voltage must be limited to 340 Volts.
So it's 340 Volts max (and has been rumored to be working on a regen feature) ... I am now torn between the two as I had given up on the Zilla ever coming back. EV Componets have really stepped up in the last couple of months to really bring better quality stuff to the DIY world.

-Gregg-


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## Bowser330 (Jun 15, 2008)

280z1975 said:


> From the rebirthEV website:
> 
> [h4]Performance: [/h4]
> 
> ...


Right on...my post may have been unclear...I was trying to tell him that it can go higher than the 156V and be perfect for the max of his motor, 192V...not that it was limited to 192v...


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## 280z1975 (Oct 2, 2008)

Bowser330 said:


> Right on...my post may have been unclear...I was trying to tell him that it can go higher than the 156V and be perfect for the max of his motor, 192V...not that it was limited to 192v...


Got ya on the 192v ... but I would think twice about going to 192v, with the Solition1 and a lead foot (which is what would happen in a 240z like AmpEater has) as the motor noise I heard from the beta-testing video from the build thread of the Solition1 was not good ... you would have to limit the current via program screen to keep you from toasting that 11" motor ... the 11"HV on the other hand, *might* be the perfect match with the high power controlers.

Currently I'm stashing away a bit each month for my build which will be at the moment 300+V Litium pack, the 11"HV and the Solition1 ... together I hope to go direct drive. It won't be the fastest it can off the line or have the highest top end, but it will be a good all around car which can MOVE!


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## caspar21 (Apr 8, 2009)

280z1975 said:


> It won't be the fastest it can off the line or have the highest top end, but it will be a good all around car which can MOVE!


that has to be the tastiest sounding DC combo i have heard yet!]


i would love to see a torque/rpm mapping of the HV 11" on some high voltage.


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## Bowser330 (Jun 15, 2008)

caspar21 said:


> that has to be the tastiest sounding DC combo i have heard yet!]
> 
> 
> i would love to see a torque/rpm mapping of the HV 11" on some high voltage.


+10000

The highest voltage power graph i can find at the moment is this Kostov-11" @ 192V....(linked) 

http://kostov-motors.com/files/productattachments/da0012f5e806b95241ea09d19be9abe3_11-192V.pdf

This video has rekindled my mission to build a lightweight EV....thought I would share....

http://www.dpccars.com/car-videos-09/08-06-09page-Corvette-ZR1-vs-AC-Cobra-Mk6.htm

AC Cobra weighs 2260lbs and has 430hp (Stock Corvette LS3 OEM engine)


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## Batterypoweredtoad (Feb 5, 2008)

That kostov graph makes me sad. If I am reading correctly, the Kostov is making about 132 ft lbs of torque and 82 hp at ~520amps, 192V and 3800 rpm. If the 11HV behaved exactly the same it would put out 144hp at 338V, 520 amps, and 6700rpm. Nice but not direct drive drag racer fast. Am I doing my math wrong?


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## DavidDymaxion (Dec 1, 2008)

You can go to http://www.plasmaboyracing.com and get lots of details. Short story is drag racer John Wayland put alot more than spec amps and volts through his Kostov -- 336 Volt pack and 1200+ Amps. Do keep in mind he also eventually burned up his motor!


Batterypoweredtoad said:


> That kostov graph makes me sad. If I am reading correctly, the Kostov is making about 132 ft lbs of torque and 82 hp at ~520amps, 192V and 3800 rpm. If the 11HV behaved exactly the same it would put out 144hp at 338V, 520 amps, and 6700rpm. Nice but not direct drive drag racer fast. Am I doing my math wrong?


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## CroDriver (Jan 8, 2009)

DavidDymaxion said:


> You can go to http://www.plasmaboyracing.com and get lots of details. Short story is drag racer John Wayland put alot more than spec amps and volts through his Kostov -- 336 Volt pack and 1200+ Amps. Do keep in mind he also eventually burned up his motor!



He did put 400 kW in the Kostov but the question is how much did he get out of it?

He always claims that his car has 250hp. 

The efficiency of DC motors drops like a stone under such loads. I wouldn't be surprised if it was under 50% at 300+V and 1200Amp


----------



## Tesseract (Sep 27, 2008)

CroDriver said:


> He did put 400 kW in the Kostov but the question is how much did he get out of it?


THAT is the question!

When we ran our WarP 9 at 100kw (100-110V at the motor and 1000A) we got about 80kW out according to the dyno... 

The same 100kW through the Kostov 9, though, resulted in just under 70kW out.

So a difference of 10 percentage points in efficiency at the 1000A level. To be fair, though, the Kostov is wound for a higher voltage and lower current while the WarP is the opposite, so it's possible that if I applied, say, 150V and 667A through the Kostov I would have gotten just as good efficiency from it (too bad we blew it up on the last 1000A run so, no more testing that motor  ).


----------



## Bowser330 (Jun 15, 2008)

DavidDymaxion said:


> You can go to http://www.plasmaboyracing.com and get lots of details. Short story is drag racer John Wayland put alot more than spec amps and volts through his Kostov -- 336 Volt pack and 1200+ Amps. Do keep in mind he also eventually burned up his motor!


There was a time when John Wayland ran the Whitezombie with a single *built* 11" Kostov with a Zilla 1200A..

John mentions that in one of his 1/4 mile runs (in the 13 sec [email protected] 95.859MPH)...his volts were at 250 and his amps were at 620 near the finish line..that would be 155kw at 6000RPM...

If say you had Siamese 11" Kostov Motors....running in series so each motor gets 300V nominal (sagged down to 250V) and runs 500A to each motor...

250V * 500A =125kw * 2 = 250kw = 340hp @ 6000rpm

A123cells @ 7.5$ each...

91 series 15 parallel = 300V_34.5AH, 96kg total pack weight...

10,238$USD + 1-2K$BMS =~12K$ pack cost...

50C capable, 30C = 1035A (enough for 500 per motor)

*Note: John Wayland's kostov 11" never had an issue while on the track...the "burned up motor" incident happened while he overloaded the motor with current and voltage while show-boating and doing a long burn-out...*


----------



## DavidDymaxion (Dec 1, 2008)

Those are some awesome numbers!

John actually didn't burn up his motor doing a burnout... He was trying to do a burnout but the wheels bit and didn't spin... But it did skid the front wheels. He estimates this went on for 30 to 40 seconds. This is the almost the worst treatment you can give a motor, it was turning very slowly whilst being fed 1200+ Amps! The only thing worse would have been locked rotor.


Bowser330 said:


> There was a time when John Wayland ran the Whitezombie with a single *built* 11" Kostov with a Zilla 1200A..
> 
> John mentions that in one of his 1/4 mile runs (in the 13 sec [email protected] 95.859MPH)...his volts were at 250 and his amps were at 620 near the finish line..that would be 155kw at 6000RPM...
> 
> ...


----------



## Bowser330 (Jun 15, 2008)

point taken, but it was not during racing which is a testament to its strength (granted when *built*)...

In the setup i mentioned above, If you had a 1000A controller that could do series-parallel shifting you would have 1000A into each motor until the shift, which would be a total of 500-600ftlbs of torque...If you had a controller that could handle 2000A well...you know...0-60 in 3 seconds sounds pretty do-able...and with the HP up top...11sec is within range...



DavidDymaxion said:


> Those are some awesome numbers!
> 
> John actually didn't burn up his motor doing a burnout... He was trying to do a burnout but the wheels bit and didn't spin... But it did skid the front wheels. He estimates this went on for 30 to 40 seconds. This is the almost the worst treatment you can give a motor, it was turning very slowly whilst being fed 1200+ Amps! The only thing worse would have been locked rotor.


----------



## Bowser330 (Jun 15, 2008)

I am interested in Kostov-motors.com's 13" with 11" internals...6000rpm capable...with 13" torque profile!...get that sucker up to 300V and a single motor drag-option is available to everyone...


----------



## Batterypoweredtoad (Feb 5, 2008)

Wouldn't the 11hv have more of a 9" torque curve due to the 9" internals and the 13" Kostov with 11" internals have more of an 11" torque curve? 

I think a 11" Kostov with 338 volts with a 500 motor amp limit would probably be able to hold 500 amps through the rpm limit. That would give an interesting power curve that would rise as the rpm increased much like an ICE. Except of course for the fact that full torque would be available at 0 rpm.


----------



## Bowser330 (Jun 15, 2008)

Batterypoweredtoad said:


> Wouldn't the 11hv have more of a 9" torque curve due to the 9" internals and the 13" Kostov with 11" internals have more of an 11" torque curve?
> 
> I think a 11" Kostov with 338 volts with a 500 motor amp limit would probably be able to hold 500 amps through the rpm limit. That would give an interesting power curve that would rise as the rpm increased much like an ICE. Except of course for the fact that full torque would be available at 0 rpm.


You make solid point, I am not really sure, I was just quoting an email I got from Kostov Motors which says such...

What we need is power curves for motors that have 300+V and 1000A controllers applied to them! Just as ICE's power curves are showing peak values, we need the same...patience is not my strong point...


----------



## Batterypoweredtoad (Feb 5, 2008)

Oh I am anxious as well! It is a cool time to be an EV fan!


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## Duncan (Dec 8, 2008)

Hi,
I just did some basic physics, you may be interested in these tables

For a 650 Kg vehicle I calculated best possible accelerations with
100 kw, 200 kw, 400 kw and 800 kw

I have highlighted the 200 yard and 400 yard times

These assume that all of the power goes into the vehicles kinetic energy


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## Qer (May 7, 2008)

Duncan said:


> For a 650 Kg vehicle I calculated best possible accelerations with
> 100 kw, 200 kw, 400 kw and 800 kw


Did you calculate with a constant power over the whole rpm-range? If so you'd need infinite current at 0 RPM...


----------



## Bowser330 (Jun 15, 2008)

Duncan said:


> Hi,
> I just did some basic physics, you may be interested in these tables
> 
> For a 650 Kg vehicle I calculated best possible accelerations with
> ...


800kw will get you 79mph in 0.5 seconds?????


----------



## Duncan (Dec 8, 2008)

Hi Bowser,
800kw for 0.5 sec is 400Kjoules which is equal to 1/2MV2
V2 = 400,000 x 2 / 650kg = 1230
V = 35 m/sec
35 m/s = 126 km/hour = 79 mph

Mind you you need to be pulling 7G to get there, 
Catapult anybody?

I did those tables to give myself a reference point, they represent the absolute maximum that can be done with those powers at that weight independent of gear ratios, grip, voltage or anything


----------



## Qer (May 7, 2008)

Duncan said:


> 800kw for 0.5 sec is 400Kjoules which is equal to 1/2MV2


But at 0 RPM you get 0 kW out, so I'd say the numbers are a little optimistic.


----------



## major (Apr 4, 2008)

Qer said:


> But at 0 RPM you get 0 kW out, so I'd say the numbers are a little optimistic.


What Q is trying to tell you, I think, is that you need to use F = m * a to figure acceleration, not peak power.

major


----------



## Drew (Jul 26, 2009)

Duncan said:


> Hi,
> I just did some basic physics, you may be interested in these tables
> 
> For a 650 Kg vehicle I calculated best possible accelerations with
> ...


Unfortunately its a little more complex than that, because you have a distinct limitation when it comes to the tyre grip. Somewhere between 1-1.3g. At a drag strip its a bit different because there is hot rubber on the ground and grip enhancer, but that only really gets you so far, at the end of the day theres still a traction limitation which overrides the basic specs of the powertrain.

If you're after a realistic definition of 0-100 time or quarter mile then what you need to do is get a CoG height and wheelbase for the car to calculate the weight transfer between axles and the static weight distribution. You can use these to calculate how much load is transferred to (or from) the drive axle, then you multiply that out times the Mu for the tyres and times it by gravity to get the tractive effort which you can put down. If you times the tractive effort by your velocity then you end up with the maximum power you can put down at your current velocity.

Usually this (for road cars) will work out at something like 270kW per ton per hundred kilometers per hour, so a car that can put 500kg over its drive axle will be able to put down something like 135kW at 100km/h.

That being said, more power doesn't necessarily equal more acceleration, as the tractive effort you can generate has to move the whole vehicle, not just the drive axle, so the more mass transfer you can get (or ideally using 4x4) the more acceleration you get. Obviously the lighter the vehicle the more acceleration per unit power as well


----------



## Overlander23 (Jun 15, 2009)

Umm... what about drag? Aerodynamic drag is not insignificant at triple digit speeds... or even over 40 mph. I wonder what a lightweight 750hp Prius with really big rear tires would do?


----------



## caspar21 (Apr 8, 2009)

Overlander23 said:


> Umm... what about drag? Aerodynamic drag is not insignificant at triple digit speeds... or even over 40 mph. I wonder what a lightweight 750hp Prius with really big rear tires would do?


other than look really really embarrassing? probably have a very fast top end due to low weight and low drag.

if i am correct: drag is hp, not torque. so if you compared it to a cube van that weighed the samw with the same power figures then it would do better. but not much due to torque being the more important figure in the 1/4 mile.


----------



## Tesseract (Sep 27, 2008)

caspar21 said:


> ... if i am correct: drag is hp, not torque.


Well, it's both, so you are half correct. 

If all else remains the same (gear ratios, velocity, weight, etc.) but drag is increased, then hp required is increased, yes, but it is specifically because more torque is needed.


----------



## caspar21 (Apr 8, 2009)

is it possible to make a ride that can compete with top fuel dragsters?
or even funnycars?

has anyone looked into the numbers required?

up till now i have only seen bracket racing done with electrics.
i know there is no class made for them yet. but it would be interesting to see if it is possible.


----------



## Juiced (May 2, 2009)

"is it possible to make a ride that can compete with top fuel dragsters?
or even funnycars?"

Not yet.

"has anyone looked into the numbers required?"

Yes, the present technology does not have the energy or delivery systems
to compete with 7000 HP. 

"up till now i have only seen bracket racing done with electrics.
i know there is no class made for them yet. but it would be interesting to see if it is possible."

NHRA does have a class, (we have the Motorcycle versions) but not enough vehicles to fill it anywhere. 

Electrics is still in its infancy, thanks to cheap oil in the 1800's and the lack of funding to progress the technology. At one time whaaaaaaay back when, there were more electric cars than gas. 

Ed


----------



## CroDriver (Jan 8, 2009)

Juiced said:


> Yes, the present technology does not have the energy or delivery systems
> to compete with 7000 HP.
> 
> 
> Ed


Yes, we can't compete with 7000 hp now but I'm sure that 1000 hp is possible. 1000 electric hp would probably beat even 1500 gasoline hp if the batteries wouldn't weight too much (which they won't since A123 is the only option for such a power now) 

I'm already working on something like this


----------



## Bowser330 (Jun 15, 2008)

caspar21 said:


> is it possible to make a ride that can compete with top fuel dragsters?
> or even funnycars?
> 
> has anyone looked into the numbers required?
> ...


http://www.edmunds.com/insideline/do/Features/articleId=120159

So 8000hp and can do 1/4 mile in ~4.5 seconds....

Well.....

The killacycle has two 6.7" DC forklift motors and one Zilla Z2K controller and can do the 1/4 mile in 7.8 seconds...

With a "Top-Fuel" dragster body & frame, two 11" motors (fully built for high amperage and high rpm) or maybe two 13" motors or maybe four motors.... Two (four?) 2000-Amp controllers one for each motor and body full of lithium A123 cells....

I don't see why electrics couldn't compete well....


----------



## Juiced (May 2, 2009)

Bowser330 said:


> http://www.edmunds.com/insideline/do/Features/articleId=120159
> 
> So 8000hp and can do 1/4 mile in ~4.5 seconds....
> 
> ...


Great optimism but...
Nope, not the same, not even close. 

I have been on both sides of this fence and as much as I would love to see it happen, it will not for many years. 

Ed
speeddemonracing.net
juiceddragracing.com


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## CroDriver (Jan 8, 2009)

Bowser330 said:


> I don't see why electrics couldn't compete well....


Weight?


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## Juiced (May 2, 2009)

That is one area.

It take much more HP to go from 7 seconds to 4 seconds due to the HP
to overcome aerodynamic drag and the compression of time. 

To go from 14 second time to 12 seconds in a 1/4 mike pass is not that hard, maybe a hundred HP. To go from 7 seconds to 4? Thousands....

Ed


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## Drew (Jul 26, 2009)

http://www.evo-electric.com/products/electric-motors-and-generators-hybrid/

The above are easily the highest power density motors I've found, stacking a few sets of these would mean you'd easily be able to knock out a thousand kilowatts or more.

I'd also suggest that at that sort of power output I'd have thought that using capacitors would be a much better idea than batteries, you don't need a long range but you do need a very high power output for a short period of time.


----------



## JRP3 (Mar 7, 2008)

Drew said:


> http://www.evo-electric.com/products/electric-motors-and-generators-hybrid/
> 
> The above are easily the highest power density motors I've found, stacking a few sets of these would mean you'd easily be able to knock out a thousand kilowatts or more.


Each section has a max rating of 145kw at 88lbs. To get 1000kw you'd need 7 segments at 616lbs, and you're still no where near the power levels needed to compete with 6000+hp.


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## DavidDymaxion (Dec 1, 2008)

This is really simple, too simple, but sees if electrics are even in the ball park.

The killacycle makes 500 hp and weighs 653 lbs. The batteries are about 1/4 of the weight.

14 Killacycles would be 7000 hp and 9000 lbs. That's about 4x the weight of an all out dragster. Even if you had batteries that weighed zero, 14 Killacycles would still weigh ~7000 lbs.


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## Bowser330 (Jun 15, 2008)

DavidDymaxion said:


> This is really simple, too simple, but sees if electrics are even in the ball park.
> 
> The killacycle makes 500 hp and weighs 653 lbs. The batteries are about 1/4 of the weight.
> 
> 14 Killacycles would be 7000 hp and 9000 lbs. That's about 4x the weight of an all out dragster. Even if you had batteries that weighed zero, 14 Killacycles would still weigh ~7000 lbs.


..each cell weighs 70grams..and is 2.3AH & 50C capable = 115A

Im thinking purpose-built lightweight aerodynamic dragster with four 11" motors (800lbs) with 2000A into each...needs 8000A capable burst pack.. parallel configured...

8000/115 =~ 70, 70*100 (100 cells in series to make 330V) = 7000cells

7000 cells * 70g = 490kgs =~ 1000lbs

Drew mentioned ultracaps, maybe they could be integrated to make a better lithium-hybrid-pack or used as complete substitute to the lithiums...

It would still be cool to see how close they could get to 4.5 seconds mark even if they don't reach it...im not usually an optimist in life but with all the adversity electric technology has had...it needs all the good karma and support it can get...

Maybe CalMotors Heavy-Duty AC systems would do the trick??
http://www.calmotors.com/products.php?category=products&page=heavy

How about one of those for each wheel..hmm..


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## JRP3 (Mar 7, 2008)

Bowser330 said:


> Maybe CalMotors Heavy-Duty AC systems would do the trick??
> http://www.calmotors.com/products.php?category=products&page=heavy
> 
> How about one of those for each wheel..hmm..


At 538 lbs each combined for motor and controller you're talking about 2152lbs and still not even 2000 hp.


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## JRP3 (Mar 7, 2008)

DavidDymaxion said:


> 14 Killacycles would be 7000 hp and 9000 lbs.


Since you wouldn't need 24 wheels, among other things, there should be some weight savings available


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## DavidDymaxion (Dec 1, 2008)

Heh heh, good point! On the other hand, the dragster will need to be built heavier because it is longer and has to handle torsional twist. It still is mighty impressive an electric can be within around a factor of 4, though!


JRP3 said:


> Since you wouldn't need 24 wheels, among other things, there should be some weight savings available


----------



## Bowser330 (Jun 15, 2008)

JRP3 said:


> At 538 lbs each combined for motor and controller you're talking about 2152lbs and still not even 2000 hp.


ok ok forget the AC part...


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## Drew (Jul 26, 2009)

Why would you want to go immediately for a 5 second pass?

I'd say that aiming a little lower would be a good start...

So say you had 6 of those guys you'd be able to sustain 870kW for 60 seconds and it would weigh in at about 240kg, assuming you could get yourself down the drag strip in say, less than 10 seconds you'd need 8.7MJ of energy to power the whole run... 

Assuming you were running a nominal 800V then 14 Farads would be enough to get you down the run, but to maintain an acceptable voltage then you'd be after maybe 4 times that, so that the energy loss would give you an end run voltage of something more like 600V...

I appologise if my calculations regarding the capacitors are incorrect, I'm just starting to get into the electronics side of things.


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## caspar21 (Apr 8, 2009)

what does 14 farads weight these days?


----------



## major (Apr 4, 2008)

caspar21 said:


> what does 14 farads weight these days?


Hi caspar,

Farads don't weigh anything  I'm holding a 2600 farad cap right now. 525 grams. That puts it at 202 mg/F. So 14 F would be 2.83 grams. What you need to look at is energy, or specific energy. The Maxwell 165 F, 48.6 V module has a specification of Emax = 3.81 Wh/kg. Also, Pd = 3,200 W/kg and Pmax = 7,900 W/kg. So once you have your required energy and power, you can figure the mass of capacitor needed.

WRT running the 1/4 mile on ultracaps, look up the BYU EV-1. They did some respectful runs on caps only. And I think they published some papers detailing the energy profile.

Regards,

major


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## 2cycle (Jul 2, 2009)

I just read the story on the BYU ultracap powered car. Why wouldn't ultracaps be the answer for drag bikes like Killacycle instead of batteries? If they are lighter and they only need to power it for 9 seconds that would be perfect. What are the limitations with ultracaps?


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## major (Apr 4, 2008)

2cycle said:


> I just read the story on the BYU ultracap powered car. Why wouldn't ultracaps be the answer for drag bikes like Killacycle instead of batteries? If they are lighter and they only need to power it for 9 seconds that would be perfect. What are the limitations with ultracaps?


Bill, the owner of Killacycle, doesn't like them  There's more to it. Maybe I can expand later, or somebody else is welcome to jump in 

major


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## Bowser330 (Jun 15, 2008)

major said:


> Bill, the owner of Killacycle, doesn't like them  There's more to it. Maybe I can expand later, or somebody else is welcome to jump in
> 
> major


Please do expand...

What are the reasons behind him not liking them?


----------



## major (Apr 4, 2008)

Bowser330 said:


> Please do expand...
> 
> What are the reasons behind him not liking them?


Kinda busy right now.  Bill and I had it out about this on the EVDL a year or two ago. Can you search those achieves?


----------



## major (Apr 4, 2008)

major said:


> Kinda busy right now.  Bill and I had it out about this on the EVDL a year or two ago. Can you search those achieves?


 
Here's what Bill had to say:



> Look in the archives. I proved quite conclusively that Ultra caps are
> unsuitable for drag racing.
> 
> There are two issues that folks don't take into account. One is that
> ...


Not that I agree with him 

Regards,

major


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## DavidDymaxion (Dec 1, 2008)

Major -- do you work for or with Maxwell? Can you share any insider insights for us? Enquiring minds want to know. 

It's very fair that you post Bill's disagreement with you. I'm curious how you differ. I looked at some Maxwell specs http://www.maxwell.com/ultracapacitors/datasheets/DATASHEET_48V_series_1009365.pdf and don't see how they'd beat A123 batteries in a drag race. Bill is pulling close to 4 kW/kg out of the A123 batteries, but the Maxwell specs say they can only pull 3 kW/kg DC. Does Maxwell have some more powerful prototype capacitors? 


major said:


> Here's what Bill had to say:
> 
> Not that I agree with him
> 
> ...


----------



## major (Apr 4, 2008)

DavidDymaxion said:


> Major -- do you work for or with Maxwell? Can you share any insider insights for us? Enquiring minds want to know.


David,

You and your inquiring mind can rest assured that I do not work for nor am compensated by Maxwell Technologies or any other UC company. And I am not an insider in anything. But have some experience with a number of differnet UC products, as well as batteries of different sorts. But as always, anything I say here should be considered opinion and the reader can choose to take it for what it is worth, or check it out further.



> It's very fair that you post Bill's disagreement with you. I'm curious how you differ. I looked at some Maxwell specs http://www.maxwell.com/ultracapacitors/datasheets/DATASHEET_48V_series_1009365.pdf and don't see how they'd beat A123 batteries in a drag race. Bill is pulling close to 4 kW/kg out of the A123 batteries, but the Maxwell specs say they can only pull 3 kW/kg DC.


The way I read the spec is 7,900 W/kg for the large module. 

Bill claims Killacycle needs 500 Whr to do the 1/4 mile, right? But how big is his battery? And Bill uses manufacturer's specifications to compare the UC to his battery. Does he use his motors within the nameplate rating? Those specs you see from Maxwell are for a product validated to a million cycles. You think Bill is going to do a million passes on the Killacycle? Why not press the limits on the UC? Get it down to a dozen cycle life. Then maybe there would be good fight 

And I have told Bill straight out that I think he has the best energy storage system for his application. But I gotta think UCs might challenge that.



> Does Maxwell have some more powerful prototype capacitors?


I'd be surprised if they didn't have something in the lab. But I know nothing of it.

Regards,

major


----------



## icec0o1 (Sep 3, 2009)

What do you guys think about Lipo batteries like this one:
http://www.hobbycity.com/hobbycity/...Name=Polyquest_XF_3700mAh_4S_45C_-_90C_Lipoly_

At 90C burst discharge rate, you'd only need 120 of these batteries to max out a Zilla 2k controller (at 600Kw) which would only weigh 50kg or 110lb.

At the chance of burning up down the track, could a 6-8 seconds dragster be made out of these?

A lot of people say that battery technology isn't good enough for now but I think the good battery technologies just haven't become mainstream yet?


I did some more math. A lipo battery from the above technology delivering 6 Megawatts would weigh 510kg or 1123 lb (ignoring additional wire to combine individual packs, all 682 of them @ $324 = $221,000). With a lightweight frame, what kind of times do you think this dragster would get? I'm assuming this is comparable to 7000-8000HP.


----------



## JRP3 (Mar 7, 2008)

Interesting that Enerland is part of A123 yet I've never seen 90C rates listed for A123 cells. http://www.enerland.com/


----------



## caspar21 (Apr 8, 2009)

JRP3 said:


> Interesting that Enerland is part of A123 yet I've never seen 90C rates listed for A123 cells. http://www.enerland.com/


looks like the "XF" series of cells are not yet listed on enerland.com yet.
possibly behind in their updates?


----------



## DavidDymaxion (Dec 1, 2008)

http://www.maxwell.com/ultracapacitors/datasheets/DATASHEET_48V_series_1009365.pdf

You have to dig down into the fine print of the specs, near the end they list the equations for Pd and Pmax. Pmax ~ 8 kW/kg is for AC operation (1 kHz, and it doesn't spec the duty cycle). Pd ~ 3 kW/kg is for DC operation. Of course, EVs draw DC power from the batteries/capacitors, so Pd is the more important number (more on this later).

The Pmax equation is the theoretical max power (V/2)^2/R (sagged to 1/2 Voltage), but the Pd equation is about 1/2 the theoretical max power. My guess is the Pmax AC case is running about 50% duty cycle, and they have to run 1/2 power when running DC -- maybe something gets too hot or burns if you run it at full theoretically possible power.

So could a NEDRA racer push beyond the "safe" 3 kW/kg DC number for just a few seconds? Maybe if the capacitor were cooled first? Maybe so, it would be interesting to see.

Let's say the full max theoretical AC 8 kW/kg is possible at DC (2.7 times spec). Let's say it can continuously deliver 8 kW (it can't). There is < 2 seconds of power. So let's drop to A123 rates, 4 kW/kg. Now there is 4 seconds of power. For the Killacycle to cover the 1/4 mile it needs about 8 seconds of power, so now the Maxwell caps are down to 2 kW/kg, half of A123 batteries.

There is still hope, maybe the capacitors can be overvolted. Double the voltage on them, get 4x the energy, and then they might be A123 beaters if the heat can be tolerated. Does anyone have experience that way, can they tolerate overvoltage?

I definitely think there's hope for capacitors, another factor of 4 or so would make them better than A123 batteries for a drag race.



major said:


> ...
> The way I read the spec is 7,900 W/kg for the large module.
> 
> Bill claims Killacycle needs 500 Whr to do the 1/4 mile, right? But how big is his battery? And Bill uses manufacturer's specifications to compare the UC to his battery. Does he use his motors within the nameplate rating? Those specs you see from Maxwell are for a product validated to a million cycles. You think Bill is going to do a million passes on the Killacycle? Why not press the limits on the UC? Get it down to a dozen cycle life. Then maybe there would be good fight
> ...


----------



## Bowser330 (Jun 15, 2008)

icec0o1 said:


> What do you guys think about Lipo batteries like this one:
> http://www.hobbycity.com/hobbycity/...Name=Polyquest_XF_3700mAh_4S_45C_-_90C_Lipoly_
> 
> At 90C burst discharge rate, you'd only need 120 of these batteries to max out a Zilla 2k controller (at 600Kw) which would only weigh 50kg or 110lb.
> ...


No one said that top fuel was a cheap sport to compete in....I am pretty sure with a sponsorship you could cut the cost of the lipos significantly as well.

IIRC Lipos don't have good charging profiles which would make them difficult to charge between runs..but their output profiles are very nice...


----------



## caspar21 (Apr 8, 2009)

Bowser330 said:


> IIRC Lipos don't have good charging profiles which would make them difficult to charge between runs..but their output profiles are very nice...


there is also the problem of going back to explosively volatile power sources. you know someone will try to legislate it out(probably after you start winning).


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## caspar21 (Apr 8, 2009)

Bowser330 said:


> IIRC Lipos don't have good charging profiles which would make them difficult to charge between runs..but their output profiles are very nice...



heyy.. wait a minute.. they are designed for 1C charge rates.

100 Ahr, charges at 100 amps. (aprox 1.1hr for full charge)
40c discharge is 4000 amps.
sag is much less than lead based technology.

that should be enough for half the power system on a dragster.


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## Bowser330 (Jun 15, 2008)

caspar21 said:


> heyy.. wait a minute.. they are designed for 1C charge rates.
> 
> 100 Ahr, charges at 100 amps. (aprox 1.1hr for full charge)
> 40c discharge is 4000 amps.
> ...


I guess you're right. I stand corrected...


----------



## lonestarrpm (Aug 18, 2011)

Late to the show, but is PWM DC? or is it frequency based aka AC?

I'm struggling with wanting occasional 1000+ amp draw at 170v
but not needing a pack that supports that amount of amps
for a long duration.

I'm considering a Porsche Boxster as a commuter and occasional track
vehicle for 20-25min stints.

Would love something that could deliver the 8-10C on occasion
but normally run 1C

Mike



DavidDymaxion said:


> http://www.maxwell.com/ultracapacitors/datasheets/DATASHEET_48V_series_1009365.pdf
> 
> You have to dig down into the fine print of the specs, near the end they list the equations for Pd and Pmax. Pmax ~ 8 kW/kg is for AC operation (1 kHz, and it doesn't spec the duty cycle). Pd ~ 3 kW/kg is for DC operation. Of course, EVs draw DC power from the batteries/capacitors, so Pd is the more important number (more on this later).
> 
> ...


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## Tesseract (Sep 27, 2008)

lonestarrpm said:


> Late to the show, but is PWM DC? or is it frequency based aka AC?


Good question with no exact answer.... Most of the current will be DC, but some proportion will be triangular AC ripple. How much is AC depends on a lot of different variables including the ESR and ESL of the battery pack and wiring (running the + and - cables next to each other helps here), the duty cycle of the PWM waveform (max ripple occurs at 50% duty, no ripple at 0% and 100% duty), and, finally, the amount of capacitance inside the controller and its ESR/ESL.

When all is said and done, however, the AC ripple component will typically be less than 20% of the total current (e.g. - if you are drawing 1000A from the pack the actual current will vary on a cycle by cycle basis between 900A and 1100A, for an average current of 1000A with 200App of ripple).



lonestarrpm said:


> I'm struggling with wanting occasional 1000+ amp draw at 170v but not needing a pack that supports that amount of amps for a long duration.


Note that peak current draw from the pack is a very elusive thing: it only occurs at the brief moment in time when the controller first hits 100% duty cycle which corresponds to a particular RPM and torque load for the motor. After that point the duty cycle remains pegged at 100% but if RPM continues to climb then motor and battery current will tail off inversely proportional to RPM. 

And given that, I'd aim for a little more voltage even at the expense of less duration at 1000A (or even less than 1000A max).



lonestarrpm said:


> Would love something that could deliver the 8-10C on occasion but normally run 1C


You can easily do that with Headway cells or by doubling up on 100Ah prismatic cells, tripling up on 60Ah prismatics, etc...

A Porsche Boxster should make for a seriously fun EV...


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## lonestarrpm (Aug 18, 2011)

So All the switching frequencies (8 or 15k) are internal and
the output looks like a DC with ripple, and the extent of the 
ripple is due to the duty cycle.

Totally get it now. 

The output is not chopped/pulsed -- but internally it is and banks 
of caps, etc are attempting to smooth out the pulse into a DCish waveform at the voltage you are after.

That and putting a huge cap on the output wouldn't be the smart thing to do as you'd have no throttle control. 

Sorry wasn't thinking it through properly.

If you could use the ultra caps internal to a controller design -- then you might be able to see an AC waveform.

thanks,

Mike




Tesseract said:


> Good question with no exact answer.... Most of the current will be DC, but some proportion will be triangular AC ripple. How much is AC depends on a lot of different variables including the ESR and ESL of the battery pack and wiring (running the + and - cables next to each other helps here), the duty cycle of the PWM waveform (max ripple occurs at 50% duty, no ripple at 0% and 100% duty), and, finally, the amount of capacitance inside the controller and its ESR/ESL.
> 
> When all is said and done, however, the AC ripple component will typically be less than 20% of the total current (e.g. - if you are drawing 1000A from the pack the actual current will vary on a cycle by cycle basis between 900A and 1100A, for an average current of 1000A with 200App of ripple).
> 
> ...


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