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Thread: Electric 818 | AC & LiFePO4 configuration

  1. #41
    Research Calibrator sponaugle's Avatar
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    Quote Originally Posted by Oppenheimer View Post
    ...which the graph does not appear to show. There is no 'advantage' off the line shown here that we would expect from the torquey EV. Of course, this is for starting at 10 MPH, not off-the-line, but still. It seems 'off' to see such 'linear' speed curve comparisons when one vehicle is all torque, the other high HP.
    It is critical to understand this is not an EV vs Gas Engine comparison. This is a very low power EV engine compared to a high HP gas engine. The STI engine in this case makes more torque at 2500 rpm then the EV does ever. It is true the EV makes more torque at 500 rpm then the STI at 500rpm, but the gearing the subaru transmission does not take advantage of that.

    There are some obvious advantages even this underpowered EV car would have. In a real like situation the if both cars were cruising along at 10mph and punched it, the EV car would pull ahead almost instantly. In this case that instant would last about a second then the STI would trounce it. This is an unfair comparison of a 350hp engine vs a 75hp one. It is amazing the 75hp one is even in the running.

    In a real zero speed launch however, the STI would have an advantage. When I use launch control to launch my car, my RPMs never drop below 3000 rpm. I effectively have an engine that produces 200+ lb-ft of torque at zero mph. There is of course loss in the clutch slipping (which is critical to the lack of link between engine rpm and speed), however in all cases the limiting factor is traction. The EV car would instantly break the rear tires loose, and the 4WD STI would have a tractive advantage.

    Quote Originally Posted by Xusia View Post
    That's really enlightening. There is one thing that's making me scratch my head, and I'm not sure if it's just the EV system described here or something else. I've seen EVs literally leave in the dust cars with engines that make significantly more HP than the STi described here (and weight about the same). This was mostly at speeds less than 100 mph, and because of the RPM limitations of motors, I assume said car would eventually catch up. The point is, there was no denying the acceleration advantage provided by the torque of the motor vs. a more powerful engine.
    The head scratching part is a combination of a few things.. First I suspect in many cases the EV car was lighter. In a drag car case you only need enough batter for a run... while the gas car carries the full weight of the engine and empty tank.

    Second, this is not a high output EV motor. Consider the Tesla NON-S motor is 362hp, and the S is 416hp. Those are high output EV motors, and indeed they could potentially trounce an equal or more gas engine.

    The thing to get across is in the phrase 'the torque of the motor'. This EV motor does not have much torque. The one in the Tesla does.

    I do believe the long term future of performance cars lies in the electric motor. One drive in a Tesla S can confer that quickly.

    Also, I'll make some graphs using a stock WRX engine for comparison... that will be more instructive..


    Jeff
    Last edited by sponaugle; 05-07-2013 at 04:08 PM. Reason: Corrected Tesla power output from post below.

  2. #42
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    Great post Jeff. How are the shift points being determined?

  3. #43
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    Here are the Tesla Model S power options from the Wikipedia article.

    Tesla-Model-S-powerplants.gif

  4. #44
    Research Calibrator sponaugle's Avatar
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    Quote Originally Posted by Evan78 View Post
    Great post Jeff. How are the shift points being determined?
    I shifted when torque at the wheels was greater in the next gear, which is the most ideal shift point in terms of power delivery. It is very evident that the gearing of the WRX box is not ideal for this, because you spend so little time in the highest torque areas.. A longer gear box would be better, especially if I factor in shift time. I'll add a delay for each shift point to make it a bit more accurate.

    Also this is using a WRX CD and frontal area, so the speed info above 100mph is suspect for the 818.

    Now is you had two of these motors, we would be talking.

  5. #45
    Senior Member Xusia's Avatar
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    I'm pretty sure weight had nothing to do with it. In fact, I believe most of the EVs were a bit heavier with a motor and batteries than with their original gas engine. They were daily drivers, not purpose built drag cars.

    I think the issue is the relatively low torque output of the motor being discussed here. The motors I've seen that out accelerate engines with more HP have a lot more torque. I think you hit it when you pointed out how much torque the STi engine puts out. I also think in this specific case, the transmission may not be helping acceleration.

  6. #46
    Research Calibrator sponaugle's Avatar
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    Quote Originally Posted by Xusia View Post
    I'm pretty sure weight had nothing to do with it. In fact, I believe most of the EVs were a bit heavier with a motor and batteries than with their original gas engine. They were daily drivers, not purpose built drag cars.

    I think the issue is the relatively low torque output of the motor being discussed here. The motors I've seen that out accelerate engines with more HP have a lot more torque. I think you hit it when you pointed out how much torque the STi engine puts out. I also think in this specific case, the transmission may not be helping acceleration.
    Yep, with the right motor those cars can fly. If you look at the new Tesla Model X (with two motors from the current tesla), it is looking like 0-60 will be 4.0 in the S version.. in an SUV that weighs 4500lbs. That is what 800+ EV HP gets you.

    So has anyone considered trying to fit two of these motors instead of just one?

    Jeff

  7. #47
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    Any chance of getting a copy of your spreadsheet?

  8. #48
    Senior Member bromikl's Avatar
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    Quote Originally Posted by sponaugle View Post
    It is critical to understand this is not an EV vs Gas Engine comparison. This is a very low power EV engine compared to a high HP gas engine. Jeff
    Diesel engines have a lot more torque than gas, but no one would assume a VW TDI is going to lap an LS7.

    MODERATOR: Cleaned up.
    Last edited by ehansen007; 05-09-2013 at 06:28 PM.

  9. #49
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    Quote Originally Posted by bromikl View Post
    Diesel engines have a lot more torque than gas, but no one would assume a VW TDI is going to lap an LS7.
    Is this sarcasm? I feel like Sheldon Cooper
    Last edited by ehansen007; 05-09-2013 at 06:29 PM.

  10. #50
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    Quote Originally Posted by Evan78 View Post
    Is this sarcasm? I feel like Sheldon Cooper
    ^ haha I wish there was a like button on the forums.

  11. #51
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    Personally I think it would be a shame to have such a low HP electric 818. I think you would get a lot better results with the siemens transaxle, or even better a 9 inch Netgain Motor with a 100 cell pack of the 60AH CALB CA cells with a Soliton 1.

    Right now the motor options are not great for the homebuilder who wants a high HP and lightweight setup. The Azure Dynamics Siemens AC motor is setup with lower voltage than their usual, which lowers RPM and HP, and the controller is oversized physically, but undersized electrically. Netgain Motors DC are good, but a bit of a black art on running them high HP and they are definitely heavy, no regenerative braking, and you have to deal with the brushes.

    The CA series will actually pull 15C, so you could get 900 amps out of them for brief periods. The Warp 9 from Netgain with the new helwig brushes can handle 200 volts, 900 A x 200 V = 180 kilowatts, let's take out 30% for inefficiencies, you get 126 KW, x 1.34 to convert to HP, about 164 HP, not bad. EVTV dynoed a soliton 1 and a Warp 9 with a 192 Volt pack at 157 HP at the wheels. i would go with the full 330 volt pack to have less voltage sag.

    You could go with the Warp 11HV (63 pounds heavier), which is a nine inch motor with interpoles which can handle 288 Volts, so then 243 HP using the same calculations as above.

    My proposed Electric 818:

    100 60 AH Calb CA Cells (450 pounds)
    Netgain WarpDrive 11HV Motor (223 pounds)
    Evnetics Soliton 1 Controller (33 pounds)
    Horsepower = 243
    Storage Capacity = 19.2 KWH
    Noise: Very Little
    Range: About 70+ Miles
    0-60 A tick quicker than the WRX ICE Version

    Cheers,

    Nucleus

  12. #52
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    Nucleus - What would the cost be on that setup? What gearbox would work well?

  13. #53
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    Cost Estimate Electric FFR 818 with Soliton 1 Netgain WarP 11HV 330V CALB CA LiPO4

    Quote Originally Posted by Evan78 View Post
    Nucleus - What would the cost be on that setup? What gearbox would work well?
    I would use the stock gearbox for this setup.

    Rough cost breakout:

    100 60 AH Calb CA Cells $9000
    Netgain WarpDrive 11HV Motor $3000
    Evnetics Soliton 1 Controller $3000
    Motor Adaptor $1200
    Various Bits $2000
    Charger $2000

    Total $20,200

    After reconsidering, I don't think this setup would be faster than the ICE, too much weight increase. But it would comparable at least in acceleration.

    The downside to the "inexpensive" DC setup that I see is that when you lift off the throttle you just coast. But until the AC motor and controller options improve, this is the best way to get good power.

    You could switch to the 100 AH cells and get a bigger controller like a Zilla or two Solitons and you could get 400 HP from the same motor... But the battery pack would weigh 750 pounds!

    The Lithium Polymer (LiPo) batteries have amazing discharge rates (35C!), so you can have a much smaller and lighter pack, but they are much more expensive and may require cooling and BMS, I don't know that much about them.

  14. #54
    Senior Member Xusia's Avatar
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    Is there a battery pack (or smaller batteries that could be arranged in a way) that delivers high voltages (192+) and high current, but has low capacity (i.e. it doesn't last long)? I ask because I'd prefer to get range by adding an on-board generator, rather than batteries.

  15. #55
    Senior Member RM1SepEx's Avatar
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    batteries can be connected in series or parallel to get any voltage or amperage capacity... nominal LiFePO4 voltage is 3.2 volts. so for example if you want 192 volts with 40 amp hrs you just series connect 192v/3.2v = 60 batteries 7.68KWH capacity you could also connect these cells for 96 volts and 80 amp hrs 7.68 KWH capacity. they make these batteries in a variety of capacities and form factors

  16. #56
    Senior Member Xusia's Avatar
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    That's not completely true. Perhaps it's better to say that's only true so long as you don't care how many batteries you wind up with in the pack or how much they weigh. Or if you don't care about the amperage. But I do care, and the batteries discussed in this thread can't produce the voltage at high current rates without also having a large amp-hour rating and weighing a lot.

    So what I'm asking is if there are batteries that can produce the same 3.2 volts at a high current rate, but are much smaller (and therefore have much less capacity)? Ideally I'm looking for a battery pack that can power the car like the blazes - but for minutes, not hours.

  17. #57
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    Quote Originally Posted by Xusia View Post
    Is there a battery pack (or smaller batteries that could be arranged in a way) that delivers high voltages (192+) and high current, but has low capacity (i.e. it doesn't last long)? I ask because I'd prefer to get range by adding an on-board generator, rather than batteries.
    What type of current are you looking at?

  18. #58
    Senior Member RM1SepEx's Avatar
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    Quote Originally Posted by Xusia View Post
    That's not completely true. Perhaps it's better to say that's only true so long as you don't care how many batteries you wind up with in the pack or how much they weigh. Or if you don't care about the amperage. But I do care, and the batteries discussed in this thread can't produce the voltage at high current rates without also having a large amp-hour rating and weighing a lot.

    So what I'm asking is if there are batteries that can produce the same 3.2 volts at a high current rate, but are much smaller (and therefore have much less capacity)? Ideally I'm looking for a battery pack that can power the car like the blazes - but for minutes, not hours.
    check out RC batteries... there are several high current output types. see some of the drag racing sites for addl info. Headway cells for example... LiFePO4s are not high output current types... typical 3X cont discharge rated. lead/acid in excess of 10X to get current capability high enough you need a pretty big/heavy LiFePO4 pack.

    You want to look at ampzilla controllers etc too

  19. #59
    Senior Member Oppenheimer's Avatar
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    Quote Originally Posted by Xusia View Post
    Is there a battery pack (or smaller batteries that could be arranged in a way) that delivers high voltages (192+) and high current, but has low capacity (i.e. it doesn't last long)? I ask because I'd prefer to get range by adding an on-board generator, rather than batteries.
    I think you could accomplish what you are looking for with capacitors. You can quickly charge them, and quickly discharge them. They are light, they can be arranged in any config that helps you balance space & weight, don't have to worry about how many times you charging cycles you give them, etc.

    One config I'd like to see is two on board generators, a small one that was just enough to cruise at like 75 MPH, and a larger one that gave you all the power you could want, with capacitors to cover the gap. Both setup to power the electric drive motors directly, both setup to run most efficiently at a set rpm. Maybe using direct injection stratified charge, etc. At highway cruise you are running off the smaller generator, which also keeps the capacitors fully charged. When you call for more go, the capacitors supply the juice, and if you call for more go for more than a few seconds, the second generator comes online.

    The goal is balance excellent highway mileage with the capability for very extreme acceleration when desired. While its true you are hauling around a generator you aren't using for much of the time, you aren't hauling around heavy batteries. This would not get good city mileage at all of course, as you would be running the larger generator most of the time.

    Electric drivetrains are the future. Will that be powered by battery, or ICE generator, or Fuel Cell, or Mister Fusion, or some combination, I don't know. But we can start perfecting the performance if what comes downstream of the power source now (the motors, the suspension, etc), even while we wait for the power source stuff to work itself out.

  20. #60
    Senior Member Xusia's Avatar
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    I agree about electric drive trains being the future. There are just too many advantages to ignore.

    In regards to capacitors, I have thought about that, but ruled them out for 2 reasons:
    1. I think appropriately sized capacitors would cost more than batteries.
    2. Capacitors don't maintain their charge as well over time and would therefore most likely require running the engine before any movement can occur.

    As far 2 generators, I can understand the logic, but think there is probably a more weight efficient way to deal to accomplish the goal. One idea would just be to have a generator run at 2 speeds: Low RPM for cruising; High RPM for when you need extra power. High RPM would probably not be as efficient, but how often would you REALLY need that much power?

    Another idea would be a trick current hybrids use: Start/stop. Run the high power generator for short bursts, and rely on the capacitors/batteries in between.

    Last idea is to rely on the law of averages. Use a mid-sized generator, and simply size the capacitors/batteries to accommodate the maximum amount of time you think you'd need full power.

    I have a hard imagining daily driver cars really needing full power for extended periods of time. But if they do, I'd say just ditch the smaller generator all together and use only the larger one. The logic being if you really need full power that much of the time, you don't really have a good use for the smaller generator.

  21. #61
    Senior Member RM1SepEx's Avatar
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    2 generators, two speeds, voltage of pack determine generator rpm... too much complexity/weight
    serial hybrid design makes sense
    size motor for good acceleration/performance
    size generator to replenish nominal cruising current/voltage
    motor speed is dependent on voltage variation, pack needs to be charged at a voltage above nominal pack voltage
    size battery for some nominal desired range... typical thought is 40-50 miles
    most vehicles can "cruise" with 15-18 HP at 65 mph
    you need to generate +15% more than that due to conversion losses... BEST case
    weight is the enemy as is aero drag
    it all comes down to energy storage density.
    as an alternative you could do small FWD diesel for long range drive and use electric RWD plug in. Use both for best acceleration, easy to do it this way with 818, the front hubs support drive axles and CV joints

    See XR3 RQ Riley

    http://www.youtube.com/watch?v=hLASs0ueF7I

  22. #62
    Senior Member Xusia's Avatar
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    If all you are interested in is fuel economy, that approach makes sense. If you want an electric vehicle for other reasons, then that's not necessarily the best approach (that's not to say it's not a viable option, just that other approaches could make more sense).
    Last edited by Xusia; 05-13-2013 at 11:54 PM.

  23. #63
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    Lightbulb A High Power Lower Capacity Battery Pack with Turnigy Cells

    Quote Originally Posted by Xusia View Post
    That's not completely true. Perhaps it's better to say that's only true so long as you don't care how many batteries you wind up with in the pack or how much they weigh. Or if you don't care about the amperage. But I do care, and the batteries discussed in this thread can't produce the voltage at high current rates without also having a large amp-hour rating and weighing a lot.

    So what I'm asking is if there are batteries that can produce the same 3.2 volts at a high current rate, but are much smaller (and therefore have much less capacity)? Ideally I'm looking for a battery pack that can power the car like the blazes - but for minutes, not hours.
    Here is an example pack for what you want, lots of power, light weight, 192 Volts:

    You get 520 of these:18594.jpg

    From here:
    http://www.hobbyking.com/hobbyking/s...gle_Cell_.html

    You wire them in a 52S10P arrangement. That means 52 in Series, 11 in Parallel. Basically 10 serially wired strings of 52, wired in parallel. The 52 in series get you to 192 Volts nominal (LiPoly Batteries are 3.7 Volts). The 10 Parallel take your 35C level to 2030 Amps (5.8 Ah x 35 x 10 = 2030).

    These batteries do 25C continuous 192 x 2030 = 390 KiloWatts = 522 HP theoretical HP in 10 second bursts. Take out 30% for inefficiencies and you get 365 HP.

    Not bad for a 165 pound, 11.1 KWh battery pack.

    Nucleus

  24. #64
    Senior Member Xusia's Avatar
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    I think for my purposes, I'd prob be more inclined to do 5 sets of 52 rather than 10.

    That said, I'm not ready to spill the beans just yet, but this weekend's events mean it unlikely I'll be going EV.

  25. #65
    Senior Member bromikl's Avatar
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    How difficult would it be to place an electric drive motor or two in the front? For extra power when you want it. You could use smaller motors which cost less than one large motor. Maybe it wouldn't be worth the weight, cost or complexity. But could it be done?

  26. #66
    Senior Member RM1SepEx's Avatar
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    anything can be done...
    check for hub motors or use the existing hubs and use the FWD capability that is inherant in the donor parts... don't forget a diff tho
    those batteries will generate tons of heat if you discharge them at high rates... be careful
    the pack described by nucleus should be good for 30 miles or so and will cost $7000

  27. #67
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    So I was watching EVTV and HPEVS is now in production with their siamesed AC-35 motor, basically two motors end to end in one case, only 21 inches long and 150 pounds.

    This motor should put out about 180HP and 200 ft-lbs, so I think it could make a nice 818, it comes with dual Curtiss 500 Amp 144 Volt controllers for $9500. 50 CALB CA 100 Ah cells, and an adapter plate, and you are good to go.

    I like the idea of a lighter weight Electric 818. This would be a 375 pound battery pack and 150 pound motor. Probably 545 pounds total.

    Losing the ICE components like engine, exhaust system, turbo, radiator may save, what? 340 pounds?

    A 200 pound weight gain isn't too bad in the electric car world.

    I like the regenerative action of the AC motor too.

    Nuke

  28. #68
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    In case you are thinking your options are limited to low numbers lets have a look at some of the bigger controllers out there.

    1. Tritium WaveSculptor 200 - AC. 175 KW. I'm not across all the AC offerings, but I believe this is the biggest AC controller that a DIYer can install. http://tritium.com.au/products/waves...otor-inverter/

    2. Soliton 1. DC. The go to controller for DC performance street cars. Rated at 300 KW but with electron shuffling can make 310 KW in theory. http://www.evnetics.com/evnetics-products/soliton-1/

    3. Netgain Warpdrive 360V 1400 Amp version. DC. I don't believe the nameplate numbers, haven't seen many dynos, and not at full voltage, have seen a lower voltage version push 1300 amps. Lets call it good for 468 KW. I'm following a factory five cobra build with this controller. He has it running but not at full power yet. http://www.youtube.com/user/ev99saturn?feature=watch

    4. Zilla 2K EHV. DC. The controller used by drag racers for many years. Any EV drag car you've seen in a video uses this controller. You cannot push 2000 amps out at full voltage it derates down to 1600-1700 amp. Only good for short runs at full power. 600 KW. http://www.manzanitamicro.com/produc...category_id=33

    5. Soliton Shiva (The Destroyer). DC. As used by EVWest in previous years Pikes Peak in a BMW E36 M3. 425V 3000 amps and it can do all of it. Made from 9 150 KW controllers. 1275 KW. Comes with manufacturer guarantee to break something. http://www.evnetics.com/evnetics-pro...soliton-shiva/

    Pick your poison.

  29. #69
    Administrator David Hodgkins's Avatar
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    bump for the last post, which got held up in moderation...


    FFR 5369 Pin Drive, IRS, Trigos, Torsen, Wilwoods, FMS BOSS 302 "B" cam , Mass-flo. CA SB100 (SPCN) Registered
    Delivered 4/23/06. "Finished" 4/2012 (still not done!)


  30. #70
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    Quote Originally Posted by drgrieve View Post
    Comes with manufacturer guarantee to break something.
    I just laughed loud enough to startle coworkers.
    A well stocked beverage fridge is the key to any successful project.

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