Lightning Strike

Discussion in 'Electric Motorcycles' started by voltsxamps, Jan 24, 2019.

  1. ctromley

    ctromley Been here awhile

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    Well, the ride report was based on an early prototype, with lots of questions still to be answered. A few things were cleared up a bit:

    1. Two factories, China and Silicon Valley (which seems to make no sense - labor cost must run high in Silicon Valley). Not sure what a "complete knockdown (CKD) kit" is, but US dealers will "hand assemble them locally." So who are these dealers? Bike assembly is frequently NOT done by the dealer mechanics - check your bike before riding! First production bikes due in June.
    2. Many parts are machined from solid aluminum plate. (No one in industry uses the term "billet." That's what amateurs and fanboys call machined aluminum parts.) Even if it's done more cheaply in China, it's still a low-volume (and rather wasteful) method, and it leaves a lot of tacky-looking machining marks. Lightning will have arrived when they start using more die castings.
    3. Lightning apparently builds their own motor (most likely from purchased sub-assemblies), and it's the only AC induction motor to my knowledge available on an EM. Forget what you thought you knew about electric motors in vehicles, because AC induction is a different animal. For example, the max 69 ft*lbs of torque is said to be constant from 1 - 15000 rpm. You can't do that with wound-field DC or PMDC motors. (It also gives you truly linear power, aside from programmed attenuation - see item #4.) I know very little about AC induction other than it is far more flexible (and complex to control).
    4. No TC. But they have highly variable torque delivery capability so they can shape how it puts down power pretty much any way they want. But it's not adaptable to varying conditions like TC. The regen is very mappable too. It remains to be seen how much of these adjustments are available to the end user. ABS is required in Europe, so I would hope it would be standard in the US too, but that was not specifically stated.
    #41
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  2. ctromley

    ctromley Been here awhile

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    Not sure, but it might be easier than you think on the Strike. The primary reduction and drive sprocket is outside the swingarm. (Which leads me to wonder about crash damage and how to protect from it.) It looks like there might be a removable section in the swingarm brace, allowing the belt to loop through. Seems pretty manageable.
    #42
  3. smdub

    smdub Adventurer

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    Die casting are cheaper but heavier for the same strength and has a lot of design limitations (wall thickness, draft, etc.) I would think most high end bikes just CNC extrusions at low volume. We spec both in the line of work I'm in (not motorcycles). You can media tumble or blast machinings to get rid of tool marks.
    Induction doesn't work like that. I used to do EV induction drives (for GM/Hughes & Ford/GE). Tesla uses induction. It will maintain a constant torque to the motor corner point. Basically identical to a PMSM to this point. But then you can enter field weakening and have a long region of constant hp. 3:1 not unreasonable. To put this in comparison, say you have a PMSM you gear for 150mph and lets say it makes a constant 100lbft. It will develop peak hp at top speed. For the same hp induction motor, you can gear the motor 3:1 lower (hp corner point at 50mph.) It will now deliver peak hp at only 50mph putting 3x the torque to the wheels (300lbft). From 50-150mph its constant hp. At 150mph its making the same hp as the PMSM was and delivering identical torque. In essence, the induction can beat the PMSM everywhere if the same size and rated hp. Now, nothing is really this simple. The above example assumes you can spin the induction motor 3x as fast which has its own problems. There is also an winding inductance w^2 term that comes into play at higher speeds and limits the constant hp range. In reality you don't design a system that can develop 3x the torque at low speeds. You could shoot for 1.5x as much and make some other tradeoffs to make the motor smaller. Low slip induction machines w/ Field Oriented Control aren't new (decades old technology) but they aren't as dead simple to control.

    There are other big advantages to induction. PMSM are always running max field. This causes large eddy current losses at partial load. 90% of the time you ride a bike you only need a tiny fraction of the avail power. Induction can easily field weaken to the optimal loss (where magnetic + resistive losses are equal.)

    Lets face it: motorcycle guys are NOT power electronics engineers. The control / throttle response of many e-bikes makes that abundantly clear. Even farming it out, the supplier may not really know what they are doing. (They are just successful in the industry because they keep doing what is 'good enough'.)

    FWIW, Heres the curve of the tesla model 3. You may notice the PMSM makes more torque but the induction spins faster. Remember what happens to the effective torque of the induction motor when you gear it to be the same as the PMSM. It will have more torque at almost every point than the PMSM.
    [​IMG]
    #43
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  4. ctromley

    ctromley Been here awhile

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    So for Lightning's claim to be true (assuming they were quoted correctly), the Strike motor would have to be operating entirely below its corner point. Is that possible?

    Also, that's not a power curve for a Tesla Model III. A Model III certainly doesn't peak at 700 W (0.94 hp), and to my knowledge it doesn't peak at 700 kW (~940 hp) either. (And a Model III probably spins way over 10k rpm.) It looks to me like a conceptual comparison between PM and ACIM? The rpm scale isn't marked, torque units aren't mentioned and there's no scale for them, so we can't really know what's being shown. But it ain't a Model III.
    #44
  5. smdub

    smdub Adventurer

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    Possible but unlikely as their own specs prove it. From the CN article linked yesterday they say 90kW @ 15krpm peak. Thats only 57Nm. To make the claimed 95Nm @ 15krpm would take 150kW(200hp).
    https://planetcalc.com/1908/

    Bringing up rpm... It can make sense to spin an electric motor faster and then gear it back down. Power is proportional to torque*speed. Torque is proportional to current*rotor diameter. So keeping everything else equal, the faster you spin the more power you make (or can make the motor half the size for the same power.) The EV2000 induction drive we used in the Ford/GE MEVP had a ~75kW continuous motor (peak was close to 2x.) The rotor was the size of a coffee can. Spun ~15krpm submerged in turbine oil for cooling, and had an integral ~5:1 planetary in the housing end bell. It connected to the car/truck driveshaft going straight into the rear diff directly. One person could pick up and carry around the little motor that ran a small pickup truck. Two(?) of them powered city busses.

    You are right. I googled for Tesla induction vs PMSM or something last night and grabbed the first appropriate looking graph w/o checking the scale or the full article it came from. My bad. But the general shape of the curves are still representative.

    All this shows we have a long way to go in the electric bike world. Hold onto your hats because there is more to come. I have an old email conversation archived w/ Bryan Parham at Zero back from 2010. Was trying to convince them to 1) offer a model w/ a sport bike like fairing and 2) go to AC (preferably induction) instead of DC. I have to admit it made me smile when I heard they finally went AC, even if it was PMSM, many years later.
    #45
  6. RCmoto

    RCmoto Long timer

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    #1 - assume a fairing would help with range, why did Zero opt. not to have one?
    #46
  7. smdub

    smdub Adventurer

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    No clear answer though a lot of the conversation revolved around cost. I had not seen a Zero in person but from the pictures knew they must be small. I had wondered if I could graft 250 sized race fairings on one. Back in my younger years I wouldn't have owned a bike w/o fairings. Now I'm much wiser and enjoy being naked;)

    I didn't see a Zero in the flesh until last year.
    #47
  8. kpinvt

    kpinvt OLDnSLO

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  9. _mtg_

    _mtg_ Been here awhile

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    It should certainly move electric motorcycles closer to the mainstream.
    However, it’s annoying that their teaser specs were misleading: $13k, 150 mile range, 150 mph. That range is only available in the higher end models. Same with top speed, albeit that matters far less unless you’re buying it as a race bike for a track with a long straight.
    #49
  10. dwenglis

    dwenglis Been here awhile

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    I think the enerigica ego is a better bang for the buck.
    140ish hp/lbs and 120 miles of range and a 18kish cost.
    #50
  11. T.S.Zarathustra

    T.S.Zarathustra Been here awhile

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    Reserve it here https://store.lightningmotorcycle.com/t/lightning-strike-reservation. With the KWh of batteries under 150$ for volumes of 1000 or more cells (Tesla reportedly pays under 100$ for the KWh) a price difference of 4000$ for 5 KWh difference between Standard and Mid Range is a bit high IMHO. Maybe there are other differences they don't mention.
    That does not detract from the fact that this is a very desirable bike, and a good step in the direction of making Electric Motorcycles compatible with midrange Internal Combustion Engine motorcycles.
    #51
  12. RedRocket

    RedRocket Yeah! I want Cheesy Poofs

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    Ohlins suspenders and more hp
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  13. T.S.Zarathustra

    T.S.Zarathustra Been here awhile

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    That is the difference between the Carbon edition and the Standard/Mid Range. I see nowhere mention of suspension or power difference between Standard and Mid Range. Only battery size, and weight, is mentioned.
    "Strike Carbon Edition is also fully configured with 120 horsepower, 180 lb-ft torque motor, 20 kWh battery and Level 3 DC fast charging as standard." "Additionally, Strike Carbon Edition is outfitted with Lightning’s Performance Package including top-level industry components Öhlins front and rear suspension, Brembo Monoblock"

    Strike-spec-table2-768x332.jpg
    #53
  14. ctromley

    ctromley Been here awhile

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    Assuming all that data is correct, how do they get an additional 5 kWh of energy to weigh only an additional 10 lbs? On a Zero SR, the Power Tank option adds (IIRC) 42 lbs. for only 3.6 kWh. Light weight costs money, so reducing weight elsewhere might make up the difference in cost.

    EDIT: I had another thought. With 180 ft*lbs. of torque, it's likely that keeping the front wheel on the ground is a real challenge. Maybe the Standard model carries ballast where there would be air in the battery box, just to help keep the front wheel down? I know, it sounds like crazy talk, but 180 ft*lbs may very well demand crazy solutions to make the thing rideable. No one wants to loop a Strike on the test ride.
    #54
  15. ctromley

    ctromley Been here awhile

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    So the Electrek article is out. But the Lightning site only has a side view pic of the Strike, no other info. There's nothing in my inbox either, and I'm on their list. There are lots of questions unanswered. No descriptions, no gallery photos, a video that provides no new info (and frankly looks like it was done on-the-cheap), no FAQs, very limited specs, no "where to buy" feature. That last one's a big issue.

    I'm perfectly capable of having a Strike delivered to my house, assemble it myself and do all service for years to come. I can install normally dealer-installed upgrades. Assuming the need for special diagnostic tools is not too great, I can work in concert with their tech support to work out any head-scratcher issues that might arise. But what if I have a warranty claim? Are they going to pay me for my labor? And how the [bleep] are they going to handle a recall? Pay me for that too? That would work for me, but what would most other people do? How does Lightning know I have any idea what I'm doing? How many of you would be comfortable getting up close and personal with the high voltage stuff? Is there a shop manual, and how detailed is it? Is it Very Thorough about how to work safely with high voltage?

    Throughout the entire tease, not one word has been mentioned about dealers. It's an issue that will make or break the success of the Strike. What's up, Lightning? Electrek says now first deliveries are in July. Are you still lining up dealers?

    EDIT: I still think regional warehouses along with 'dealers on wheels' (service and test rides by appointment) could be a very workable alternative. Even highly attractive, eliminating dealer markup, keeping profits up and selling price down, while ensuring customers are treated the way Lightning wants them to be treated. The dealer business model is soooo 20th century.
    #55
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  16. ctromley

    ctromley Been here awhile

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    Uh, no passenger pegs? Or any likely place to mount some? I almost never carry a passenger, but don't like the idea of never being able to. Seems to me that would be a deal-breaker for many. Maybe they have some clever add-on package?
    #56
  17. ctromley

    ctromley Been here awhile

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    180 ft*lbs of torque?!?!?!? Available at just about any speed? Why didn't they put that in the teaser?

    Years ago I read a test about some uber-power bike (ZX-14?) where they said you need to be very sure the bike is pointed where you want it to be before you whack the throttle open - because you will be there before you can make any corrections. I thought it was a clever bit of hyperbole. I'm thinking it will apply in spades on the Strike, and needs to be a serious piece of advice to anyone taking it for a spin. (A ZX-14 has 64% of a Strike's torque and is 27% heavier.) Can't wait to see the 40-60 and 60-80 mph roll-on times.

    Holy shamoley - this is a bike that should keep you Very Alert.
    #57
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  18. _mtg_

    _mtg_ Been here awhile

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    According to my lady, lacking a passenger seat on a sport bike is no problem :)
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  19. Madrodo

    Madrodo Adventurer

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    Öhlins suspension, top of the line Brembo brakes, carbon fiber fairing, DC charging (full charge in 35 minutes).
    #59
  20. ultrarnr

    ultrarnr Been here awhile

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    The Strike Carbon Edition has a much larger battery than the Energica Ego yet weighs 145 pounds less. Really curious how they did that.
    #60