Author Topic: Comparing the Empulse with the 2013 Zero  (Read 5551 times)

Gavin

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Re: Comparing the Empulse with the 2013 Zero
« Reply #30 on: January 29, 2013, 05:24:30 PM »
Don't underestimate the importance of the clutch...at least for this generation of rides (and likely one more after this one)...

The stick shift (all my cars have had one) is almost dead in the US, except for sport enthusiasts.

But most motorcycle riders are sport enthusiasts and like the clutch (ride a scooter and see the reception you get from motorcycle riders---I know first hand being an old scooter guy). If it doesn't have a clutch, it ain't a motorcycle.**

Now many new riders won't care. Heck many old riders won't care. Twist and go has it's advantages. But without a clutch many of the current riders won't go near an electric...

That will change...as people change...and as the performance of higher voltage becomes affordable.

But it's good to have a clutch version now. Heck, in the future it will still be nice to have a TnG and Clutch version. Some people will always want a clutch.

But, like stick shift cars, in 20 years---90 percent of EV motorcycles will likely be clutchless.

of course in 20 years I better have my flying motorcycle....and some depends...sigh...

Gavin

**this attitude will, and is even now, slowly changing.

ps...i do like that the Empulse is kinda Clutch for highway and twisties, TnG for the city (yes you can still shift in the city is you want...or not if you don't...a win win)


« Last Edit: January 29, 2013, 05:41:35 PM by Gavin »

protomech

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Re: Comparing the Empulse with the 2013 Zero
« Reply #31 on: January 29, 2013, 07:12:01 PM »
I think I guesstimated the Empulse concept 0-60 time at 6-7s from an old track video. That's acceptable from a track perspective (how often do you use 1st gear on a track?), but not on the street if you claim sporting aspirations.

IET vs direct-drive is a funny comparison. Which solution wins depends on what you look at.

If you fix power (say, 40 kW) then IET is both quicker to 60 mph and has a faster top speed. At least given performance claims.. a comparison review should sort this out quickly.

Fixing power seems like a somewhat artificial limitation; in practice it may be necessary, as there is not a great wealth of top-tier motors to choose from.

If you fix weight, cost, development time, or packaging volume.. then it's not so clear to me as a bench-racer. I suspect a 2013 Zero S with a Size 6 controller upgrade and 105 mph gearing would perform head-to-head with the Empulse .. I'm a little mystified tbh that the Zero S appears to spec a size 4.

Regarding rear wheel gearing.. need to see if I can find the 2013 Zero gearing. 2012 S is 132T/28T, 57 Nm @ motor output .. so 270 Nm rear wheel torque.

Edit: 2013 S appears to use the same rear sprocket as 2012. Say same 132T/28T gearing.

2012 S .. 132T/28T .. 57 Nm motor .. 270 Nm wheel .. 340 lb bike + 180 lb rider = ~9s 0-60
2012 DS .. 132T/25T .. 57 Nm motor .. 301 Nm wheel .. 340 lb bike + 180 lb rider = ~8s 0-60
2013 S .. 132T/28T .. 92 Nm motor .. 434 Nm wheel .. 350 lb bike + 180 lb rider = ~5.5s 0-60
2013 Empulse .. ~10:1 1st gear .. 81 Nm motor .. 800 Nm wheel .. 470 lb bike + 180 lb rider = ~3.7s 0-60

Quick envelope calculations, anyways.
« Last Edit: January 30, 2013, 03:30:12 AM by protomech »
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BrammoBrian

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Re: Comparing the Empulse with the 2013 Zero
« Reply #32 on: January 29, 2013, 08:47:36 PM »
IET vs direct-drive is a funny comparison. Which solution wins depends on what you look at.

We think the IET wins over direct drive on acceleration, top speed, and efficiency over a range of real world riding conditions.

If you fix power (say, 40 kW) then IET is both quicker to 60 mph and has a faster top speed. At least given performance claims.. a comparison review should sort this out quickly.

Fixing power seems like a somewhat artificial limitation; in practice it may be necessary, as there is not a great wealth of top-tier motors to choose from.

The power level is not "fixed" based on available motor technology.  It's "fixed" based on inverter cost and the limits of a less expensive Mosfet based motor controller, like the Sevcon.  To state it another way - around 40-45kW is the best "bang for the buck" with current (ha!) technology. 

We have built 60 - 120kW direct drive bikes that perform well in acceleration and top speed, but require the use of a high voltage, very expensive,  IGBT based motor controller.   The IET is the ideal solution as it provides the maximum performance for the minimum cost, something I hope our customers can appreciate.

   
If you fix weight, cost, development time, or packaging volume.. then it's not so clear to me as a bench-racer. I suspect a 2013 Zero S with a Size 6 controller upgrade and 105 mph gearing would perform head-to-head with the Empulse .. I'm a little mystified tbh that the Zero S appears to spec a size 4.

Believe what you like, but I know who I'd put my money on... ;)


protomech

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Re: Comparing the Empulse with the 2013 Zero
« Reply #33 on: January 30, 2013, 03:14:43 AM »
Really nice motors do seem to require unobtanium controllers, but is there really a wall at 40 kW? Curtis and Sevcon both offer MOSFET controllers that should support a 60 kW motor (at the 2 minute rate).

Nuts & Volts commented on esbk.co:
Quote
I would guess that the new Zero is probably using a Size 6 as well, but I’m just speculating there. Also keep in mind the Brammo Empulse use a Parker liquid cooled motor (142mm dia, maybe 120mm long) and the Zero S uses a air cooled custom motor (maybe 200mm dia, and maybe 150mm long). The Zero motor is large so it can handle decent continuous power. Maybe 10-15kW, but the Brammo motor is probably good to do 15-20kW continuous.

Supposing the dimensions are accurate, seems like Zero is going a big air-cooled motor / small controller approach .. where Brammo is going a little liquid-cooled motor / big controller approach. Same peak power. Zero should punch quite a bit harder, at least peak, if they also packaged a bigger motor controller.. but presumably there are technical (packaging? durability? weight?), cost, or strategic reasons why they choose not to do so.

70-80 kW peak with 100V MOSFET is probably the limits of the tech, but that seems to be doable looking at Curtis 1238 and Sevcon Size 6 motor controller specs.

A motor with transmission is always more flexible and can punch harder than the same motor without a transmission, ignoring losses .. basically it can always operate at high voltage / high current. Is it just cooling (controller + motor) that gradually reduces power? Is the Empulse output 40 kW continuous until the battery is fully depleted? Or perhaps more apropos, can the Empulse run flat out on a track without thermal limiting?

A bigger motor / controller direct drive system can operate at medium voltage / very high current at either low or high speeds where it's outside its peak power region. Not sure air cooling will cut it here. Presumably liquid cooling + a sufficiently large radiator would similarly prevent thermal cutbacks.

Do you see IGBT controllers getting less expensive in the next 2-3 years? I think higher voltage pack issue will be forced at some point for 20+ kW rapid charging, at least on certain niches. I recall many (all?) of the car EVs are using IGBT controllers .. will that eventually drive down component cost for bikes as well?

For 2013 performance my money is on the Empulse too. I'm looking forward to the races, I'm very curious to see how the weight difference plays out .. and how both bikes handle thermals.

For 2014, the Energica promises to provide a big motor / big controller direct drive counterpart to the Empulse and IET. I think $23k is optimistic .. but would love to see them meet their timeline and price point.

Edit: reworded, what a load of gibberish.
« Last Edit: January 30, 2013, 12:30:45 PM by protomech »
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Richard230

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Re: Comparing the Empulse with the 2013 Zero
« Reply #34 on: January 30, 2013, 10:39:34 AM »
Speaking of cost, my guess is that Zero is making more profit per unit than Brammo.  Zero does not have to pay for a transmission and associated components and their frame (I have seen them in the shipping boxes), which is made in China, looks relatively simple and easy to manufacture, compared with the frame Brammo uses on the Empulse.  I am pretty sure that the European suspension components used by Brammo are more expensive than the Fast Ace (made in Taiwan) components used by Zero.  Finally, even the Zero's wheels and tires likely also cost less than the ones used by Brammo.

Then you also have the lower overhead that Zero probably enjoys.  I have seen their factory and it is just a warehouse with offices, a large parts storage area and a small area for assembling the bikes, using hand labor and small tools. The entire company seems to keep a sharp eye on low production and overhead costs in order to maximize the "bottom line".  If I had to guess, I would say that Zero is probably making at least twice the profit per unit (whatever that is) than Brammo can, when comparing the prices of Empulse with the premium version of the 2013 Zero S.
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Re: Comparing the Empulse with the 2013 Zero
« Reply #35 on: January 30, 2013, 04:00:55 PM »
I can remember that at the time of the Vectrix chapter 11 someone calculated that the bikes they made up to that point were over $100.000 each. So it will take a long time for Zero or Brammo to recover all the R&D costs. You need to be in this business either for the long term or aim to get bought/IPO.

On the IGBT topic, Vectrix developed their own MC (which uses IGBT's). maybe Zero or Brammo will go there also. I guess Zero doing their own motor is one step in that direction.
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BrammoBrian

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Re: Comparing the Empulse with the 2013 Zero
« Reply #36 on: January 30, 2013, 05:14:25 PM »
Really nice motors do seem to require unobtanium controllers, but is there really a wall at 40 kW? Curtis and Sevcon both offer MOSFET controllers that should support a 60 kW motor (at the 2 minute rate).

70-80 kW peak with 100V MOSFET is probably the limits of the tech, but that seems to be doable looking at Curtis 1238 and Sevcon Size 6 motor controller specs.

A motor with transmission is always more flexible and can punch harder than the same motor without a transmission, ignoring losses .. basically it can always operate at high voltage / high current. Is it just cooling (controller + motor) that gradually reduces power? Is the Empulse output 40 kW continuous until the battery is fully depleted? Or perhaps more apropos, can the Empulse run flat out on a track without thermal limiting?

Do you see IGBT controllers getting less expensive in the next 2-3 years? I think higher voltage pack issue will be forced at some point for 20+ kW rapid charging, at least on certain niches. I recall many (all?) of the car EVs are using IGBT controllers .. will that eventually drive down component cost for bikes as well?

For 2013 performance my money is on the Empulse too. I'm looking forward to the races, I'm very curious to see how the weight difference plays out .. and how both bikes handle thermals.

For 2014, the Energica promises to provide a big motor / big controller direct drive counterpart to the Empulse and IET. I think $23k is optimistic .. but would love to see them meet their timeline and price point.

The motor size between these bikes is not very different, so I don't follow the "big motor" / "small motor" argument.  The Parker motor was developed here at Brammo (with no government funding, thank you!) and offers higher peak and continuous performance.  It is also lighter, so the specific power is higher.


Sorry, a Sevcon Size 6 cannot output 60kW and certainly not 70-80kW and I think this is the "trap" you tend to fall into by bench racing with datasheets.  You cannot simply multiply the rated voltage by the rated current and determine the power output.  It might be able to deliver higher than 40kW for a small period of time, but only if connected to a power supply rather than a battery pack that has impedance and voltage sag. 

I do see high voltage motor controllers becoming less expensive over the next few years, but the ones used in the automotive world are typically too large for our application.  Also, don't assume that just because the auto industry is doing it that it's cheap.  The OEMs have the ability to subsidize some pretty amazing costs. 

I'm glad you've got your money on the right team... ;)
« Last Edit: January 30, 2013, 05:16:50 PM by BrammoBrian »

flar

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Re: Comparing the Empulse with the 2013 Zero
« Reply #37 on: January 30, 2013, 05:28:03 PM »
Thanks for all of your clarifications Brian (and your analysis, proto, that is laying all of the details on the table).

I guess I should stop telling people that I feel that the transmission might be a short-term solution to today's problems.

But, one thing I'm curious about - some of your explanations as to the value of the transmission are based on the cost of various components.  And costs tend to be subject to economies of scale.  Clearly we are seeing a great growth in this industry in terms of the viability of electric motorcycles.  What kind of change in the economies of scale might need to happen for us to see the equation change in your mind?  What kind of a market size might make the added costs and R&D for a motor that was capable of sportbike performance via direct drive feasible in a (mass-produced) production bike?  Or is this not a question of "economies of scale" at all?

And I was also under the impression that "Parker motor" meant it was sourced from a company named Parker, but I guess that is an internal project name?
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Gavin

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Re: Comparing the Empulse with the 2013 Zero
« Reply #38 on: January 30, 2013, 05:34:01 PM »
No, you were right the first time....

Parker is a motor company separate from Brammo...they have a close relationship it seems and they worked together on the Empulse motor...

Gavin

http://www.parker.com/portal/site/PARKER/menuitem.14ecfc66e7a40c1af8500f199420d1ca/?vgnextoid=43cb5242ade5c110VgnVCM10000032a71dacRCRD&vgnextfmt=default&Keyword=MOTORS&Wtky=MOTORS
« Last Edit: January 30, 2013, 05:37:20 PM by Gavin »

protomech

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Re: Comparing the Empulse with the 2013 Zero
« Reply #39 on: January 30, 2013, 05:45:00 PM »
I calculate the Sevcon G8055 output like so:

V_rms = 116V (max) /sqrt(2) = 82V
A_rms = 550 (2 minute rating, assuming this is phase current)

Motor power = V_rms * A_rms * sqrt(3) * power factor * efficiency

I don't have any good numbers for power factor and efficiency, so going with an optimistic 0.9 for each.

82 V * 550 A * 1.732 * 0.9 * 0.9 = 63.3 kW (2 min rating .. 10s rating would be 76 kW)

Say the battery is 28s 90Ah, charged up to 4.2 volts per cell, further suppose that under 6+C load it sags down to 3.2 volts per cell, 90V.

Then motor output is 90 / sqrt(2) * 550 * 1.732 * 0.9 * 0.9 = 49 kW.

Is the spreadsheet math and the assumptions remotely close to right?

Is controller performance dropoff just due to thermals?
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Richard230

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Re: Comparing the Empulse with the 2013 Zero
« Reply #40 on: January 30, 2013, 06:23:54 PM »
Yesterday, in a December video review of the 2012 Zero S, I heard mention that the British motorcycle magazine, Bike, was testing the 2012 ZF9 Zero S and their review would be included in their January issue. So today I rushed down to my nearest Barnes and Nobel and picked up the last remaining and well-read copy that they had on their news stand.

The Zero review, written by Martin Fitz-Gibbons, covers 6 full pages, over half of which consists of color photos.  Unfortunately, much of the review talks about the author's first ride on the bike and his difficulties in locating a charging station.  All of the charging stations, except for one, were being hogged by IC cars and trucks and in one case the truck was actually occupied by a tradesman who refused to move.  A couple of other charging stations were broken and one station not only didn't work, but it would not release his charging handle after he plugged it in and tried to remove it when his bike wouldn't charge.  Calling the “help” line did nothing but refer him to the store on whose property the station was located and they had no idea what to do about the malfunctioning outlet.  After going through all that drama, there was little space left for an actual description of the Zero.

But here are some of the review comments that were provided, which do not consist of repeating the specifications: Their estimated range for the 9 kWh bike is 55 miles in normal riding. No instrumented acceleration data was provided, but the reviewer commented that the Zero would accelerate from a stop to 30 mph in about 4 seconds and take about another 4 seconds to reach 60 mph. No ¼ mile times were provided. Steering geometry is said to be “sharper” than that of a Triumph Street Triple R. The bike's weight and performance most closely resemble the KTM 200 Duke.

The author says:  The lessons are clear: even if electric bikes were ready for Britain, Britain isn't ready for electric bikes. Public charging might work in cities with a plentiful (charging) network, but they can't be relied on rurally.”

The Zero was taken to a road-bike only trackday, after a 70-mile ride to the racetrack, carrying a second charger in the rider's backpack.  A few hours of rapid-charging in the pits gave enough juice for five laps in the morning and a further four laps in the afternoon, leaving enough time to top up for the return journey home.  The author says: “While there's certainly not much to shout about on the track, it does prove capable of 170 miles over the full day. And in case you're wondering, it passed the noise test.”

The article continues: “Still, there's something utterly intoxicating about the Zero. It's the novelty of it being so radical. Electric power evokes a wide-eyed wonder. It takes you back to the glorious sensation of twisting a petrol bike's throttle and feeling it move for the very first time.”

After a paragraph discussing the pros, cons and potential future of electric motorcycles, the article concludes with: “As it stands today the Zero S ZF9 is fast enough to flow through traffic and has enough of a range for everyone on Bike to do their daily commutes. It is also the most fascinating, exciting and original bike I have ridden in many years and the one I'm most upset to hand back at the end of the test.”

Attached is a photo of the power and torque chart produced on the magazine's dyno.
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BrammoBrian

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Re: Comparing the Empulse with the 2013 Zero
« Reply #41 on: January 30, 2013, 10:59:03 PM »
I calculate the Sevcon G8055 output like so:

V_rms = 116V (max) /sqrt(2) = 82V
A_rms = 550 (2 minute rating, assuming this is phase current)

Motor power = V_rms * A_rms * sqrt(3) * power factor * efficiency

I don't have any good numbers for power factor and efficiency, so going with an optimistic 0.9 for each.

82 V * 550 A * 1.732 * 0.9 * 0.9 = 63.3 kW (2 min rating .. 10s rating would be 76 kW)

Say the battery is 28s 90Ah, charged up to 4.2 volts per cell, further suppose that under 6+C load it sags down to 3.2 volts per cell, 90V.

Then motor output is 90 / sqrt(2) * 550 * 1.732 * 0.9 * 0.9 = 49 kW.

Is the spreadsheet math and the assumptions remotely close to right?

Is controller performance dropoff just due to thermals?

Michael,

You're pretty close.  Here are some comments from our lead motor guru, Dan Riegels:

Power factor is way too high, closer to 75% at Pmax.  Efficiency is good.  The only limitation is cooling.  The 2min and 10sec rating are assuming a certain level of cooling.  Voltage sag quoted is closer to 5C+.  Low PF puts a lot of load on the controller.

I would tell you more... but then I'd have to either hire you or kill you... ;)

BrammoBrian

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Re: Comparing the Empulse with the 2013 Zero
« Reply #42 on: January 30, 2013, 11:11:18 PM »
No, you were right the first time....

Parker is a motor company separate from Brammo...they have a close relationship it seems and they worked together on the Empulse motor...

Gavin

Parker is Parker-Hannifin Corporation.  The GVM motor's development goes back to our initial race bike work with them back in 2010.  Piece of trivia for you - Parker also developed the PMAC hub motor and IGBT based motor controller for the Vectrix Maxi-Scooter.  Here are some better links:

http://www.parker.com/portal/site/Market-Tech/menuitem.e9f921bc8ae21676de92b210237ad1ca/?vgnextoid=896a58fc51cb8210VgnVCM10000048021dacRCRD&vgnextfmt=default

http://www.parker.com/literature/SSD%20Drives%20Division%20North%20America/Case%20Studies%20and%20White%20Papers/BrammoDaytona%20article%20by%20Parker.pdf

BrammoBrian

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Re: Comparing the Empulse with the 2013 Zero
« Reply #43 on: January 30, 2013, 11:34:13 PM »
Thanks for all of your clarifications Brian (and your analysis, proto, that is laying all of the details on the table).

I guess I should stop telling people that I feel that the transmission might be a short-term solution to today's problems.

But, one thing I'm curious about - some of your explanations as to the value of the transmission are based on the cost of various components.  And costs tend to be subject to economies of scale.  Clearly we are seeing a great growth in this industry in terms of the viability of electric motorcycles.  What kind of change in the economies of scale might need to happen for us to see the equation change in your mind?  What kind of a market size might make the added costs and R&D for a motor that was capable of sportbike performance via direct drive feasible in a (mass-produced) production bike?  Or is this not a question of "economies of scale" at all?

I don't view the transmission as a short-term solution at all.  Even with a high-voltage system, the ideal solution in my mind (although there are many others that would disagree) would still incorporate a multiple ratio gearbox (maybe or maybe not 6 gears).  It's very good way to get significant torque production with a smaller overall system.  A direct-drive, high voltage system would be "good-enough" for most riders, but it would still not maximize the available performance (again - my opinion). 

Regarding economies of scale, it's hard to judge, but there are some options that may significantly reduce costs over the next 5-10 years.  As for purchasing IGBTs, I've heard that you can't really impact the price at less than 1,000 units per month.  As I believe would be true with any motorcycle OEM, the golden unit volume is 10,000 per year.  This makes additional investment in the platform easily justified based on how small the amoritized cost of the development is. 

As always, Brammo will endeavor to provide our customers with the best value (which I agree is subjective) of performance for cost using the best technologies that we are aware of.  It is true that other OEMs may be using cheaper components and making more profit off their customers, which I'm fine with.  My hat's off to them if that's what makes them (or their investors) happy.  We'd like to focus on building a quality product first and a solid brand reputation off of that. I would be disappointed if our customers sat on the Empulse and thought to themselves... "Wow, Brammo is making a ton of profit on this... "

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Re: Comparing the Empulse with the 2013 Zero
« Reply #44 on: January 30, 2013, 11:39:27 PM »
Quote
I would tell you more... but then I'd have to either hire you or kill you...


You should hire him :)

G