ElectricMotorcycleForum.com
Makes And Models => Zero Motorcycles Forum | 2013+ => Topic started by: dicknose on July 22, 2014, 01:42:32 PM
-
Had a test ride on a new S model. Of cause the SR the next day so I didnt get to do a back to back test.
Quite enjoyed the ride, interesting sensation not having to worry about gears.
And I thought the mid speed punch was quite reasonable.
But was a bit surprised by its "off the line" performance, it seemed very slow.
I had it in sports mode and gave it a fair bit of throttle and it moved away ok, but it was just that "moved away", not "leapt away"
I was expecting an electric bike to have really good performance down low and was a bit underwhelmed.
Happy to admit Im used to powerful bikes and wasnt expecting this to be the equal of my 1200cc bike.
But it seemed sluggish at low speeds.
Is this typical? Is it some sort of design decision because it doesnt have traction control?
Anyway trying to get back to the dealer to try the SR.
But they are over an hour away and a bit tricky to sneak off from work for a test ride.
Im keen to get one as a commuter, so that means plenty of traffic light GPs and slow speeds.
Hoping the SR feels a bit more fun at slow speeds.
-
I tried both the SR and S before deciding on the SR.
You're right the S is lacking in low down acceleration (<20mph). The Zero SR is much better in that regard but Zero has still limited the available torque at low speeds for whatever reason - safety, stress on components etc.
After trying the Zero S I was underwhelmed after coming off the SR. Test riding the Zero SR you won't be disappointed and its pull from 20-50mph would match many 600cc bikes out there.
-
It seems a design thing to prevent issues with the motor, the belt or the controller. Anybody can confirm this?
-
I dont know what city dicknose commutes in, but when I was in Rome last year, even the smallest gas scooters would out-accelerate commuter traffic in the 0 to-the-next-stoplight race.
-
My traffic light GPs are with other bikes! Not cars.
I dont need to win the stoplight race, but I dont want to get run down by the bikes behind me.
Or lose to a scooter!
Plus its fun having the arms pulled a bit longer!!
My current bike is a Ducati Diavel, previous bike Honda CBR1000RR
So Im used to quick bikes!
I did ride a Z800 thru Italy/Switzerland last year (but not Rome)
Hopefully I can swing the SR test ride later this week.
Then if the grin is big enough, the Zero will join the Ducati in the garage and be my daily ride.
Give the Ducati a rest, it uses fuel, but also tyres and servicing are big expenses (and a pain to get done - tyres last about 3-4 months)
As for the initial torque, I was hoping someone was going to say "its electronically limited" and that people had work arounds.
With my bulky weight I need a bit of extra oomph (I weight more than the Repsol Honda MotoGP riders - combined)
Thanks for the replies so far.
Anything else a newbie needs to be aware of?
I saw a thread about possible/likely ABS next year - that would be nice. Even more so if it mean traction control.
Maybe - whats the most annoying thing about the bike?
(and dont say - everyone stopping to look and ask questions about it!!)
-
whats the most annoying thing about the bike?
Charge times, its they one thing that most EV's still need to get sorted out, but the Zeros really could do with a stronger on-board charger as standard.
-
It is my belief that the performance of Zero motorcycles is electrically limited by the controller's programming. My 2014 S, that weighs 440 pounds is about twice as fast off the line as my 2012 S was, which weighed 100 pounds less. Over about 20 mph, both bikes would really take off. I believe that Zero deliberately reduces the available torque when moving off from a stop in order to keep the rear wheel from spinning on slippery pavement, as well as to protect the drive train components. I think they are still trying to get the right amount of power and regen braking effect with their new models that will conform to their thoughts about rear wheel traction.
-
It's pretty clear to me that they limit the torque at very low speeds on my SR. It pulls well but it's certainly not going to light the tire unless you have the front brake on. I'm assuming it's to keep the belt from snapping and to keep the rear wheel from going up in smoke. They use a fairly skinny tire out back, considering the performance level of this bike, to reduce rolling resistance and maximize range, and it just doesn't get the same amount of traction the wide tires on other sport bikes gets.
I do wish, on the SR at least, they'd put a wider belt and a wider tire on the bike, and not limit the startup torque so much. This IS the dragster in the stable, not the efficiency king.
-
If off the line acceleration is important than you must also try the Brammo Empulse.
Due to the use of a gearbox it launches off the line better than anything. Just make sure it's in sport mode.
-
If off the line acceleration is important than you must also try the Brammo Empulse.
Due to the use of a gearbox it launches off the line better than anything. Just make sure it's in sport mode.
I rode a friend's 2013 Empulse. It doesn't launch any harder than an SR, and the SR pulls away from it at anything above 15 mph or so, gearing or no gearing. I do like the Empulse's onboard Type II charger, though I don't know if I'd wind up using it very often. The real difference for me was in the simplicity of the Zero's design -- no tranny to fail or to require lubrication, no water cooling system, and lighter weight because of those things. A battery, a controller, a motor, a rubber band, the rear tire. It just seems elegant and reliable.
And the higher performance ain't bad, neither!
-
Was that in sport mode on the Empulse?
I am a bit surprised because even my E1 launches better than the Zero.
I have a colleague that has a Zero SR. Next month we go riding together. I will make sure we do some drag races to find out at what speed exactly he overtakes me!
-
Zero Motorcycles have no transmission and therefore you are taking off from the line in top gear.
They do sell a different front sprocket if you want to sacrifice top speed to gain off the line performance.
It is also woth noting that with a Zero all launches are equal as there is no clutch or shifting required.
In some fool hearted drag races between my FX and friends bikes it is interesting to see that when their clutch levers come back the FX launches ever forward while they are changing gears.
-
My 8.5 2013 S accelerates enough to spin the tires on takeoff. Zero to 60 mph time is 4.8 seconds and as you accelerate away, you can feel the tires on the edge of wanting to skip. With the SR, the zero to 60 time is 3.3 sec., but it has the same size tires. Maybe a different brand though. The added weight of the SR must help keep the tires stick to the pavement too. Personally, I prefer the lighter bike. I am not sure how the SR can be so much faster than the S and still keep the tires on the pavement with the same relatively skinny tires.
-
I am not sure how the SR can be so much faster than the S and still keep the tires on the pavement with the same relatively skinny tires.
Hence my belief that Zero "de-tuned" the bottom end a bit on the SR, as well as going with a larger sprocket to reduce the torque multiplication slightly. I'm sure it reduces the load on a lot of things, not the least of which is the belt, but I think it also helps keep the rear tire from going up in smoke, and helps keep the front wheel on the ground.
Personally, I don't have a problem with those last two things -- I'm a heavy guy, which gives the rear tire more traction and more "ballast" to keep the front wheel down. Of course, it's not exactly good for 0-60 times, but my bike is plenty quick for me, even hauling my butt around.
-
Check out this nice little bit of research done by Ted Dillard
http://evmc2.wordpress.com/2014/07/07/motor-starting-torque-stall-torque-and-motor-types/ (http://evmc2.wordpress.com/2014/07/07/motor-starting-torque-stall-torque-and-motor-types/)
I also find the comments enlightening.
-ryan
-
I'd imagine someone like Harlen, or Electric Cowboy, would know more about how much, if any, soft start is in the verious Zero's. As I believe they are both capable of programming the Sevcon controllers on the bikes.
-
Wait, now I'm getting confused. I thought the secret sauce for Zero's new generation of motors was to essentially invert the usual construction by mounting the coils to the outside housing (the stator), where they can be cooled more easily, and mounting the magnets to the rotor. Doesn't "permanent magnet" mean "DC motor" in electric motor world? In other words, I thought Zero used PMDC motors?
Somebody please correct me if I'm wrong.
-
Zero does use DC motors. Seems someone is/was confused.
-
Zero used to use PMDC motors (Motenergy and Agni motors) paired with Alltrax controllers. PMDC motors have coils on the Rotor and magnets on the stator. DC voltage goes to the motor. PMDC motors use mechanical commutation by using brushes to switch the magnetic fields.
All of the new generation Zero's (Sevcon-controlled motors) are PMAC, meaning Permanent Magnet AC, commonly referred to as Synchrounous AC motors. PMAC motors have magnets in the rotor and coils on the stator. These motors use an AC controller (or inverter) that converts the DC to AC. PMAC motors use Electronic commutation by using the controller to switch the magnetic fields, so no brushes.
-
All of the new generation Zero's (Sevcon-controlled motors) are PMAC, meaning Permanent Magnet AC, commonly referred to as Synchrounous AC motors. PMAC motors have magnets in the rotor and coils on the stator. These motors use an AC controller (or inverter) that converts the DC to AC. PMAC motors use Electronic commutation by using the controller to switch the magnetic fields, so no brushes.
My understanding of electric motor configurations is pretty meager, but I thought what you're describing is referred to as a "brushless DC" motor. Whatever you call it, it doesn't seem like it should suffer from low torque at low rpm. The magnetic field from the magnets is fixed, and you can generate full-strength magnetic fields from the coils even when the motor's stalled out (or just starting to turn), so you should have maximum torque available at 0 rpm. I thought the reduced torque in AC motors was related to the field coils; a PM motor doesn't have any of those issues.
Then again, I could be completely HUA here. I'm an EE so I could probably build you a pretty decent controller, but I definitely don't qualify as a motor expert.
-
Thanks for the link, Biff!
On the specifics of AC motors, this is about the most informative page I've been able to find:
http://machinedesign.com/motorsdrives/difference-between-ac-induction-permanent-magnet-and-servomotor-technologies (http://machinedesign.com/motorsdrives/difference-between-ac-induction-permanent-magnet-and-servomotor-technologies) Maybe that will help (though a lot of it is way over my little non-EE or E-anything brain).
As I learned in putting my post together, the starting torque is pretty important in your "launch" performance, and from the specs I've been able to compare the AC motors, whether with permanent magnets or not, do have lower numbers for that.
-
All of the new generation Zero's (Sevcon-controlled motors) are PMAC, meaning Permanent Magnet AC, commonly referred to as Synchrounous AC motors. PMAC motors have magnets in the rotor and coils on the stator. These motors use an AC controller (or inverter) that converts the DC to AC. PMAC motors use Electronic commutation by using the controller to switch the magnetic fields, so no brushes.
My understanding of electric motor configurations is pretty meager, but I thought what you're describing is referred to as a "brushless DC" motor. Whatever you call it, it doesn't seem like it should suffer from low torque at low rpm. The magnetic field from the magnets is fixed, and you can generate full-strength magnetic fields from the coils even when the motor's stalled out (or just starting to turn), so you should have maximum torque available at 0 rpm. I thought the reduced torque in AC motors was related to the field coils; a PM motor doesn't have any of those issues.
Then again, I could be completely HUA here. I'm an EE so I could probably build you a pretty decent controller, but I definitely don't qualify as a motor expert.
I was more commenting as to the terminology, I appologize.
I wanted to illustrate the differences before starting to understand how the motors and controllers work. I've heard people use BLDC and PMAC interchangeably, but BLDC are actually slightly different. They're wound such that they have a Trapezoidal back-emf profile, and the poles stick out from the stator to concentrate the flux and the controller uses a pulsed DC waveform. I don't see BLDC used a lot in drive applications anymore, not with Sinusoidal drives widely available. In contrast, PMAC or Synchronous AC motors are wound such that the back-emf profile is sinusoidal and the controller uses a true Sinusoidal waveform.
More on BLDC and PMAC:
http://www.mpoweruk.com/motorsbrushless.htm (http://www.mpoweruk.com/motorsbrushless.htm)
The reduced starting torque in AC motors mainly when using Induction motors, which require an electric field to induce a current (and in-turn a magnetic field) in the rotor. Both PMAC and AC Induction have "field coils" referred to as the "stator".
More on Induction (and Synchronous AC) here:
http://www.mpoweruk.com/motorsac.htm (http://www.mpoweruk.com/motorsac.htm)
Back to the original discussion about slow acceleration:
I know from looking at the Sevcon in the Brammo, that there are profiles inside the controller. I don't have a Zero to play with, but I assume that they're doing something similar with limiting the current a little at startup for safety reasons, as well as trying to stay below the force required to snap belts.
Another thing, is that you've got a gear ratio that must suit all speeds between 0 and 100mph (or whatever the Zero is). While you may produce the most torque at 0RPM, your gearing is set up such that you can reach 100mph. If you had a small gear ratio, the acceleration will be terrible until you hit the power band of the motor (max HP). If you had a high gear ratio, you'll accelerate like a bat out of hell, but you may not ever be able to hit 100mph because the max RPM of the motor might occur before then.
I'm thinking its a combination of the two. Because zero chose transmissionless, they're limited to some degree as far as gear ratios. I think some of it is also safety and trying not to break belts/pull the bike out from under you.
-
Another thing, is that you've got a gear ratio that must suit all speeds between 0 and 100mph (or whatever the Zero is). While you may produce the most torque at 0RPM, your gearing is set up such that you can reach 100mph. If you had a small gear ratio, the acceleration will be terrible until you hit the power band of the motor (max HP). If you had a high gear ratio, you'll accelerate like a bat out of hell, but you may not ever be able to hit 100mph because the max RPM of the motor might occur before then.
Agreed. Lower (numerically higher) gearing gives you a higher torque multiplication factor, so more torque, but only at lower speeds since the motor will spin out faster. At the high end, the top gear should allow the motor to wind to its highest-horsepower rpm just as the aerodynamic/rolling resistance equals that horsepower output.
On the Zero SR (my bike), the single gear is arranged so the motor spins out just as it's hitting the highest speed at which it can push air aside...around 105 mph. That gear doesn't provide much torque multiplication on the low end, but who needs it? The bike already does 0-60 in 3.3 seconds.
That's why I think this conversation is important. If it was a motor of a variety which has lower torque at 0 rpm than at higher speeds, a single gear might not work very well -- gearing for top speed might leave a pretty big hole at low speeds. My point is that I don't think that's what's happening. I think Zero actually had to REDUCE the torque available at very low speeds in software, to avoid snapping belts, shredding rear tires and getting newbie riders into serious trouble.
-
I can add some explanation from Richard320 observation.
On my 2012 S I have recently installed the 2013 75-7 motor ( same as the 2013 S). the battery is still the original 66V and the controller is still the stock controller as the 2012 S and 2013 S have.... and same sprocket ratio
My previous acceleration with the ME0913 Motonergy motor was 7.8 sec.
With the new 75-7 motor it is now between 5 and 6 sec.
From my understanding the torque is related to the phase AMP available from the controller and the torque per amp of the motor. The 2012 and 2013 S have the same exact controller capable of 420Amp per phase so in this situation the only difference that can affect the torque is the motor. I clarely see that with 7.8sec to 5 sec drop ;)
On my previous stock 2012 S setting the torque curve is set at 66Nm max
On my new setting with the new 2013 motor it is set to 115Nm wich is not double but close too.
The 75-7 motor make a huge difference on torque but I lost a bit of max speed starting from 90km/h and up wich translate by reduction of the powerband. The field weakening feature of teh controller wich boost the max speed of the motor is enable but reduce efficiency too so I can not go as fast as with my stock 2012 motor was.
I also agree that the torque curve of the 2013 S is damped at low speed. On my modified 2012 S with 2013 motor I have maxed all torque from 0 to 4000rpm to 115Nm and it make also a great difference. The low speed acceleration is more brutal than before.
With the Size 6 controller I should get about 180Nm torque according to the 55% more phase current available.... all that on a 2012 S =))))
I expect to get the 0-100kmh in less than 5 sec with the weight of a ZF9 battery wich is about 50 pounds heavier than a ZF6.
Doc
-
That's why I think this conversation is important. If it was a motor of a variety which has lower torque at 0 rpm than at higher speeds, a single gear might not work very well -- gearing for top speed might leave a pretty big hole at low speeds. My point is that I don't think that's what's happening. I think Zero actually had to REDUCE the torque available at very low speeds in software, to avoid snapping belts, shredding rear tires and getting newbie riders into serious trouble.
I'd love to know for sure. I can say, from personal experience, I have a friend with a bike running the AC20 and a big RC lipo pack. He has it geared for around 100+, and it pulls just like the ZeroSR I rode a month or so ago. I know he's not done any de-tuning, and once you're rolling at around 20mph it's all hell breaking loose.
(edit: Just cross-posted with the good Dr., and I'll take that for what I was looking for. Thank you sir!)
-
My previous acceleration with the ME0913 Motonergy motor was 7.8 sec.
With the new 75-7 motor it is now between 5 and 6 sec.
It definitely sounds like there's a pretty big difference in the motors. Probably the main reason Zero designed their own -- they recognized there were big gains to be made.
On my modified 2012 S with 2013 motor I have maxed all torque from 0 to 4000rpm to 115Nm and it make also a great difference. The low speed acceleration is more brutal than before.
THIS! How did you do that? I'm assuming you need some sort of programming device to communicate with the controller? I'm an EE so I should be able to figure it out if you'd outline the process for me.
It's not that I WANT to snap drive belts, shred rear tires or even point the front wheel at the sky, but it'd be nice to have the ability if I do decide I want to! ;-)