ElectricMotorcycleForum.com
Makes And Models => Zero Motorcycles Forum | 2013+ => Topic started by: Burton on September 30, 2014, 10:23:29 PM
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Two questions and an observation.
1) Does pack voltage affect 0-60 times?
2) If you program your bike via dongle then later open (note just open and adjust no settings here) the default zero app does the bike loose it's programming you set up via dongle?
When I got my bike from EC he said it was faster than the 2014 SR but I have done two 0-60 pulls with a limited pack voltage of around 99 and it took 6 seconds to get to 60 no matter what mode I was in.
Thoughts? I know people here don't typically get their bikes reprogrammed but I know some of you have.
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Torque is determined by the current limit so the voltage of the pack or the SOC does not matter.. .unless pack is really low and that the controller is in battery saving mode and reduce current to the motor.
Max speed is determined by the max rpm setting of the motor controller and the voltage of the pack.
The 0-60 time is a matter of POWER witch is both torque and speed.
At lower speed the max current setting of the controller matter the most. The top speed of the S and SR is about 100mph wich is way faster than the 60mph so the voltage of the pack should not matter unless the battery is too low and controller reduce power to protect it.
Doc
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Thanks for the reply. What is considered a low pack voltage?
Each time I had about 18% on the pack. I believe EC set the bike up to have no limp home mode since it was a race bike. I may have to charge the bike and do a 0-60 pull at full voltage to confirm this wasn't the issue. :/
I have asked EC to send me a dongle so I can confirm his settings are still in place since I do use the Zero app to get state of charge and miles ridden.
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The 0-60 time is a matter of POWER witch is both torque and speed.
Doc, I hate to try to disagree with you on anything, but I think that's wrong. Maximum speed/acceleration on any vehicle is subject to two constraints: Torque and horsepower. At low speeds, you're going to be torque-limited, at high speeds, horsepower-limited. That's why a Zero SR kicks so hard off the line (monumental torque) but has a top speed of "only" 102 mph (67 horsepower). The question is where does the crossover from torque-limited to horsepower-limited occur?
From my experience, on the SR it occurs somewhere in the 60-80 mph range; it's hard to be more specific because it's a very smooth transition. But I'm pretty sure you're strictly torque limited up to freeway speeds.
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That's why a Zero SR kicks so hard off the line (monumental torque) but has a top speed of "only" 102 mph (67 horsepower).
Isn't the SR just like the S in that it has a digital limiter on the speed limit? I know my 2013 with size 6 controller has no such limiter any more.
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Burton,
I think you should charge the pack to the maximum before doing the run.
Even though EC may have customised settings, the power/torque is significantly reduced below 30% battery level (at least on the Zero SR which has the size 6 controller too) and there may be something else restricting which the custom setting can't control.
David
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Isn't the SR just like the S in that it has a digital limiter on the speed limit? I know my 2013 with size 6 controller has no such limiter any more.
I believe you're right, Burton, but do you think they significantly undergeared the bike on purpose? It seems to me that a top speed of 102 is about right for a full-size bike with 67 horsepower. Hopefully they geared the bike to provide max horsepower at max road speed, and added the rev limiter to keep you from overspinning the motor going downhill and/or a with a strong tailwind. I can't believe the bike would be capable of 140 (or even 120) and they wouldn't try to at least get close to that capability.
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The 102mph limit of the SR is required because it's reaching maximum motor speed with the given gearing.
Lower the gearing and there will be a marginal improvement in 0-60 times (not much though as the motor torque seems restricted under 20mph) with significant loss in max speed. Like the Brammo before it, the 100mph figure may be more a marketing thing than what the bike is capable of.
Increase the gearing and the bike will do over 120mph but 0-60 times will be a second slower and overheating of the motor is more likely as it will be straining harder under any degree of acceleration.
My view is that the bike speeds are limited primarily by the motor overheating and the lack of fairing. Ninja 300s with fairings go faster with less horsepower and torque. Adding fairing to the SR would allow for better acceleration, top speed and less overheating. On a naked gas bike you don't see these issues until over 120mph and they are mostly evident in the lousy fuel economy achieved by such bikes on the track or during similar high speed riding.
Zero will have to move to a faired bike, bigger liquid-cooled motor, higher voltage battery pack or all of the above if they are able to move beyond the constraints of the SR. Don't get me wrong I think the SR is a great bike but the 116V pack, air cooling and lack of fairing means it can't comfortably go much over 120mph.
Like others on this forum I'm trying to address the latter two limitations. Hopefully the outcome will provide some good information to feedback to Zero, particularly around the benefits of running full sports bike fairing on a Zero SR. Can't be easy for the motor to push someone like me through the wind at 100mph!
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Then my vetter faring and ventilated motor will be interesting to play with as wel ;)
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Should do!
Has your motor been cut out on both sides or just the right side?
Seems a drastic thing to do and I'm baulking at cutting the motor face plates to be honest but I'm not sure there's any other effective cooling options. I was hoping they might incorporate some more mods in the 2015 bikes for what is the bikes Achilles heel for highway riding in summer or any form of racing.
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Has your motor been cut out on both sides or just the right side?
Well this was a former race bike so it has been modified for it. And yes it is cut out on both sides. (click images for bigger size)
(https://farm8.staticflickr.com/7442/13727074055_2881c65ce5.jpg) (https://flic.kr/p/mV1QSB)
(https://farm8.staticflickr.com/7021/13727068035_64c04e3ab1.jpg) (https://flic.kr/p/mV1P5P)
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Regarding top speed, my comment would be: If you are not racing why would you need a vehicle that goes faster than 100 mph? In most areas of the world riding at that speed will land you in jail and get your bike confiscated and your license suspended. 100 mph is plenty fast for me, but I do appreciate and use the mid-range roll-on performance of all electric motorcycles. :)
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Maximum speed/acceleration on any vehicle is subject to two constraints: Torque and horsepower. At low speeds, you're going to be torque-limited, at high speeds, horsepower-limited. That's why a Zero SR kicks so hard off the line (monumental torque) but has a top speed of "only" 102 mph (67 horsepower). The question is where does the crossover from torque-limited to horsepower-limited occur?
Well I agree also with your comment. maybe I misexplained myself due to language barrier.. lol
Top speed is related to power ( hp) and acceleration is relatd to torque & power... but don't forget power = torque * speed
That famous limit where the torque begin to drop is at about 4000rpm on the sevcon+75-7 motor if I remember. This is also where the field weakening ( timing advance) begin I think.
The max rpm the controller of the motor is set is at 6300rpm. As well the motor can go higher rpm if it would not be limited by the controller but problem with the motor would happen.
Doc
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Isn't Zero motors with permanent magnets? If it's the case, how can you weaken the field???
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Regarding top speed, my comment would be: If you are not racing why would you need a vehicle that goes faster than 100 mph? In most areas of the world riding at that speed will land you in jail and get your bike confiscated and your license suspended. 100 mph is plenty fast for me, but I do appreciate and use the mid-range roll-on performance of all electric motorcycles. :)
I completely agree. Especially if you're not wearing full gear. One little mishap at that speed and just the road rash alone could be life threatening.
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Isn't Zero motors with permanent magnets? If it's the case, how can you weaken the field???
The stator (coil-created) field begins to weaken when the drive frequency increases to the range where the inductive reactance becomes significant (on the order of the winding resistance). [I have no idea what frequency that is on a Zero motor... :]