Voltron-Evo; jonescg's new electric race bike

Post up a thread for your EV. Progress pics, description and assorted alliteration
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Post by offgridQLD »

"When I let my clutch out I have reciprocating mass to help carry me off the line with an EV you may have peak torque but you don't have anything previously spinning.

This is both good and bad, good from the standpoint that don't have mass to invoke wheelies or wheel spin, but bad that you don't have mass to help move it initially off the line.

Perhaps because you don't have that reciprocating mass you could launch with more controller power for a faster ET."


This is something that I think is often overlooked when people get to hung up on the EV (Max torque from 0-RPM) spec that get thrown around a lot.

I tend to find it's impressive when displaying it through in gear acceleration of a EV vs off the line or even 60 foot times.

Off the line it takes a lot of Torque to match that savage rotating mass of a flywheel and crank spinning at 10,000rpm+ and saying hello to the clutch in a real hurry. So max torque at 0 rpm sounds great and all.

10,000rpm of rotating inertia being released suddenly is savage.

One of my favorite examples of how savage it can be off the line (watch his left foot on the clutch)Image https://www.youtube.com/watch?v=qAo95Z7MPpw

Try driving a nail into some hardwood by pushing down on it with a hammer.You would need a hell of a lot of weight to force it in. Then swing the hammer at it. Inertia is a wonderful thing when used to your advantage.

Though I think on a bike trying to keep things smooth and controlled the EV should have a big advantage in controlling how the power is delivered at all times helps for a smooth controlled run with power to the ground vs wheel spin.

Kurt


Last edited by offgridQLD on Mon, 01 Feb 2016, 17:21, edited 1 time in total.
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Post by EV2Go »

offgridQLD wrote: One of my favorite examples of how savage it can be off the line (watch his left foot on the clutch)Image https://www.youtube.com/watch?v=qAo95Z7MPpw


If that thing had tits before hand, it doesn't now! The were definitely revved off.
offgridQLD wrote: Though I think on a bike trying to keep things smooth and controlled the EV should have a big advantage in controlling how the power is delivered at all times helps for a smooth controlled run with power to the ground vs wheel spin.
Exactly, while that big clutch dump helps get thing moving it also immediately put you into let's spin the wheels territory that is not good for consistent racing.

Also no big dump means you can turn the controller up more since there is no shock loading on the components, and they will last a lot longer.
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Voltron-Evo; jonescg's new electric race bike

Post by mikedufty »

There have been some interesting discussions in electric trials motorcycles forums on the merits of clutches. Some people considering installing a clutch to get that jump. I think some of the production models have a virtual clutch similar to the lock out button suggested above, it just allows you to go instantly to full throttle.

I always wonder how much of the soft take off in the i-MiEV is programmed in. My oset kids electric trials bike has a pretty savage response (in so far as 600w can be) I guess it is pretty low geared though.

The zero ds has a pretty soft takeoff too compared to an ICE bike with a clutch, but looking at videos of unintentional wheelies on their lower powered FX trail bike you wonder again if they've done that deliberately on the road bike to reduce wheelies, or is it just taller gearing?

Personally I like having to be careful not to wheelie.
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Post by offgridQLD »

"always wonder how much of the soft take off in the i-MiEV is programmed in."

I would say most of it. If you look at the power meter on the dash or through the OBD port and canion. You can see if you nail it from a stop or slow speed the power is limited as the needle swings to the right so slowly. If it was just due to tall single speed gearing and not soft starti the controller then the power meter would still peg to the right and it would turn to heat vs motion.

It's one hell of a fairy floss soft start they came up with on the Imiev.

Interesting outcome regarding the clutchless lectric trials bikes.

Kurt
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Post by T1 Terry »

offgridQLD wrote: "When I let my clutch out I have reciprocating mass to help carry me off the line with an EV you may have peak torque but you don't have anything previously spinning.

This is both good and bad, good from the standpoint that don't have mass to invoke wheelies or wheel spin, but bad that you don't have mass to help move it initially off the line.

Perhaps because you don't have that reciprocating mass you could launch with more controller power for a faster ET."


This is something that I think is often overlooked when people get to hung up on the EV (Max torque from 0-RPM) spec that get thrown around a lot.

I tend to find it's impressive when displaying it through in gear acceleration of a EV vs off the line or even 60 foot times.

Off the line it takes a lot of Torque to match that savage rotating mass of a flywheel and crank spinning at 10,000rpm+ and saying hello to the clutch in a real hurry. So max torque at 0 rpm sounds great and all.

10,000rpm of rotating inertia being released suddenly is savage.

One of my favorite examples of how savage it can be off the line (watch his left foot on the clutch)Image https://www.youtube.com/watch?v=qAo95Z7MPpw

Try driving a nail into some hardwood by pushing down on it with a hammer.You would need a hell of a lot of weight to force it in. Then swing the hammer at it. Inertia is a wonderful thing when used to your advantage.

Though I think on a bike trying to keep things smooth and controlled the EV should have a big advantage in controlling how the power is delivered at all times helps for a smooth controlled run with power to the ground vs wheel spin.

Kurt


The clutch dump is only of value in low torque engines, high torque engines actually use a slipper clutch to dump power off the line in an attempt to maintain traction. It is a whole science of reading the track to determine just how much clutch to apply to keep the vehicle accelerating in a straight line, even slight wheel spin means a trip into the fence. the Prostock cars are a great example of this but the biggest of them all is the nitro rails and funny cars, that clutch doesn't take up till half track sometimes. Being able to program in that reduced torque would make track tuning a science of the future, the driver does not have that option of how far to plant the foot yet still remain consistent. I guess as far as dial your own racing the ET could actually be tuned into the controller, that would take a lot of the driver and team judgement out of the sport effectively wrecking a great class of racing... something to be sorted in the near future I guess.

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Post by Adverse Effects »

you could even go to the extent of having a light censer that will launch it when your light go's green lol
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Post by EV2Go »

Adverse Effects wrote: you could even go to the extent of having a light censer that will launch it when your light go's green lol
No most classes of racing prohibit that. Electronics crept into drag racing years ago with a thing called a delay box. https://en.wikipedia.org/wiki/Delay_box which started all sorts of new rules to be made (I remember doing grudge nights in my Monaro around that time) basically it caused a big stink and people even in lowly street bracket racing categories got accused of cheating, and then people started hiding them to avoid detection.

Basically it got ugly and a ban was put on them at Willowbank, I don't know if it exists today.
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Post by T1 Terry »

Adverse Effects wrote: you could even go to the extent of having a light censer that will launch it when your light go's green lol

You want to be leaving the line as the power goes to the green light, far too late once the light turns green, he who snoozes looses Image
No idea how they would determine if there was anything improper in the way a controller was programmed, I'm guessing there will be some noses out of joint once the big noise boys start getting flogged when they elect to go heads up racing in the finals    Image

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Post by EV2Go »

Electric racing will be more consistent even without timing aids, by virtue of what it is. You are in the digital domain to start with.

Then you have the added benefit of no clutches or torque converters to content with, no having to make sure the revs are the same every time.

We are at an advantage to begin with, no rpms and maximum traction, virtually same conditions for every race.
Last edited by EV2Go on Wed, 03 Feb 2016, 07:46, edited 1 time in total.
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Post by bga »

With respect to I-Miev slow initial acceleration.

I suspect that all of it's programmed.

Makes sense to prevent parking lot collisions, but is a trap for the unwary on the road. I put this down to Mitsubishi being too cheap to install proximity (parking) sensors that could have triggered this behaviour.
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Post by jonescg »

https://m.youtube.com/watch?v=qUlt_2Z1ubc
think this might be the best onboard video of Voltron I've ever uploaded!

Keep an eye out for Taz's massive wheelie down the start finish straight on lap one :mrgreen:

New lap record of 1:15.481 at Queensland Raceway and for the first time ever, we were allowed to race in a national series with gas bikes. We only did 4 laps while the gassers did 8, but the potential is clear.

Also, check out the live feed of the race here: http://livestream.com/itvl/events/6376399 and skip ahead to 4:17:00 for the race.


On the top screen skip to 4:17:00 for race 5 (same as the onboard footage).

She's pretty close to the limit with the current setup, so next step is to add a steering dampener and eventually put some decent fork internals in there. We'll sit out 2017 so we can develop a bigger battery capacity yet still have the same mass as currently there- 212 kg.

Well done Taz, impressive stuff.
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Post by jonescg »

And on the supject of clutches, the 6 race starts we did were all pretty good for us without one :)
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Post by weber »

Great stuff! Thanks Doctor Jones.
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Post by evric »

Congratulations Chris and Taz.
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Post by Sutho »

Nice one Chris!
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Post by jonescg »

Sutho wrote: Nice one Chris!

Thought it might've reminded you of the Radical's start - see ya later, I'm up front Image
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Post by jonescg »



Last race of the season.
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Re: Voltron-Evo; jonescg's new electric race bike

Post by jonescg »

Been a while since I posted in this thread!

I've been getting the band back together ahead of the EV Expo in Perth (November 3rd-5th 2023) and that means building a new battery. The LiPo pouch cells in the 6 kWh battery were raced pretty hard, so they were destined for a tank of sulphuric acid.

The new battery will be built using Molicell 21700 cells; 4 Ah each, 5 in parallel and 168 in series. So that's 840 cells all up, roughly 12 kWh. They are a fairly energy dense cell which means the pack will only weigh about 10 kg more than the original 6 kWh battery, yet pack twice the capacity!
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Here's the downside - the DCIR of the LiPo pouch cells was measured in micro-ohms. These cylindrical cells are in the realm of 16 milli-ohms. So if I wanted to approach the same power as the pouch cells, I'd be producing over 30 kW of heat!!! The termination approach is crucial. 0.15 mm x 8 mm nickel tabs are incandescent at more than 30 amps, and I'm hoping to pull the occasional 50 amp burst, so I discovered backing it up with 0.07 mm copper foil works, and it's still able to be welded to the cell. It's a pest to prepare, but the system works. The alternative is a $35,000 pulse arc welder which can fuse copper tabs to the cell tops...


https://youtu.be/YE09SYRnjrw?si=xICHqqfsxH0Q0XNB

SO far the copper busplates are 3/4 done and the capture plates are being machined this week.
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I'll be making four modules of 42s5p and terminating them at one end using brass nuts soldered to the underside of the copper:
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Meanwhile, I've been working on the rear wheel. Ever since we got the new swingarm we never really noticed that it felt better in left hand turns than rights. Only when we were most of the way through the season did we realise the rear wheel was offset about 12 mm from the front wheel - it was sort of crabbing! So I set about shuffling the wheel to the left, while keeping the brake disc and chain roughly were they were. Not easy, but a 12 mm spacer on the disc and some after-marked titanium bolts addressed that problem, while a new spacer on the right made sure the wheel bearing was supported.
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On the chain side, there was a good 8 mm of clearance with the tyre, so that had to come over to the right. That meant an offset (or should that rad, inset) sprocket and pushing the drive sprocket a bit further out. Not completely comfortable with putting such a large moment on the drive sprocket, but it is 44 mm diameter steel.
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All up it's looking good, and now, actually, in alignment!
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Post by weber »

Great to see this thread resurrected. :) Good onya, Chris.
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Post by jonescg »

Something I'd like to know is if I can get a half-way decent coulomb counter for the race bike. I see Altronics sells one of these:
https://www.altronics.com.au/p/q0596-fl ... ith-shunt/
But it's powered from the voltage source, which maxes out at 120 V DC.
I thought about supplying it with a voltage divider output, but these are particularly wasteful. Any options?
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Post by weber »

jonescg wrote: Tue, 05 Sep 2023, 22:21 Something I'd like to know is if I can get a half-way decent coulomb counter for the race bike. I see Altronics sells one of these:
https://www.altronics.com.au/p/q0596-fl ... ith-shunt/
But it's powered from the voltage source, which maxes out at 120 V DC.
I thought about supplying it with a voltage divider output, but these are particularly wasteful. Any options?
I don't think there's any way you could safely use that unit with your 750 V battery, no matter how you power it. The problem being that the whole unit and its cable will be operating at the potential of one side of your traction battery. You want that traction battery to remain floating relative to the chassis so that a single touch is not lethal. But the display unit and its cable are unlikely to be insulated for 750 V.

You need a coulomb counter where the differential amplifier and microcontroller are attached to the shunt, safely enclosed in a box with your contactors, and only communicating with the display by opto-isolated comms. And powered from the 12 V battery via a miniature isolated DC-DC converter. With 6 mm of creepage/clearance between traction-battery-referenced and chassis-referenced zones on the PCB. Like this "IMU" we built for the MX-5. Explanation: viewtopic.php?p=48111#p48111. Later version: viewtopic.php?p=48473#p48473.

The "display unit" in our case is the MX-5's existing fuel gauge, driven by the Tritium Driver Controls unit (DCU). So the IMU just communicates the state of charge to the DCU. So not directly usable in your case, but could be adapted. I hope you can find an off-the-shelf unit that is isolated at the shunt.
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Re: Voltron-Evo; jonescg's new electric race bike

Post by antiscab »

I think I have a shunt unit with wireless comms to the display unit floating around somewhere. Brendon put me onto it when I was looking at his (now sold) Sirion
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Post by jonescg »

I can use the existing voltmeter and ammeter on the dash, as these are 12 V units powered by isolated DCDC converters. The voltage is sensed through a high impedance voltage divider inside the battery, while the current shunt allows for voltage drops to be interpreted as amps. But there has to be a more elegant option for higher voltage systems, surely?
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Post by weber »

If you're thinking of hall-effect current measurement devices (typically LEM brand), similar to a clamp-meter, they are useless for coulomb counting as they have terrible offset errors and terrible drift in that offset. You need an accurate zero for coulomb counting, otherwise it will soon integrate its way to zero or 100% when the bike is sitting doing nothing. A shunt is still the best way. And since nothing is perfect, a coulomb counter needs a way to detect full charge and reset itself to 100% (e.g. by reading the battery voltage). So normally you want a single unit that measures voltage and current and integrates amp-hours (or coulombs) and calculates SoC.

And I don't know of a better way to measure high voltages than a voltage divider where the high side consists of a string of resistors in series.
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Re: Voltron-Evo; jonescg's new electric race bike

Post by jonescg »

Seems there's a market for such a product. Provided the voltage divider is internal to the battery for voltage sensing, and the device is powered by an isolated DC/DC, how hard could it be?
Most of the cheaper products on the market are powered by the very same voltage it's sensing. I can't see why this shouldn't be from some isolated source.
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