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[evtricity]

Is it pretty solid? How much does the fairing shake around when you go over bumps?

Is the tank metal?  Do you have a power tank battery under there? Do you know how much the bike weighs the way you have it configured?

Yes, the fairing is very solid with minimal vibration. It also attaches onto some RG Racing frame sliders on each side as well as along the bottom of the frame on each side of the battery. I have a GoPro fitted on the U bracket and through the screen and it produces pretty smooth video. Videos at https://www.youtube.com/channel/UCtxWXT36o2YDEeQgO7V0saQ

Tank is a fibreglass CBR10000RR 2008 model. No powertank or onboard charging - I use 2 x 2kW TC chargers offboard via fast charge port.

The bike weighs 175kg in race setup and can be switched back to run on the road in 90 minutes (stock headlight, stock tail section, mirrors etc).

[grmarks]

The SR is a great bike, but how are you going to get a 50kw motor to keep up with the 120+kw motor in the bike Dr. Chris built and the others? 

[evtricity]

You're not on a fast circuit. But Chris' Voltron Evo still hasn't beaten the lap record for a Ninja 300 at some tracks in Australia so horsepower isn't everything. For me the Zero SR is a way to learn racing. I'm planning on moving to a much more competitive bike in 2016 and 2017 and getting a fast rider onboard.

Electric bike racing will always be small if people have to build their own bikes like the three bikes that blow me away at every race in Australia.

However, the Zero SR was the fastest production electric available in Australia in 2014 (and 2015) so I bought one and took the opportunity to see how it measures up on the track. I really hope that Zero's form the basis of an introductory or junior racing class like the Ninja 300s in the next 5-10 years. However the main game now is to beat the gas bikes and with a much more powerful production bike available in Australia next year that will happen in earnest in 2016 and 2017.

[evtricity]

A quick follow up to a question about overheating on my 2014 SR on the track.

I did a ride day at Sydney Motorsport Park (GP Circuit) yesterday (ambient temp 20-26C and mostly cloudy) and max bike temps were as follows:

Battery pack = 54'C - I shorten the sessions to keep battery temp below 55-56'C where I have had the bike cut-off previously
Controller = 64'C - note the Sevcon spec says it derates at 80'C and restricts time at high power output between 25'C and 80'C
Motor = 136'C - noticeable thermal cutback starts around 120'C (after 4-5 minutes on the track)

Battery temperature increase/decrease rates are as follows (approximate):
When on track - pack temp increases 0.8-1.2'C per minute (rate of increase is greater at lower battery temps)
When off track - pack temp decreases 1-3'C per hour   (rate of decrease is greater at higher battery temps)

So with a starting pack temp of 25'C and 2 x 15 minute sessions with a 45 minute break in between, the pack would be very close (25'C + 2 x 15'C - 2'C = 53'C) to the 55'C limits (charging etc).

Average speed on this track for me is just shy of 120kph including 60kph corners and 180kph straight.

I did a track day the previous week on the South Circuit at SMSP which is shorter and twistier with average speed about 95kph. Battery temperature increase was only 0.6'C per minute.

No doubt the IPM motor design will help with motor overheating but it's worth noting that battery pack design also limits performance on track days. The controller's thermal limits are not being reached and do not seem to be restricting performance (there is a motor torque cutback map in the controller that does that).

So what does this all mean?
For those who wish to take their Zero on the track - go for it but take your phone and keep an eye on the battery temp after each session.

[MrDude_1]

does it cool any faster if you spray the battery case down with water? or is all the heat "stuck" inside the pack, with no easy thermal path out of there?

[evtricity]

does it cool any faster if you spray the battery case down with water? or is all the heat "stuck" inside the pack, with no easy thermal path out of there?

Given the mass and density of the battery I doubt that cooling the case with water, ice or air will really do much i.e. cool the outer cells only and then just a little.

If you removed the plastic (or in my case fibreglass) tank and have some ice sitting on top of the case that would help a little but to be effective I'd need to get the heat pushed out of the battery box either through ventilating the battery box or with liquid cooling. I'm not keen to open the battery box up to do this but the limit on track time of the battery overheating is getting frustrating. Perhaps if I was running the smaller battery pack (e.g. an 8.5kWh on the 2014s) where there is only 3 of a possible 4 modules inside the case there would be room for ventilating fans and at least 2 of the 3 bricks would have an exposed side to try and cool.

Blowing air on from the outside it is easy to do and I do that to a small degree i.e. I run a fan between motor and battery pack to reduce heat transfer from the motor. I also have run ducting and recently an EDF into the motor itself which helps cool the motor both on and off the track.

That reminds me that I should do some side by side comparisons to compare the cooling benefit of the ventilated motor with the EDF on versus off, both on and off the track and post the results.

[MrDude_1]

My crazy head has me thinking about flooding the case with mineral oil to get the heat out.... lol
Flooded cooled battery.

[mrwilsn]

Perhaps if I was running the smaller battery pack (e.g. an 8.5kWh on the 2014s) where there is only 3 of a possible 4 modules inside the case there would be room for ventilating fans and at least 2 of the 3 bricks would have an exposed side to try and cool.

I would expect this to have a negative over all affect on battery over heating even though you would be adding ventilation.  When the controller draws current, each brick has to provide less current if you have 4 batteries instead of 3.  Battery temperature is largely driven by discharge rate and the discharge rate per brick will be higher with 3 batteries than with 4.  In fact, adding a power tank should allow longer rides before over heating because you have added a 5th brick so the discharge rate per brick is reduced even more.

For example, if the controller is trying to pull 400 amps and you have 3 bricks then each brick needs to provide 133 amps.  If you have 4 bricks each brick only needs to provide 100 amps and if you add a 5th brick then each brick only needs to provide 80 amps.

Of course, adding a power tank means additional weight and a higher CG.

[mrwilsn]

Also, do you use regen when racing?  Regen adds a lot of heat to the motor and the batteries.  Setting regen to zero for neutral throttle and braking should help with heat.

[evtricity]

Regen is turned off on the faster tracks but I sometimes run it on the slower tracks.

I appreciate that the smaller pack would mean more current and greater heat while riding so it's not really an option on the 2014 unless I want to cut the power down with the net result  being I'd go slower on a lighter bike!!!

However, I think it may be a valid option with the 2016 9.8kWh battery pack and their 29A cells and 10C peak discharge rate. Perhaps the 2016 SR's 13.0kWh battery pack is slightly less prone to overheating due to its greater capacity but I'm not aware of anyone taking one to the track yet.

Since the SR motor appears to have reached it development limit for performance and I don't need the range of an 11.4kWh battery pack for the track, reducing weight via a smaller pack seemed a reasonable option to improve performance.

Guess I'm a couple years early on expecting sports bike like performance from a Zero SR despite all my efforts to try and make it so.

[mrwilsn]

Have you tried different fairings?  I know you mounted a sport fairing but have you tried to really get the coefficient of drag down?

If you can reduce the coefficient of drag the motor won't need as much juice and the batteries won't get as hot.

[evtricity]

Have you tried different fairings?  I know you mounted a sport fairing but have you tried to really get the coefficient of drag down?

If you can reduce the coefficient of drag the motor won't need as much juice and the batteries won't get as hot.

No, haven't tried different fairings - it was a relatively expensive and time consuming exercise getting the RSV4 ones, customising them to fit the Zero and then painting.

I'm not sure how you can tell the CD of a bike/fairing unless you take it a wind tunnel!

I appreciate the aero benefits of the Vetter-style fairings but they're ugly as so that's not really an option. I'm trying to get respect for electric bikes at the track so trying to have the bike still look sharp is important.

Thanks for the suggestions though, feeling a bit down today about the SR. Probably didn't help I was on track with some of Australia's leading racers on Monday on Supersport and Superbikes on a track best suited to high power bikes. Perhaps moving to an LS218 will be the best way forward to showcase electric bikes on the track.

[mrwilsn]

Yeah, I think you would have to go to a wind tunnel to know the exact numbers but I really just meant trying to improve on aero.

For example, if you fill in the area where the radiator would be on an ICE you can improve aero.  In the pictures I was looking at it looked you just left that area open allowing air to hit the monolith.  If you fill as much of that area as possible while still leaving room for the forks to move you will improve aero.  Making a panel that covers that area with somewhat of a bubble shape will help without sacrificing looks.  You could also consider a larger front fender that improves aero.  That would also have a minimal degradation in cool factor.

Someone posted this pic on another thread....a front fender like this one would still look good.

[protomech]

You can experimentally determine drag and rolling resistance.

http://m.instructables.com/id/Measure-the-drag-coefficient-of-your-car/

[mrwilsn]

You can experimentally determine drag and rolling resistance.

http://m.instructables.com/id/Measure-the-drag-coefficient-of-your-car/

Interesting read. My take away was don't bother to actually calculate Cd. Just measure the time it takes to coast from speed A to Speed B then repeat after making the mod and compare the results.

If you want to compare performance of a vehicle before and after making mods, the change in coast down time itself is MUCH more meaningful than any change in Cd or Crr extracted from the coast down data.

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