I’ve looked at those darn Agni graphs explaining the same thing to everyone….. No one ever understands what they’re actually looking at…..

For the last graph at 72V, Those graphs are ONLY 4800 to 5200RPM, its only relevant for that RPM range, it is not a normal torque curve and its VERY misleading. You are correct, if you keep the motor at ~5krpm, its very efficient, anywhere else though, and its less efficient. You’re going to be running this motor from 0rpm up to 6krpm, and the efficiency will NOT be at its peak over that entire range. That is only a PORTION of the RPM range. Look at a different torque curve that goes across the whole RPM range…. you’ll see what I mean:
http://www.evfr.net/synkromotive/components/motors/K91.pdf

Headway are not really low current, they’re just not A123 or Kokam…. they’re very good power batteries. 100A out of a 10Ah battery ain’t bad. 600A out of a 6p setup. 300A continous.

I don’t think you’ll be able to beat ICE bikes, mostly because the motors going in aren’t powerful enough to sustain race speeds that the ICE’s will, nor do they have the RPM range to have good low end, and good top end without a transmission. You need more than 17hp continuous/motor to get above 120mph with acceptable acceleration. If you’re fine with breaking 100mph, then yes, they’ll work just fine. Its not the battery energy I’m concerned with (Throw kokam in there and you’re done), I’m more concerned with continuous power of the motors.

If you look to the agni graphs you will see that the range of top efficiency is very wide:
http://agnimotors.com/95_Series_Performance_Graphs.pdf

It is not like driving a combustion engine ;-) Over 25% load there is nearly no difference in efficiency.

I know that there are more cells available, this was just a explanaition for the three different types (high and low current LiFePo4 and Li-Ion) which can be used in a eletric racing bike.

85% is a bit liberal, I know. But here you see that if you need around 12kWh to beat SSP bikes your battery has to be larger then 12kWh/0,78=15,4kWh

Such a battery has a minimum weight of 123kg! (Kokam)

@skadamo
I was thinking about a front generator too, but I decided that it is impossible to use a hubmotor in a racing bike.

In a SSP or Superbike you need at least a motor like a agni to recover enough energy to safe some cells…

11,7kg unsprung and rotation mass, haha ;-)

Go on!

The pictures of the SWIGZ bike are from the original press intro of the bike which was a few months ago. In this time it is possible that Chip’s team added front wheel regen. I could ask him but he did not want to give up too many tech details at this time….

You forgot that the transmission can put the motor in its most efficient RPM range, negating any losses you might see by a single speed. The more in its efficient range that a motor is, the less likely you are to see much difference in efficiency between the two.

At the moment, there are a lot more cell types than those. Headway more of a medium current cell, Thundersky and Hipower are low current cells, but large format. Kokam is WAY more dense than A123, but their C-ratings aren’t as high as some other batteries (5C cont, 8C peak). Others: PSI, BMI, Lifebatt, Turnigy, Valence, Thundersky, Sky energy, Hipower, PHET, K2, DLG, Sony, Panasonic…..

I don’t think you’ll see that much overall efficiency drop due to the extra weight and friction, see above comment. If you run the motor in its efficiency band (whatever RPM that might be for the motor), you actually have a higher efficiency than running that motor with a single gear at a higher RPM outside its Efficiency band…..

As far as electrical drivetrain efficiency, I think your calculations are a little off. Agni motor efficiencies are 93% peak. Thats also not at peak RPM. Your controller efficiency is what, 95%? Battery chemical—> electrical efficiency is about 95% or higher, mechanical efficiency is no higher than 95%, add another 1-2% loss for electrical connections/other current draw (contactor/dc-dc/gauges)/various mechanical loss…. total below 78% ASSUMING you ONLY run the motor in its most efficient range. I know you’ll see way below this in the end.

You can only calculate so much on paper….

you forgot that a two speed gearbox with clutch (for quick gear change) with housing is at least 5kg weight extra, then you loose around 3-5% for friction

FIM E-Power courses are flat and very smooth, no stop and go courses like calafat where I did my first test.

At the moment there are three different typ of cells available:
1) (high current LiFePo4) A123
2) (low current LiFePo4) Headway
3) (Li-Ion) Kokam

If you loose 5% for friction you need 5% more batteries, 80kg*5%=4kg.

A123 and Headway have nearly the same wh/kg ratio, kokam is a bit better

Don`t forget, on race tracks you loose a lot of energy while braking and accelarating all the time, on IOM you go a long time with the same speed, I guess that the required the capacity is nearly the same.

If Chip likes to go as fast as a supersport bike he will need two front brake discs, because topspeeds have to be the same…

A 600 burns at least 6.5l fuel for 40km, each liter has a around 9kWh -> 6,5l*9,5kWh/l=61,75kWh.
Efficiency is around 20% = 12kWh for 40km

The complete e-drive has a total efficiency of ~ 85% 12kWh/0,85=14,11kWh.
Agni used a 10,7kWh battery for the IOM.

I will use a 4 or 5kWh battery with headway cells with a weight of 45 or 56kg.
With the kokam cells you can save around 15%.

10 weeks to go…

I think the bikes that we see in 2010 will be pretty fast and definately go the 25 miles. TTXGP at IOM was a little long for the first year, but with the batteries that some of the teams are using, I have no doubt that 25 miles at race speeds will be achieved.

The good thing about a 2-speed, it may not need more energy, but it will allow the motor to sit at a happier torque/power band to allow for brisk acceleration without drawing tons of current. I think energy will be SAVED by using a 2-speed.

While closing the throttle the motor will work like a generator.

As I see they have no generator in the front rim. I guess the recoverd energy is less than 5%, because while hard braking the rear wheel gets very light.

If you adjust the controller to recover more engery the rear wheel is stopping by now.

It is like driving a supermono or a ducati without slipperclutch.

In street mode without hard braking you can regenerate a lot of kinitec energy, thats correct.

Some words to the lap times:
Ohms laws will work on e-bikes too, for quick accelaration you need a lot of power, and power is known as Voltage*Current

If you have a two speed gearbox you need a lot more energy.

I guess, without the new lithium air cells every race bike will be as slow as a 125 street bike on a distance of 40km.
Maybe for one or two laps with high current cells you can go a bit faster…

Let`s go!