Electric Vehicles

[Luckypants]

I agree with Bibs, having some speed restrictions built in to the vehicle are useful. My car has a cruise control that uses gps and sign recognition to set the max cruise to the limit. Helpful in all situations but very much so on motorway roadworks or long wide roads with a low limit. It needs switching on, so I choose to use it or not. It does not restrict my speed without my say so. I can also flip that to speed limiter, so I drive the car but it will never go above the posted limit - I don't use it but see times it would be useful.

[SV650rules]

Originally Posted by Bibio

i like the idea of automatically restricting speed in cities, towns and villages. oohh and the speed wont be set by signs it will be via GPS. my car already has a button to restrict the speed and has settings for 20, 30, etc.etc. do i use it? only in big cities where they keep changing the goal posts. having said that i think i might be getting a nip through the door as i passed a scamera van at 35 in Edin as it was on a hill and the speed restrictor dont work too well on hills.

GPS accuracy is good most of the time - about 5 metres, but is only as accurate as the map data it is referencing, and how many people driving around with maps years out of date, and GPS only works when speed limits haven't been changed for a while ( new map releases don't update all the data at once for every speed limit in the world ) - it would be better to have transponders in speed limit signs that pings information to the vehicle - but that will cost money, but same problem exists as with the camera systems now being used that speed limits on side roads get picked up by mistake. So maybe short range chips embedded in road surface.

[Ruffy]

Originally Posted by svenrico

Well , there is more than just the sound that gives a motorcycle engine character. Different types of engine, triples, V twins, 4 cylinder etc , all have different characters. I thought all motorcyclists understood that !

Originally Posted by svenrico

I didn't say that a rider only rides a bike with one particular type of engine! I've ridden singles, twins, triples, 4 cylinder as a lot of people will have.
What is happening though is that the only choice will be an electric motor.

I don't think electric drive train needs to be a bland or boring drive train. Far from it. As I said before, I conceive of a day when the sales/marketing teams start demanding different 'feel' out of the machines to meet the customers' demands. The motor drive electronics can be engineered to deliver that (not dissimilar concept to fuel/air mapping of ICE injections systems).

Originally Posted by Ruffy

If by "character" you mean feel rather than noise, then that character could be programmed in to the drive system - drive electronics can be made to give pretty much whichever torque curve you want to have (within the motor's overall core capability).

So following on from that, just imagine having a single bike where you could flip the motor type by pressing a button! Damn sight easier than creating a 'special' by an engine transplant. Ok riding position and geometry differences might still need dealing with but why do we keep getting stuck with the mindset that an electric motor drive is really just a tedious fake or sub-standard drivetrain arrangement?

[Seeker]

and if you want more character, take off the wheel weights then you'll get your vibration. I like the idea of turbine like smoothness as the bike surges ahead with maybe a faint whine from the motor. The whine might be from my bank balance

[Luckypants]

I like the idea of an electric bike. Adjustable engine braking, instant throttle response, max torque from a standstill for easy hill starts. I would miss the engine sounds, especially blipping the throttle on downshifts which is part of the character argument I suppose.

But if the choice is no bikes or electric bikes - electric all the way.

[DarrenSV650S]

I've never understood why anyone thinks max torque at 0rpm is a good thing. That's the last place I'd want it. That's when you are most likely to break traction.

You've then got the disappointment of producing less and less power as you rev.

I think it makes more sense to have enough power down low for normal riding, then when you need it you thrash it to get the most power

[Luckypants]

Max torque is available at zero RPM, doesn't mean you have to use it. It means you don't have to rev like crazy and slip the clutch to get going on a hill, just smooth torque to get going.

Not sure what you mean by producing less and less power as you rev? An electric motor produces pretty much a flat torque curve, so its producing the same torque at 6000rpm as at 1rpm. With power being a function of torque and rotational speed, as you rev power increases. With an electric motor, you have power everywhere. Or is it me misunderstanding something?

[SV650rules]

Originally Posted by Luckypants

Max torque is available at zero RPM, doesn't mean you have to use it. It means you don't have to rev like crazy and slip the clutch to get going on a hill, just smooth torque to get going.

Not sure what you mean by producing less and less power as you rev? An electric motor produces pretty much a flat torque curve, so its producing the same torque at 6000rpm as at 1rpm. With power being a function of torque and rotational speed, as you rev power increases. With an electric motor, you have power everywhere. Or is it me misunderstanding something?

Electric vehicles don't need a clutch, unlike an ICE the motor does not need to keep turning while the vehicle is stationary.

An AC induction motor is used in most EV because it is simple and rugged and does not need brushes or slip rings to get power to rotor ( the DC from the battery is changed into multi-phase AC by an inverter ), an induction motor has max torque (breakaway torque ) at zero revs when there is maximum attraction between magnetic poles. As the speed increases then 'slip' occurs between the magnetic bits, as the motor approaches 'synchronous speed' ( as determined by the number of poles and the supply frequency ) the attraction between the poles lessens - An AC induction motor can never achieve synchronous speed because the torque has dropped to zero ( when the rotor catches up with rotating magnetic field produced by stator there is no attraction to pull the rotor around ) , but from standstill to max speed the torque curve continuously drops as a curve. With a DC motor the torque curve is linear from max at standstill to non at full speed. What an electric motor driven vehicle needs is a gearbox LOL, that will allow the torque to be maintained. Diesel electric trains used the big diesel to drive a generator to supply power to traction motors - the diesel would rev like crazy as the train was starting off to supply maximum current to the traction motors for breakaway power, once train moving the whole thing quietened down ( until a dreaded hill approached ).

There are some clever types of electric motor that use electronic switching of power to level the torque curve and increase the speed range ( switched reluctance motors ).

https://en.wikipedia.org/wiki/Switched_reluctance_motor

[DarrenSV650S]

Originally Posted by Luckypants

Max torque is available at zero RPM, doesn't mean you have to use it. It means you don't have to rev like crazy and slip the clutch to get going on a hill, just smooth torque to get going.

Not sure what you mean by producing less and less power as you rev? An electric motor produces pretty much a flat torque curve, so its producing the same torque at 6000rpm as at 1rpm. With power being a function of torque and rotational speed, as you rev power increases. With an electric motor, you have power everywhere. Or is it me misunderstanding something?

Most electric dyno graphs show power starting high then gradually decreasing with revs, and then it drops off a cliff at relatively low rpm compared to an ICE

[Ruffy]

Originally Posted by SV650rules

... an induction motor has max torque (breakaway torque) at zero revs ...

Erm, I'm not sure that's correct. I admit it's been a long time since I've been involved in such detail but I'm sure I recall that AC induction motors have much lower torque at startup that at peak (typically about 1/3rd to 1/2?)

If higher torque is required to deal with a high inertia load this is generally dealt with by electronic starters or drive controllers that vary the frequency of supply to control the start & ramp up to 'steady state' speed.