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[CliC]

I thought it depended on speed. If the motor is turning slowly, the voltage provided to it by the controller is less than battery voltage, so motor amps can actually be greater than battery amps in that case (motor power output is still less than battery max power output). The motor-controller system acts like a buck converter in other words. This would also explain why the torque is the same at lower RPM with one per two packs, but max motor power is lower with one pack.

[trikester]

The controller controls current to the motor which determines how much torque is produced. In this case the controller is a switching regulator so each pulse would be full peak current but with a duty cycle determining the rms current (it's an AC motor). The rms current in the motor would be equal to the rms current flowing from the battery. It is physically impossible to have more current flowing in the motor than what is being supplied by the source (the battery). It is a series closed loop so the current all the way around the loop has to be equal.. Voltage drops at various points around the loop can vary greatly.

The question is: do they cut the max peak current to half with a single battery or do they cut the max rms current to half? Either way they control the max battery current. My guess would be that the peak is reduced to half, that would be the easiest to do in the controller. If full throttle is equal to a 100% duty cycle in the controller then the 1/2 setting of the peak would be 1/2 of the two battery full throttle (100% D) current.

Trikester

[NoiseBoy]

I thought it depended on speed. If the motor is turning slowly, the voltage provided to it by the controller is less than battery voltage, so motor amps can actually be greater than battery amps in that case (motor power output is still less than battery max power output). The motor-controller system acts like a buck converter in other words. This would also explain why the torque is the same at lower RPM with one per two packs, but max motor power is lower with one pack.

The Sevcon uses something similar to PWM modulation so the peak voltage is essentially always the same as the battery voltage.

[trikester]

Yes, you have peak voltage and rms voltage (or ave voltage) by PW modulation. Same with current.

Trikester

[emotofreak]

The amount of current you pull out of the battery (battery amps), is almost never the same as the amount of current being delivered to the motor (motor amps), this only occurs at true max power. Think of it this way. If you want 1kw of power, and you have a 100v battery, this means you only pull 10amps out of the battery. To supply this 1kw to the motor you must apply some amount of voltage, which is a ratio of RPM to voltage. For example, to spin the motor at 1/10th it's max RPM, you apply 1/10th max voltage, actually you need a bit more but this is close enough for approximation. This means to spin the motor at 1/10 max rpm, you apply approx 10 volts at 100amps, to get your 1kw of output. It also means, if your motor and controller are up to it, you could push 1000amps into your motor at 1v, while only pulling 10amps out of you 100v battery.

Hope this makes sense.

[trikester]

I repeat. It is a series closed loop. The current flowing in the battery cannot be different than the current flowing in the motor. It is a physical impossibility for there to be a different current flowing through the battery than through the motor. They are the same circuit including the Sevcon. The switching controller determines the rms or average current (dependent on which you want to measure) being pulled from the battery and delivered to the motor. That's why Doc's shunt, in series with the battery, can be used to calculate power, kWh, etc. It's because the current in any part of the loop is the same. The voltage across the motor depends on the rpm at any given moment.

When I roll on the throttle the current from the battery to the motor increases immediately, the voltage across the motor rises as the speed of the bike (motor rpm) increases more slowly. The current can be very high at first and then will drop off as the voltage climbs with increasing speed until a steady state is reached. That's why it takes more power to accelerate than to hold a steady speed. When I first twist the throttle the current has to go high to produce the power required to accelerate but at the voltage the motor was producing at the instant the throttle was increased. As the voltage increases with increasing speed the current can drop maintaining the required power. Current x Voltage. Voltage rises with speed and current drops as it does.

If the bike has two batteries in parallel then 1/2 the motor current is coming from one battery.

Trikester

[trikester]

I just figured out the problem here. You are thinking of the Sevcon as a switchmode voltage controller, it is not, it is a switchmode current controller. It is telling the motor to take a certain level of current and the voltage across the motor will rise or fall depending on that current and rpm. Of course power is the product of those two but it is current that the Sevcon controls, not voltage. So it is not like a step up or step down voltage regulator where the current from the battery could be different than the current in a restive load. Since it is current that is being controlled, then it has to be the same around the loop.

The Sevcon controls the current taken from the battery and passed through the motor. It doesn't sense the voltage across the motor which is determined by the motor's series resistance and the rpm at any point in time.

Trikester

[JohnSki]

"Yes, you have peak voltage and rms voltage (or ave voltage) by PW modulation. Same with current."

RMS and average voltage are not the same. A normal voltage meter reads average voltage (0.636 x Vp) and assumes that it is a sine wave at 60 Hz.  It is calibrated to display the RMS voltage (0.707 x Vp).  If this was not the case there would be no need for True RMS meters.

[Doctorbass]

A new model for 2014

Apparently called the Type-R.

It should be able to reach about 230km/h

I wonder if they will keep the S or replace with this model...

no more info from now... I leave you dreamig on the rest of teh specs

Doc

[NoiseBoy]

A new model for 2014

Apparently called the Type-R.

It should be able to reach about 230km/h

For about 5 miles before you have to pull over and recharge.  I would rather see better acceleration and a faster charger that makes use of the Sevcon to keep weight low.

[Doctorbass]

The Type R is apparently untue according to someone i know working at Zero

we will see...

[NoiseBoy]

Maybe it is the Hollywood Electrics bike with the size 6 that you have heard about?

[protomech]

Ted Rich's Zero S, now with a Size 6 controller, was pushing 120 mph / 190 kph on the straight at Indy with minimal fairing. I don't doubt a size 6 bike could push 230 kph on a longer straight with taller gearing and better aerodynamics.

[BrianTRice@gmail.com]

Ted Rich's Zero S, now with a Size 6 controller, was pushing 120 mph / 190 kph on the straight at Indy with minimal fairing. I don't doubt a size 6 bike could push 230 kph on a longer straight with taller gearing and better aerodynamics.

So, you're headed to Bonneville at some point, then?

[grindz145]

I'm going to speculate on a rear brake upgrade and some suspension tweaks.