The Mass-EV Virtual Showcase

Look at the technology under the hood,

including the

I created this so I can add the mechanisms and get an idea of the engineering dimensions myself.

It's important to make sure this doesn't have unrealistic properties,

like the motors sticking out of the sides or the batteries making the passenger space too small.

I will be adding some sketches of the mechanisms too.

The current design of chassis has 2 x 50kW motors, 104 x 45Ah lead-acid batteries and 14 SuperCap packs.

However this will be redesigned based on the figures experienced by drivers of the Toyota Rav4 EV.

This machine has a single 50kW motor and 27.5kWh NiMH battery.

The original 1996 prototype had 24 x 55Ah 12v VRLA (lead-acid) batteries (16kWh) weighed 1.5tons (3364lb).

It had a top speed of 78mph and a combine cycle range of 68.2miles.

Found by testing: at 45mph the Rav4 EV consumed 9kW, at 60mph it was 17kW and "combined" was 6kW average.

The 2006 Toyota RAV4 has a drag co-efficient of 0.31.

The power, speed and range figures were obtained from the US Dept of Energy's Advanced Vehicle Testing

This is the report on the 1996 Toyota Rav4 EV.

Below are performance graphs extrapolated from the US Dept of Energy data.

As you can see from the above graph,

the Rav4 EV would have a top speed of between 90mph and 100mph for a 50kW motor.

The actual value on graph is 92.5mph.

The top speed for the same car with 100kW motor(s) would be 118.5mph.

This graph shows the Rav4 EV would have a range of:

37 miles at 80mph,

45 miles at 70mph,

57 miles at 60mph,

72 miles at 50mph,

92 miles at 40mph,

100 miles at 36.5mph.

This is on a battery pack of 16kWh (24 x 12v/55Ah).

The Mass-EV being a smaller and more aerodynamic car would require less average power

but would need more instantaneous power due to it's greater weight.

The Mass-EV motors need to have a higher power rating to maximise regenerative braking.

So it's clear the Mass-EV would hit the design targets with only about 50 x 45Ah 12v batteries (27kWh).

This is the Data for the General Motors EV1 (Lead-Acid)

It has an electrically limited top speed of 112mph.

There is also a 50kW motor for the rear but this is only used for high acceleration or in poor traction.

The Lexus 400h has a curb weight 1.94tons and has a drag co-efficient of 0.35.

The Toyota Prius II has 80kW motor and will maintain 80mph using just this motor.

This was found out by practical experience using my wife's car.

The Mass-EV will be a similar size and aerodynamic shape to the Toyota Prius.

Toyota Prius II has a curb weight of 1.3tons and has a drag co-efficient of 0.26.

A vehicle of this spec. will easily have a range of 100 miles.

Power(kW) = Voltage(V) x Current(A)

Charge(Ah) = Current(A) x Time(hours)

Energy(kWh) = Power(kW) x Time(hours)

Energy(kWh) = Voltage(V) x Current(A) x Time(hours)

Energy(kWh) = Voltage(V) x Charge(Ah)

40Ah x 12v = 480Wh

For 104 batteries:

104 x 480Wh = 49920Wh ~ 50kWh

This means you can drive the 2 x 50kW motors at full power for half an hour.

Assuming the Mass-EV travels at 80mph using 80kW this will give it a 50mile range.

At 40mph the motors will use 1/4 power or 20kW total (inverse square law).

This will last for 2 hours and cover 100miles.

At 20mph the motors will use 1/16 power or 5kW total for 10 hours and cover 200miles!

Why you would want to drive for 10 hours at 20mph is anyone's guess :-)

2ton = 2 x 1016kg

80mph = 80 x 0.44704m/s

Kinetic Energy(J) = 0.5 x Mass(kg) x Speed(m/s) x Speed(m/s)

Kinetic Energy(J) = 0.5 x (1016 x 2) x (80 x 0.4470) x (80 x 0.4470)

Kinetic Energy(J) = 1016 x (80 x 0.4470) x (80 x 0.4470)

Kinetic Energy(J) = 1299470J or 1.3MJ

To transfer that energy efficiently I have file patent on the "Brushless DC Motor without Permanent Magnets"

which will control the voltage output in generator mode in the same way you control the output voltage of an alternator in your car.

This removes a complex and inefficient voltage dropping/inverting controller which is normally needed to recuperate this energy.

The patent motor makes the Mass-EV extremely efficient at regenerative braking finely matching the output from the motor/generators to the capacitors.

This is very important to make the range of the vehicle far more consistent.

If you think about it, when you decelerate from a motorway to reach your destination you would waste 1.3MegaJoules of Energy.

Energy(J) = Capacity(F) x Voltage(V) x Voltage(V)

Energy(J) / Capacity(F) = Voltage(V) x Voltage(V)

SquareRoot(Energy(J) / Capacity(F)) = Voltage(V)

Voltage(V) = SquareRoot (Energy(J) / Capacity(F))

The largest value capacitor is a 5000 Farad 2.7v ultra-capacitor measuring 80x150x64mm

or roughly a quarter of the dimensions of the 40Ah battery

For 5000F Capacitors:

Voltage(V) = SquareRoot (1299470 / 5000)

Voltage(V) = SquareRoot (259.894)

Voltage(V) = 16.1212v

6 x 2.7v Capacitors = 16.2v

So 6 Capacitors would store all the energy when decelerating from 80mph to zero.

This is quite a pleasant surprise since I originally anticipated about 10% of the battery capacity.

This means the budget of £500 per vehicle for super-capacitors is about right.

This is a shot of the Mass-EV parked outside my house

I took a photo of my street and superimposed the Mass-EV into the shot.

I did this so I could see the relative size of the body.

If you are interested the animations were done in blender, the imagery is done in gimp and the graphs were done in scilab