[clug] Canberra electric vehicles group - first contact

Alex Satrapa grail at goldweb.com.au
Tue Feb 2 16:17:51 MST 2010

On 02/02/2010, at 20:25 , Paul Wayper wrote:

> Fundamentally pretty much all batteries are fast to discharge and slower to
> charge.  This is improving with Lithium batteries but taking the load from
> regenerative braking is still dumping too much power into the batteries too
> quickly.  ...  Using the big
> capacitor bank to power the vehicle as it takes off in preference to using
> battery power will also save battery life.

Other alternatives that have been explored elsewhere involve using a hydraulic motor to drive the wheels. You have one big-arse electric motor powering the hydraulic pump, which then drives the wheels. You then have a closed can full of compressed air with a hydraulic piston, which is used to store the energy from slowing the car down.

When starting the car up again, the energy from the compressed air tank is used to drive the hydraulic motors.  Alternately, use a flywheel.

> ... You could have a bunch of
> switches - "maximise range", "maximise power", "maximise ride smoothness",
> etc. - which then back onto a set of tunable controls - maximum acceleration,
> accessory usage, regenerative braking cut off point, etc. …

You open source guys and your fascination with cramming as many options into a UI as possible :P

> The best part, to me, is that no commercial car manufacturer is _ever_ going
> to attempt these things.

It amuses me that the new range of Mazda cars includes a GPS. The display is tilted to face the driver, and all interaction with the GPS is through buttons on the steering wheel. When the car boots up, the display shows a message roughly along these lines:

  "I promise that I will not interact with the GPS
   or entertainment system while the car is in motion"

But the car doesn't provide any interlocks to prevent you doing dangerous things such as watching the GPS screen while the car is driving. Nor does the car provide any means for the front passenger to interact with the navigation system.

Fewer controls. Focus on software that is smarter. If the driver pushes the pedal to the floor, *that* is when you switch to the "maximum power" programme. Once the pedal comes up and stays at a low setting, *that* is when you switch to the "economy" mode.

>  This is just too out there, too clever, too
> demanding on the user to understand what the car is capable of doing

The user shouldn't need to understand what the car is doing. The car should understand what the user is asking of it, and deliver to the best of its abilities.

A computer user shouldn't have to know about microprocessor architecture in order to look up recipes for apple crumble.

Do we expect all book readers to have an intimate understanding of the paper-making and binding process?

> We've got the opportunity to make
> things that are going to add so much value that everyone wants one, and we can
> make it open source.

The "value" in the future is going to be cars that take care of themselves and tell the user when stuff needs to be done. Estimate the range at current usage, and point out to the user, "if you slow down by 5km/h, you'll get 20km more range from this charge."

> By Stallman's Beard, I'm stoked about this!

Which brings me to another point: generally speaking, more choice is bad. Giving people too many options to make in any decision will hamper the decision making process.

At some point, we're going to have cars on the road that are powered by open source systems, and we're going to have to start legislating about who has authority to authorise particular software to be used in cars on public roads - and indeed, to restrict who is allowed to load new software onto a car controller.

As we move into a "drive-by-wire" future for automobiles, there's going to be more focus on safe software. The walled garden will be necessary to ensure public safety. Such regulation will probably take a few fatal deaths by lithium-fuelled fire, but it's inevitable. Lithium batteries are dangerous. High voltage electricity is dangerous. Make sure to take into account the process of loading new software into the car, and the mechanisms by which you can prevent malware from sabotaging vehicle or public safety.


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