Lightning/Roadster comparison

SteveF · 08-13-2008, 08:18 AM

Quote:

Originally Posted by Finkenbusch

.....stunning styled Lightning with inwheel motors

Oh boy. A car for about a quarter million dollars that will handle like a truck with its in-wheel motors. I can hardly wait.

Finkenbusch · 08-13-2008, 12:38 PM

Concerning the price-range, there are more expensive projects underway in the US - see the Ultimate Aero EV

(^click on the picture^)
Dont overlook that SSC company hold still the world record for selling the world fastest production car today - and you will like, its US build.

Regarding the stunning beautiful british "Lighning"

(^click on the picture^)
The truck handling, you mentioned, with in-wheel motors may be a double sword knife indeed - has to be tested on the track.

Experts claim that the four wheel individual power supply to the wheels has so much benefits on curvy roads (thats where the Teslas are naturally mostly driven for fun & tested) that it outweighs the (theoretical drawback of) higher unspung masses on race tracks - at least on public roads with a speed limit of 90 miles thought that has to be weightet against each other.

dpeilow · 08-13-2008, 12:57 PM

Check out the FAQ on the Mini prototype that uses the same motors:

http://www.pmlflightlink.com/motors/hipa_faq.html

Quote:

High unsprung weight?

The unsprung weight has increased by less than 2 kg over the original standard Mini. This has been achieved in the first part by removal of the disc, brake caliper, half shafts and cv joints. Secondly we have designed a very light motor and electronics system. As a comparison the power electronics (included inside the wheel) is around 20 times lighter than the lightest currently available alternative! The motor is around 5 times lighter than the closest rival. So we have a 350v 400A continuously rated (0ver 600A peak rating for a few seconds, although this has so far not been used!) system which weighs less than 24kg total.

Finkenbusch · 08-13-2008, 01:59 PM

There are more very interesting links to the company PML Flightlink, you mentioned delivering the underlying Lightning technology.

If this claims become only partly true - Tesla is looking pretty old-fashioned - especially the logical use of a battery / super-capacitor combo (used and proven as reliable in many public transport / metro systems in Europe) for close to 90% effectivity regenerative braking is very attractive.

More about Electric Lightning Technology:
NanoSafe™ from Altairnano Inc.

The dashboard the company offers for EV as of the shelf product today (including SAT navigation) would have done well on the vanilla conservative Tesla dashboard.

Click pictures below

DaveD · 08-13-2008, 02:35 PM

Ah, so those are new-fashioned, innovative bricks acting as chocks to keep the PML Flightlink Mini from rolling? I'm all for innovative solutions, but they have be complete solutions when it comes to life-safety issues like not rolling into oncoming traffic. Relying completely on regen braking doesn't work; the vehicle will move on a sloped surface.

Finkenbusch · 08-13-2008, 02:48 PM

Quote:

Originally Posted by DaveD

Relying completely on regen braking doesn't work; the vehicle will move on a sloped surface.

Maybe - you could use the supplied hand-brake in case - but thats not the point.

The point is that the car uses capacitors to recuperate the kinetic energy (not changing into chemical energy and back as if a battery where in place) and has a range of 1.000 Kilometers.
Kinetic energy is (very powerful - hit your head with the wall at 10 km speed and find out) used for example in big server-farms where the bridge as flywheel-concepts the time the diesels comes up in case of a grid failure.
Especially in the city you get largely extended milage as in stop & go traffic a enormous amount of kinetic energy is continuously build up and trashed - in that case to a capacitor which uses this energy for the next start - without hassling the battery.

Capacitors are very good at taking and delivering high loads in very short time - a field in which batteries struggle and heat up quickly.
So why Tesla is not giving that logical combo battery & capacitor a try is beyond many experts.

Knowing that the many metro system uses exactly that configuration since years.

SteveF · 08-13-2008, 02:54 PM

It will be interesting to see how the Lightning handles in comparison to the Tesla Roadster on curvy roads at "normal" speeds. Time will tell.

And sure the quick-charge battery technology in the Lightning is a great wiz-bang feature, but for my purposes, 99% of my usage of the Roadster will have it home happily charging in my garage overnight. In other words, not at all worth double the price of the Roadster for that feature, or whatever "extras' the Lightning has.

But I will grant you that it's a great looking car.

dpeilow · 08-13-2008, 03:12 PM

Quote:

Originally Posted by DaveD

Ah, so those are new-fashioned, innovative bricks acting as chocks to keep the PML Flightlink Mini from rolling? I'm all for innovative solutions, but they have be complete solutions when it comes to life-safety issues like not rolling into oncoming traffic. Relying completely on regen braking doesn't work; the vehicle will move on a sloped surface.

http://www.pmlflightlink.com/motors/hipa_drive.html

Quote:

Key features:

Full regenerative braking down to very low speed
Full holding torque at zero speed
Wide speed range
Built in brake resistor (for full charge regeneration situations)
Hand / parking brake option available
Heavy duty bearing system

http://www.pmlflightlink.com/motors/hipa_faq.html

Quote:

Safety concerns?

The braking system is fully dual circuit and each wheel is independently connected to the brake system. Each wheel has several levels of redundancy so any single failure will never prevent the vehicle from operating safely.

Someone said, "Ah but there is only one battery and if this fails or if a main fuse blows the vehicle cannot stop!” In fact when the vehicle is moving, the battery is no longer needed for braking power since the wheels themselves generate all the power needed to stop. This is the basis of regenerative braking and PML system can regenerate down to stop.

Joseph · 08-13-2008, 08:45 PM

I don't know anything about PML regen systems, but I'll tell you what I do know.

There's a guy around here in South Florida who has an AC Propulsion Ebox. As you probably know, Tesla Motors uses AC Propulsion technology for their invereter and regen system. I have met this Ebox owner numerous times, and I know for a fact that despite the car's very strong regen (at first, it's alarming) his car needs to use the brakes to come to a complete stop, otherwise it'll roll. Maybe PML has got this problem sorted out, but the Ebox, which uses technology similar to that in the Roadster, does not.

Besides, does anyone recall Tesla (I think it was Eberhard who told us this, maybe on his blog) that regen needs to be limited because too much gives the car unpredictable driving characteristics, or could even make you lose control. It was noted that this was a problem with the tzero.

Finkenbusch · 08-13-2008, 11:49 PM

Its not the matter that regen is used at all or if it works till full stop but how you store / use that regained energy.

- the key is that the energy is best stored to a cool capacitor (95% effectivity) and not converted (very uneconomical) into chemical energy - a battery cannot take that load in that short time and heats up (waste energy) instead of doing what it should do - store.