* Posts by Terry Stetler

4 publicly visible posts • joined 13 Sep 2008

GM Volt to deliver three-figure fuel economy

Terry Stetler
Thumb Up

Volt facts....

How it works:

It has a 16 kWh battery, of which all but 9.6 kWh are 'off limits' so as to extend the battery life; basically the computer won't let it discharge below 30% or over 90%. Said battery is warranted for 10 years or 150,000 miles.

The electric motor is a 3 phase 600 volt unit of 161 hp/45 kW (100 KW peak). Like all electric motors it's vastly more efficient than an ICE and gets its maximum torque from 0 rpm vs. over 4,000 rpm for a gasoline ICE.

Slow it isn't. Volt can blister a lot of cars on the road.

The range extender/generator is a 1.4 liter normally aspirated 4 cylinder with a 53 kW generator attached. This runs at very specific speeds (depending on load) and only comes on when the battery is at 30% or if the battery is too cold or too hot. This is in order to power the car until the batteries environmental controls bring it into the normal temp range, at which time it shuts down and the battery takes over. It also starts up occasionally for a few minutes just to keep its innards lubed.

Full time electric drive, no 'helping the ICE' only at low speeds like most hybrids.

The range extender powers the car by generating electricity which is buffered by the battery on its way to the electric motor. Very few losses compared to a conventional drive line.

No transmission, so no losses there.

Regenerative braking - stopping recharges the battery.

For the first 40 miles it runs on electricity only, then the range extender fires up and can power the car for an additional 300 miles.

They were going to use a larger tank for a 500-700 mile range, but so little gas was being used in tests it started to stratify so a smaller tank with a magnetic stirrer was subbed in. Besides that, how many people can hold their water 500-700 miles? :-P

Operating costs (based on $2.50/gallon gas and the overnight off-hour electric rate for the Detroit area)

Charge time @120v: 6 hours

Charge time @220v: 3 hours

Cost of overnight charge: 40-50 cents

Cost/mile in EV mode: ~1 cent per mile

Cost/mile in range extender: 3 cents per mile

Cost of an ICE 30 mpg car: 10 cents per mile

Energy efficiency and availability:

A study by the EPI and a green group was done 2 years ago and it showed that existing generating capacity in the off hours is more than sufficient for EV's in the foreseeable future. In addition to this most new generation for the last ten years is natural gas, not coal.

All told the efficiency of an EV power path runs like this: 72% for the car, 40% for the power plant and 90% for charging. This results in an overall efficiency of about 26%.

Buy a solar panel, put it on the roof so that you can sell power back to the utility, then use just part of it at night to charge the EV and that goes way up to almost 65%. Such panels are already on the market and getting cheaper very fast.

A run of the mill ICE powered car is lucky to get near 20% for the vehicle and then you have to account for the processing of the fuel.

Plasma rocket in new test with Brit supermagnet fitted

Terry Stetler

VASIMR mission parameters

"What about stopping?

By Tim Greenwood Posted Tuesday 7th July 2009 11:27 GMT

It's all very well accelerating at ridiculous speeds to get to Mars in just over one month instead of a year. But I hope the brakes are good because you might want to stop when you get there!!?


The NASA profile for a VASIMR Mars mission would be as follows;

1. Accelerate in Earth orbit then slingshot into a Mars transfer trajectory with the VASIMR still thrusting.

2. At the halfway point shut down the VASIMR, rotate the ship 180 degrees then re-start the VASIMR. Its thrust decelerates the ship on the way to Mars instead of doing a big burn just as you approach Mars.

3. Enter Mars orbit in a decelerating spiral, the opposite of what was done in Earth orbit. The end of this would result in the ship being in a stable Mars orbit.

4. The return to Earth would be the opposite.

Estimates are that, depending on the mission parameters, as little as a 35-45 day trip to Mars instead of the several months to a year or more using chemical rockets.

Obama: McCain can't email, remembers Rubik's Cubes

Terry Stetler

Obama's skewed polling

"Obama's base skews young, yet polls are still taken by dialing people's land lines and asking questions of whoever answers the phone."

That would explain things if Obama over-polled - meaning that his actual vote were higher than predicted by the polls.

Problem is that in all the late primaries Obama UNDER-polled, meaning his actual vote was lower than predicted by the polls.

This is due to two factors;

1. most polls over-sample Democrats vs. their actual support in the populace

2. the "Bradley Effect" - so named after Tom Bradley, an African-American 1982 candidate for mayor of Los Angeles. Bradley lead the polls consistently and by significant margins only to lose the election by several points.

The reason was that when confronted by a live pollster, in person or on the phone, white voters were found to choose the black candidate so as not to appear racist.

This didn't mean they were racist, just that they had been cowed by the PC'ers into thinking that if they chose a white over a black they would appear to be racist.

Terry Stetler

McCain's computer skills

Everyone please note that it has been fairly common knowledge in the US that McCain does not use a computer because his war injuries to his shoulders make it extremely difficult to use a keyboard or mouse. When you see him standing with one hand holding the other or otherwise not moving them about those too are because doing otherwise is painful.

Obama taking this line opens him to a blistering counterattack.