Volt potentially mechanically driven

[FenwickHockey65]

Originally Posted by a_Username

So if there isn't a mechanical linkage to the wheels, then it would be classified as an EV, correct? I gotta say though, the GMI thread on this is helpful.

Correct. This post explains it fairly well...

1. Leaving home with a fully charged battery pack provides 40 or so miles of driving range with the engine and generator inoperative. The 149-hp permanent-magnet AC motor draws electricity from the 16kWh battery pack to drive the front wheels through a 7.0:1 speed reducer/torque multiplier.

2. Like any energy-conversion device, electric motors are more efficient at certain operating speeds. When the Volt exceeds fifty mph, a clutch holding the planetary gear set's ring gear is released. A second clutch engages to connect that ring gear to the smaller of the two electric motors. Now both electric motors draw electricity from the battery pack and the effective drive ratio shifts to 2.16:1. Top speed is governed at 100mph.

3. When the Volt's battery is depleted to a 30-percent or so state of charge, the gasoline engine is automatically started to give the battery a rest. The clutch connecting the gasoline engine to the smaller electric machine closes so that this device, now acting as a generator, can provide electricity to the main electric-drive motor. Another clutch holds the ring gear fixed, yielding a 7.0:1 overall drive ratio between the motor and the half shafts powering the Volt's front wheels. This regime is used for speeds below 30 mph.

4. At higher cruising speeds, the planetary ring gear is again released, shifting the AC motor drive ratio to 2.16:1. The engine continues providing the power to spin the generator which in turn supplies the drive motor with electric current. In addition, the engine supplies torque to the planetary ring gear through the smaller electric machine. (This is the engine driving-the-wheels scenario heretofore denied by GM.) Operating in this regime, the Volt is both a series hybrid and a parallel hybrid.


I expect Edmunds and Jalopnik to issue retractions.

[a_Username]

Originally Posted by FenwickHockey65

Correct. This post explains it fairly well...

1. Leaving home with a fully charged battery pack provides 40 or so miles of driving range with the engine and generator inoperative. The 149-hp permanent-magnet AC motor draws electricity from the 16kWh battery pack to drive the front wheels through a 7.0:1 speed reducer/torque multiplier.

2. Like any energy-conversion device, electric motors are more efficient at certain operating speeds. When the Volt exceeds fifty mph, a clutch holding the planetary gear set's ring gear is released. A second clutch engages to connect that ring gear to the smaller of the two electric motors. Now both electric motors draw electricity from the battery pack and the effective drive ratio shifts to 2.16:1. Top speed is governed at 100mph.

3. When the Volt's battery is depleted to a 30-percent or so state of charge, the gasoline engine is automatically started to give the battery a rest. The clutch connecting the gasoline engine to the smaller electric machine closes so that this device, now acting as a generator, can provide electricity to the main electric-drive motor. Another clutch holds the ring gear fixed, yielding a 7.0:1 overall drive ratio between the motor and the half shafts powering the Volt's front wheels. This regime is used for speeds below 30 mph.

4. At higher cruising speeds, the planetary ring gear is again released, shifting the AC motor drive ratio to 2.16:1. The engine continues providing the power to spin the generator which in turn supplies the drive motor with electric current. In addition, the engine supplies torque to the planetary ring gear through the smaller electric machine. (This is the engine driving-the-wheels scenario heretofore denied by GM.) Operating in this regime, the Volt is both a series hybrid and a parallel hybrid.


I expect Edmunds and Jalopnik to issue retractions.

Any respectable news source would retract their articles, but notice I said "respectable." ...

So, what I take from this is that the Volt acts as an EV until a situation arises where it responds by acting as a hybrid; seems to me that this is simply trying to negate a disadvantage of an EV by adding this hybrid safeguard.

[Mr. Wyndham]

Originally Posted by a_Username

So, what I take from this is that the Volt acts as an EV until a situation arises where it responds by acting as a hybrid; seems to me that this is simply trying to negate a disadvantage of an EV by adding this hybrid safeguard.

A concept that's been the core of the program: An EV without the anxiety.

[FenwickHockey65]

Originally Posted by a_Username

Any respectable news source would retract their articles, but notice I said "respectable." ...

So, what I take from this is that the Volt acts as an EV until a situation arises where it responds by acting as a hybrid; seems to me that this is simply trying to negate a disadvantage of an EV by adding this hybrid safeguard.

Sounds right to me.

People are making a mountain out of a molehill with this. It's a total non-issue and in fact improves the performance of the Volt. There are just people out there who don't want to see GM succeed.

[Captain Awesome]

Originally Posted by FenwickHockey65

It's still the best car in this segment. The Leaf won't use gas at all but will leave you stranded at the end of a 100 mile trip, and remember how fickle EV ranges are. You could think that you have enough battery power for a 100 mile round trip but end up stuck 20 miles from home when outside conditions reduce the total EV range to 80 miles. The Volt doesn't have that problem because the Volt isn't a completely half-assed car, as is the Leaf.

So did GM kinda renege on the whole "Solely powered by electricity thing?" Yeah, sorta. Depends on how you look at it. The Volt will still be powered by electricity 99% of the time. If you need to pass someone on the highway, then the ICE will kick in and help out, which is the more efficient solution than straining the battery/electric motors. Once that's over and done with and you're back to cruising at 70 MPH or below, then you're running on electricity only again.

I don't understand why people don't "get" the whole "battery only = BAD IDEA" concept... I mean we have all been using Cellphones and Laptops daily for years and we all have run into the occasion where we do the same thing we did every day before but at the end of the day we go to use the thing and it's flashing that battery warning at you and you're praying it lasts long enough to get done what you needed to do or you are plugging it in. Batteries don't behave the same way repeatedly when conditions change, and there's nothing saying that a EV is going to be any different in this regard. Plenty of people are going to get stranded by these things. One day someone else will invent an EV with an ICE and claim that they solved the problem, and perhaps the Volt will be long gone by then and nobody will correct the new "inventor" for this lie.

[v6sonoma]

What kills me is people are pissed off about this "lie" that is actually a good feature of a well thought out design. Who cares what it's called! These vehicles are in a time like the SUV's of the late 90's early 2000's they weren't trucks they weren't cars and we still make up new names for them rather than call them wagons. The Volt will be a great product I'm sure but some people are gonna piss all over it because it's GM's product. I hope it comes out swinging and proves them all wrong.

[Hylton]

Originally Posted by DGthe3

If its true, its true.

For years GM has been saying that the Volt will be only electrically driven, that the sole purpose of the gas engine is to generate electricity. Lately, they've taken to calling it a electric vehicle. So unless they've changed a fundamental part of the design in the last few days ... GM has been lying.

Good point Davin. One of GM's past down falls was to take the public as a bunch of idiots. I was extremely proud of (what I thought was) the fact that the vehicle was a true EV and that the engine could actually be called a generator.

I still think the Volt is a wonderful vehicle but please call a spade, a spade....it's a Hybrid

[Hylton]

Originally Posted by Dragoneye

I have to disagree. The ability to mechanically link to the road in extreme circumstances does not define the vehicle's character. So they've not misled, because it doesn't change anything they've said...it will still drive on nothing but electricity 99.9% of the time.

Any vehicle that can hook up the engine directly to the wheels, is not an EV. Doesn't matter how long it's for or under what conditions. Spin it all you want but the Volt is a Hybrid.

[Hylton]

Here's a link to GM's website:

http://media.gm.com/content/media/us.../Oct/1011_volt


The heart of the matter is how you translate this paragraph:

"There is no direct mechanical connection (fixed gear ratio) between the Volt’s extended-range 1.4L engine and the drive wheels. In extended-range driving, the engine generates power that is fed through the drive unit and is balanced by the generator and traction motor. The resulting power flow provides a 10 to 15 percent improvement in highway fuel economy. "


That's like saying there is no direct mechanical connection (fixed gear ratio) in any GM vehicle with an automatic transmission. True statement isn't it?

[FenwickHockey65]

The way I understand it is that the ICE generates electricity directly to the second electric motor which works in conjunction with the larger electric motor. The second electric motor is like an overdrive gear.

This is all such a huge cluster****. The only people who really know what goes on when a Volt starts moving are the engineers, and they probably can't explain it in terms that everyone will understand.

[GTAHVIT]

sorry for being simplistic.

but I see two issues here.

One: the car is never mechanically powered. Electrically powered motors always "drive" the rear wheels. the caveat is that under low batter power and heavier load, the ICE helps to create the electricity that drives the car. Not to say that it mechanically drives the car. FWIW.. I really don't care how one might interpret this, but to me it is is what it is. Call it whatever you want but don't confuse the capability.

Two: As with any headline news, there is always a slant. it's a shame but its true. The good news here is Camaro5 is full of members who can do their own research and come to their own conclusions.

[FenwickHockey65]

The bottom line is that without electricity, the Volt doesn't run. Simple as that. If you ripped out the electric motors and battery and tried to drive the car, it wouldn't run off the gasoline generator.

[DGthe3]

Here is a graphic Motor Trend showing how it all works together:

http://www.motortrend.com/features/e...cks/index.html

As I think through this, I can see exactly why it was done. GM very carefully worded their press release about this, again with the goal of misleading us. There is a mechanical link between the engine and wheels: engine -> generator -> planetary gearset -> wheels. It is not a direct link as the generator is stuck in there compared to how a car normally opperates. But there has to be a mechanical link because of regenerative braking. With regen, the most logical setup would be to have the wheels driving the generator. Well, if you have wheels->planetary->generator and engine->generator ... you've got a mechanical pathway from the engine to the wheels. Now, at some point they realized the potential use of this and figured out a way to implement 'partial mechanical' driving mode to boost efficiency.

From an engineering perspective, its all very clever and they should be applauded for it. But it also goes against what we've been led to believe about the Volt, particularly since they started calling it an EV. I can't believe that the engineers were doing this while their PR and media people had no clue. GM has to be more competent than that.

Originally Posted by FenwickHockey65

The bottom line is that without electricity, the Volt doesn't run. Simple as that. If you ripped out the electric motors and battery and tried to drive the car, it wouldn't run off the gasoline generator.

But you could also drive it without ever plugging it in.

[Hylton]

and just to add to DG's comments above, we both think GM's Volt is technically far, far superior to anything else out there.