Possible Production Volt Range Extending Engine Pic

[packardlust]

Originally Posted by MonaroSS

No, actually my point is that the Volt 'WAS' going to be less efficient than the Prius from the moment the auxiliary ICE was required. A Series Hybrid like the Volt (after the stored battery power has been consumed) are always less efficient than a Parallel Hybrid like the Prius, simply because power is more efficiently transferred via conventional mechanical transmissions than by generator to electric motor transmissions.

No, my point is that it now appears that GM is scrapping their plan to make the Volt a series hybrid and are now, with the use of the same 1.4 engine used in other applications of the Volt's new Delta platform, going to make Volt a parallel hybrid like the Prius is. It will in effect be a 2-mode hybrid for Delta. The exception being that they will have the software arbitrarily prevent the driver from using the ICE until after the battery pack reduces to a 30% state of charge.

In other words, GM is backtracking and watering Volt down to something that is nothing like what it started out to be....

The accountants are winning this war....

The write up with the pic is quite clear. The possible engine is being tested, NOT the Volt drive train. Nothing in the pic or the write up supports your theory. The pic is of an engine and trans axle and half shafts attached to some sort of device, most likely part of the test equipment. There may be part of the Volt drive train in the pic, but it is not obvious to anybody but an insider. Who has proof a series hybrid is less efficient? Since when is electrical transmission less efficient than mechanical transmission? There is no empirical proof for your statements in the photos or in the known info on the Volt

[ronald mcretard]

Originally Posted by MonaroSS

No, actually my point is that the Volt 'WAS' going to be less efficient than the Prius from the moment the auxiliary ICE was required. A Series Hybrid like the Volt (after the stored battery power has been consumed) are always less efficient than a Parallel Hybrid like the Prius, simply because power is more efficiently transferred via conventional mechanical transmissions than by generator to electric motor transmissions.

No, my point is that it now appears that GM is scrapping their plan to make the Volt a series hybrid and are now, with the use of the same 1.4 engine used in other applications of the Volt's new Delta platform, going to make Volt a parallel hybrid like the Prius is. It will in effect be a 2-mode hybrid for Delta. The exception being that they will have the software arbitrarily prevent the driver from using the ICE until after the battery pack reduces to a 30% state of charge.

In other words, GM is backtracking and watering Volt down to something that is nothing like what it started out to be....

The accountants are winning this war....

I don't see how you are making that assumption. AFAIK, charge-sustaining mode means the generator will power the electric motor AND charge the batteries to some extent (mostly the motor at times when high power is needed, charging the battery when sitting at a stoplight, coasting, etc.)

Originally Posted by packardlust

The write up with the pic is quite clear. The possible engine is being tested, NOT the Volt drive train. Nothing in the pic or the write up supports your theory. The pic is of an engine and trans axle and half shafts attached to some sort of device, most likely part of the test equipment. There may be part of the Volt drive train in the pic, but it is not obvious to anybody but an insider. Who has proof a series hybrid is less efficient? Since when is electrical transmission less efficient than mechanical transmission? There is no empirical proof for your statements in the photos or in the known info on the Volt

I agree. You're making assumptions with no factual support.

[MonaroSS]

Originally Posted by rueben44

^^^^^
You sound very knowledgeable but I don't understand something. You are stating I presume that Gm is making the Volt into something it was not originally to save money. At the same time you are saying it is becoming for efficient. Is that correct?

They are watering down the Volt to save money. Part of that change appears to be by making the Volt into a Parallel Hybrid. Parallel Hybrids are generally more efficient than Series Hybrids AFTER THE BATTERY HAS RUN DOWN, which will be after the 40-mile commute. During the first 40 miles the Series Hybrid is more efficient because it derives it's energy from electricity supplied via a household outlet and NOT gasoline. So GM is making the Volt more efficient after the 40 miles is travelled but the trade off is they need to use a bigger heavier engine which means that the Volt will be LESS efficient during the first 40 miles and may only get 30 miles before the ICE is needed. It is all about tradeoffs.

Originally Posted by packardlust

The write up with the pic is quite clear. The possible engine is being tested, NOT the Volt drive train. Nothing in the pic or the write up supports your theory. The pic is of an engine and trans axle and half shafts attached to some sort of device, most likely part of the test equipment. There may be part of the Volt drive train in the pic, but it is not obvious to anybody but an insider. Who has proof a series hybrid is less efficient? Since when is electrical transmission less efficient than mechanical transmission? There is no empirical proof for your statements in the photos or in the known info on the Volt

GM has dyno testing ability to test engines on their own or test engines combined with various transmissions. Why if, they are only testing the engine, would they not simply test ONLY the engine, rather than confuse the test results by adding transmissions that would not be used and which will distort the data?

In some circumstances series hybrids can be more efficient than parallel hybrids, especially if there is excessive stop starts and the weight of the vehicle is large and the engine is relatively small. But in the Volt v Prius comparison the series hybrid Volt set-up as first proposed would not be more efficient than the Prius parallel set-up. Why GM was going to use it though was because the series hybrid allows you to use electric only and that was to be for the first 40 miles. As that power was to be cheap electricity from a household electricity outlet, the lower efficiency is offset by the much lower cost of power from household electricity than from gasoline.

In order the minimize the inefficiency of a series hybrid you minimise the size of the ICE auxiliary generator so that the car does not carry around needless weight of a large engine. You also have the small ICE run all the time once in use to store up reserves of electricity in the battery so it can meet peak power by pairing it's own peak power output with a draw down from the battery for acceleration and feeding both through the powerful electric drive motor. But by now using the 1.4 motor designed to be used in this Delta platform to operate as a normal gasoline car it is way too large and heavy and makes the electric only phase of the Volt's usage far less efficient.

These are all complex matters of playing off efficiencies and costs to give the best package, but what is happening here is cutting cost for cost cutting sake and not for the best package.

BTW electrical transmission is always less efficient than mechanical transmission unless you use complex costly superconductor technology. You can Google it or see the Wiki link below where they discuss the comparative efficiencies.

Originally Posted by Wikipedia

The power from the combustion engine must run through both the generator and electric motor, so the engine-to-transmission efficiency is 70%-80%, which is less than a conventional mechanical clutch having an engine-to-transmission efficiency of 98%.

[BigAls87Z28]

It wont be like the Prius in that the ICE will not directly power the car, but power the electric motors that will spin the wheels.
It has been known for some time that they could not recharge the car 100% while driving. Once battery charge has been used up, the engine still acts as a range extender, not powering the wheels but acting like a generator.
The engine will be able to work under a light load at a low rpm where GM engineers can tune the economy of the engine to work with the work load the engine needs to put out.

[88ls1blazer]

OMG the world is ending...

How bout I wait 3 days when GM releases a different article w/ different info...

How many times do we need to have this happen? Everyone freaks out just to find out the info wasn't right in the first palce...

[BigAls87Z28]

Originally Posted by wagonertheidiot

I just find it funny that the only fuel efficient car to come out of GM in years isn't even out yet and is going to cost 45 to 50 thousand bucks.

Meanwhile honda is working on a new hybrid that will cost 19,500 bucks.

GM, is there some reason you can't built a cheap, fuel efficient car and honda can?

Whoa...when did the Volt's price get announced?
The only "price" I have heard is "40k" off rumors via Lutz's mouth.

Honda's Insight 2 will be a series hybrid, similar to the Prius while this will be another level ABOVE those two, having much better range and less impact on the enviroment then either of them.
How come Honda or Toyota cant build a two-mode system? How come they denounce plug in systems?
GM is working...well..worked and is going to produce a car that gets hybrid milage WITHOUT hybrid systems. Attach GM's advanced hybrid system, and a Hybrid Cruze would blow both of them away in range, mpg, and style. THat is unless you like the look of the egg shapped designs.

[MechEng]

Originally Posted by MonaroSS

A Series Hybrid like the Volt (after the stored battery power has been consumed) are always less efficient than a Parallel Hybrid like the Prius, simply because power is more efficiently transferred via conventional mechanical transmissions than by generator to electric motor transmissions.

Let me point out 2 simple facts.

A transmission has mechanical losses of about 20%.

A generator has losses in the 5 - 8% range.

I fail to see your logic.

The original concept had a 1L 3cyl turbo. So GM is going with a 1.4L non Turbo? Maybe this was the better option while being the most cost effective.

How many concepts are mechanically identical to their production counterpart?

Answer: I've yet to see one.

The plain and simple answer is not a lot of engineering goes into a concept. When a vehicle then goes to production engineering can change many things for many reasons.

In my opinion the production Volt will have very little in common with the concept. Except I have a funny felling that the production Volt will Exceed it's performance and efficiency numbers as an EREV and not as a PHEV.

[MonaroSS]

Originally Posted by ronald mcretard

I don't see how you are making that assumption. AFAIK, charge-sustaining mode means the generator will power the electric motor AND charge the batteries to some extent (mostly the motor at times when high power is needed, charging the battery when sitting at a stoplight, coasting, etc.)

People thought that the Volt was going to have it's ICE recharge the battery when at lights or cruising but that got binned a long time ago. Firstly the batteries heated up way too much. Secondly, the cost of the batteries is very high and to make the math work GM need them to last ten years.

They found that the batteries only had x amount of cycles in them whether they were full recharge cycles like when plugged in at home or short recharge cycles such as when stuck in traffic. It's a matter of certain heat and chemical processes altering the nature of materials. Below a certain level and it doesn't count as a recharge cycle above that level and you shorten the battery life. Unfortunately the levels were lower than hoped.

To make the batteries last ten years then can only afford to have say one recharge cycle per day. So now they can't recharge the battery on the move or they could end up with say three cycles per day and the batteries could be useless in under 4 years. And then who pays for the new ones? $10K for ten years of life is one thing, $10K for 3 years of life is a way higher operating cost.

So that’s why GM now labels that phase (see the graph) 'charge sustaining mode' not 'recharging mode' as was originally planned.

[MechEng]

Originally Posted by MonaroSS

Originally Posted by Wikipedia
The power from the combustion engine must run through both the generator and electric motor, so the engine-to-transmission efficiency is 70%-80%, which is less than a conventional mechanical clutch having an engine-to-transmission efficiency of 98%.

That number is close but not quite right. A generator will have maximum losses of 8% same with an electric motor. So your engine to wheel losses will be ~15%.

A mechanical Clutch does have ~2% losses. But a parallel hybrid doesn't have one clutch between the engine and the wheels. It will have a series of clutches and gears and the losses add up to ~20%.

Plus an EREV has the advantage of running the ICE in a constant more efficient state unlike the PHEV were the ICE will often be forced to work in the ICE's less efficient ranges.

[ronald mcretard]

Originally Posted by MonaroSS

They are watering down the Volt to save money. Part of that change appears to be by making the Volt into a Parallel Hybrid. Parallel Hybrids are generally more efficient than Series Hybrids AFTER THE BATTERY HAS RUN DOWN, which will be after the 40-mile commute. During the first 40 miles the Series Hybrid is more efficient because it derives it's energy from electricity supplied via a household outlet and NOT gasoline. So GM is making the Volt more efficient after the 40 miles is travelled but the trade off is they need to use a bigger heavier engine which means that the Volt will be LESS efficient during the first 40 miles and may only get 30 miles before the ICE is needed. It is all about tradeoffs.



GM has dyno testing ability to test engines on their own or test engines combined with various transmissions. Why if, they are only testing the engine, would they not simply test ONLY the engine, rather than confuse the test results by adding transmissions that would not be used and which will distort the data?

In some circumstances series hybrids can be more efficient than parallel hybrids, especially if there is excessive stop starts and the weight of the vehicle is large and the engine is relatively small. But in the Volt v Prius comparison the series hybrid Volt set-up as first proposed would not be more efficient than the Prius parallel set-up. Why GM was going to use it though was because the series hybrid allows you to use electric only and that was to be for the first 40 miles. As that power was to be cheap electricity from a household electricity outlet, the lower efficiency is offset by the much lower cost of power from household electricity than from gasoline.

In order the minimize the inefficiency of a series hybrid you minimise the size of the ICE auxiliary generator so that the car does not carry around needless weight of a large engine. You also have the small ICE run all the time once in use to store up reserves of electricity in the battery so it can meet peak power by pairing it's own peak power output with a draw down from the battery for acceleration and feeding both through the powerful electric drive motor. But by now using the 1.4 motor designed to be used in this Delta platform to operate as a normal gasoline car it is way too large and heavy and makes the electric only phase of the Volt's usage far less efficient.

These are all complex matters of playing off efficiencies and costs to give the best package, but what is happening here is cutting cost for cost cutting sake and not for the best package.

BTW electrical transmission is always less efficient than mechanical transmission unless you use complex costly superconductor technology. You can Google it or see the Wiki link below where they discuss the comparative efficiencies.

I doubt the added weight of an extra 0.4 liters plus a transmission would have the effect you think it will. Remember that with regenerative braking, aerodynamics is much more important than weight in this car (more weight = more recovered energy in regen, hence less detriment to fuel consumption).

Also, the transmission may only be part of the test setup. Maybe the actual electric motor isn't ready yet, and they are using the electric motors INSIDE the two-mode transmission to test the rest of the Volt powertrain. The point is this is one picture and you are drawing conclusions that only make sense if you have already made up your mind and don't bother gathering actual facts to support your claims.

[MonaroSS]

Boy some of you guys should do like 5 minutes of research.

A lot of you are going to be very disappointed. I told that to Bob last month and recommended he start getting some of the bad news out so he doesn't get his nuts roasted at the Volt's launch.

[ronald mcretard]

Originally Posted by MonaroSS

People thought that the Volt was going to have it's ICE recharge the battery when at lights or cruising but that got binned a long time ago. Firstly the batteries heated up way too much. Secondly, the cost of the batteries is very high and to make the math work GM need them to last ten years.

They found that the batteries only had x amount of cycles in them whether they were full recharge cycles like when plugged in at home or short recharge cycles such as when stuck in traffic. It's a matter of certain heat and chemical processes altering the nature of materials. Below a certain level and it doesn't count as a recharge cycle above that level and you shorten the battery life. Unfortunately the levels were lower than hoped.

To make the batteries last ten years then can only afford to have say one recharge cycle per day. So now they can't recharge the battery on the move or they could end up with say three cycles per day and the batteries could be useless in under 4 years. And then who pays for the new ones? $10K for ten years of life is one thing, $10K for 3 years of life is a way higher operating cost.

So that’s why GM now labels that phase (see the graph) 'charge sustaining mode' not 'recharging mode' as was originally planned.

I don't know where you are getting your information about the batteries heating up too much. From what I have read the thermal performance of the first packs was way better than GM had anticipated.

The reason they use charge sustaining mode instead of recharging mode is because charging the batteries with gasoline is much less efficient than charging them from the grid. You wouldn't want to take a trip, pull into your garage, and plug in your Volt only to find that the car recharged itself with gasoline before you got home (because you just spent $4.00 per gallon on gasoline instead of $0.80 per gallon equivalent on electricity).

[MechEng]

Originally Posted by MonaroSS

People thought that the Volt was going to have it's ICE recharge the battery when at lights or cruising but that got binned a long time ago. Firstly the batteries heated up way too much. Secondly, the cost of the batteries is very high and to make the math work GM need them to last ten years.

I never thought that. Why would the Volt's ICE be limited to recharging the battery at lights and at cruising? Now I understand that under acceleration the motor might not charge the battery and might only be working to maintain the charge state. GM engineers probably determined that maintaining a certain charge state is what is best for efficiency and batteries.

Are you aware of the properties of Li-Po batteries? They are quite different from NiMH batteries. And don't follow the same recharging restrictions.

Maybe you should review how new high efficiency furnaces work (with new types of controllers). By the look of the curve it's a similar principle.

[MonaroSS]

Originally Posted by ronald mcretard

I don't know where you are getting your information about the batteries heating up too much. From what I have read the thermal performance of the first packs was way better than GM had anticipated.

The reason they use charge sustaining mode instead of recharging mode is because charging the batteries with gasoline is much less efficient than charging them from the grid. You wouldn't want to take a trip, pull into your garage, and plug in your Volt only to find that the car recharged itself with gasoline before you got home (because you just spent $4.00 per gallon on gasoline instead of $0.80 per gallon equivalent on electricity).

The plan was never to fully recharge, just recharge enough to build a buffer so that acceleration was all down to the elctric motor from battery reserve and the ICE just had to supply cruise power. Now even buffering is out.

And BTW the difference is not between a 1.0 turbo 3-cylinder and a 1.4 turbo 4-cylinder that were both normal car engines. The original engine was way lighter and more efficient for lots of reason too complex to be inderstood here.....

[MonaroSS]

Originally Posted by MechEng

I never thought that. Why would the Volt's ICE be limited to recharging the battery at lights and at cruising? Now I understand that under acceleration the motor might not charge the battery and might only be working to maintain the charge state. GM engineers probably determined that maintaining a certain charge state is what is best for efficiency and batteries.

Are you aware of the properties of Li-Po batteries? They are quite different from NiMH batteries. And don't follow the same recharging restrictions.

Maybe you should review how new high efficiency furnaces work (with new types of controllers). By the look of the curve it's a similar principle.

Given the size and weight of the Volt and the output of the original engine most of it's power would be consumed in driving and it would have been during light cruise and at lights that it would have been freed up to do most of the recharging.... and nobody be so dumb as to say, "but the ICE isn't connected to the wheels it only recharges the battery" Please! The ICE's power turns the generator, which sends power into the battery pack whereupon it IMMEDIATELY leaves to go to the electric motor. If the electric motor draws less than the ICE and generator are putting out then it could recharge the battery but now they won't let the computer do that in order to protect battery life. Its all about compromise.

From the top of my head the Volt's batteries can't be charged more than 80% or let fall below 30%.