GM Volt Forum banner

1 - 20 of 40 Posts

·
Registered
Joined
·
128 Posts
Discussion Starter #1 (Edited)
There has been lots of discussion about GM rejecting the Volt's PHEV technology in favor of BEV technology.

Two factors when comparing PHEVs and BEVs are 1) battery versus battery/gas engine cost (for A: design and B: manufacture), and 2) vehicle weight (directly impacts vehicle mileage efficiency)

BEVs like TESLA and other long range cars have large, heavy, expensive batteries and a big mileage reserve. Volts have medium-sized, medium weight, medium cost batteries plus a backup "range-extending" engine/gas tank.

Some justifiably say that the cost of the batteries and of dragging around all the batteries needed to power a 300+ mile BEV is a waste for most people given their daily driving patterns. Being able to remove a battery pack (for example, 50% of the batteries in a TESLA) when doing only local driving would be desirable in reducing vehicle weight (increasing efficiency) but this does not reduce the cost of the battery as a whole. No manufacturer has done it. So Tesla/long range Nissan Leaf folks have the equivalent of 100 gallons of fuel (and the added weight) that they almost never use but it is there in an emergency or on a long trip. This seems very inefficient (in both cost and weight).

The Volt has greater complexity which means added design and maintenance costs but the engine appears to weigh considerably less than the extra batteries in the Tesla (or other long range BEV).

The Volt seems to have the advantage when it comes to vehicle weight (overall mileage efficiency) and driving range given that there is a gas station on every corner. The Volt also has the advantage of a lower battery cost. However it has the disadvantage of needing a gas engine, and the added design and EV integration costs the Tesla does not have.

So what are these extra Volt costs? I would argue that the Volt engine's development costs are shared over the millions of other I-4 engines that GM has produced over the years i.e., they are negligible. What is costly is designing the integration of the engine with the batteries (all the gearing and electronics). But once this is done and the Voltec platform is stable and reliable, the manufacturing costs also become negligible.

So in conclusion, the VOLT has the advantage of efficiency in weight, battery costs, low gas engine design/manufacture costs, and range. Its initial design costs may be higher than the Tesla/NIssan Leaf but once done, its manufacturing costs are probably on par with the Tesla's model 3/Nissan.

To me, this means that canceling the Volt was a bad idea in terms of both cost and driving efficiency. It is superior to BEVs in almost every way and will remain that way until batteries become considerably cheaper and lighter, and there is a charging station on every corner.
 

·
Registered
Joined
·
1,181 Posts
The difference is that GM management at least has the actual cost figures in front of them, when they do the analysis. And, part of the analysis isn't just the static situation today, but the future. Batteries are becoming cheaper, and there actually are charging stations on every corner, if you think about it.
 

·
Registered
Joined
·
2,767 Posts
Let me counter. Forget the Tesla S, it's old technology and bigger. The Bolt and Model 3 are lighter than the Volt (3 LR comparable) so there's no extra dragging weight around. BEV's have 1/3 the parts of a SUV leave alone the combined powertrain of both. The compacts Bolt, Niro, Kona, Soul are in the same price range (3 is pseudo luxury). Their prices will come down as battery prices come down but the Volt not so much as the small battery has a corresponding smaller decrease in price. The volts development costs are already written off so they are going to get much cheaper or they would sell them cheaper. There is not only three or four charging stations on every corner there are an additional six to ten on every block (I know you mean commercial but those will be built out with time until they out number gas stations). As it is right now, you can't buy gas in downtown Vancouver because the last gas station went on sale spring of 2017. If you run out of gas you are stuck till a tow truck comes (pretty sure it's sold by now). The assessment was 36 million dollars so not much argument could be made for keeping it. As EV's are sold, gas stations will convert over or be sold for the real estate just as you see gas stations boarded up across North America for the past while because cars get 30 miles per gallon and not 8. If running EV is not cheaper (it's about 8 to 9 times cheaper here) it will be in the future as gas gets more expensive and electricity gets cheaper. Wind power is now down to less than 4 cents a kilowatt including build up, maintenance and hooking to the grid. Alberta (the land of gas and oil) plans on getting wind power to supply 30% of it's needs. Other green energy is following. An example is Australia (where electricity is in short supply) where Tesla put the wind farm and battery farm in 100 days (or it was free) and to date, brown and black outs are down 90% and the utility company has saved 35 million dollars. You can't use 60's arguments in 2019. Did I miss anything?
 

·
Registered
Joined
·
1,230 Posts
While I really enjoyed my 2017 Volt I figured it was doomed when the Bolt came along. First off, side by side in the showroom people would see to similarly priced cars. One would have EV range of 53 miles and the other 238 miles. So some would assume that gasoline engine cost about 180 miles of range. If this was a second car they would not care as much for the REX.

However it was doomed when GM axed the Cruze and the majority of their sedan line up. Now they can end it without feeling "guilt" because "consumers" don't want sedans. GM's misconception is the same as Fords and Chrysler. Consumers are fine just buying sedans, but not ones that come across as being saddled with cost cutting measures.

If the Voltec platform had been employed in a CUV it might have survived, we won't know as GM declared PHEVs dead.
 

·
Registered
Joined
·
292 Posts
For me the Volt has too small a battery for daily use. If it had a 30kwh pack I would have bought a second one instead of a Bolt. For my driving habits it has to run the engine daily in the winter and some days in the summer. I really don’t like the ice experience for daily driving. For simple highway cruising it works great and is my preferred choice over the Bolt. No planning of stops, no long charge sessions, no fear of getting stuck in the cold. If they had put the same power train in a cuv/suv with a Bolt sized pack it would have sold really well. Problem is it would have cost far too much today.
 

·
Registered
Joined
·
981 Posts
I think the battery weights run around:

Tesla 80 kwhr about 1200 lbs
Volt 17 kwhr about 400 lbs.
A quarter of the Tesla weight would be about 300 lbs at around 20 kwhr
I know there is some structural overhead to protect the battery pack.
Perhaps newer battery tech in the Volt would have been lighter?
Anyone know how much the Bolt Pack weights?

How much does the 1.5l Volt ICE weigh? and how much for the extras to run just it?

If I had 600-800 lbs for the 1.5l ICE and ICE components, that might be an interesting comparison.

Also, I have to challenge the Voltec design concept a bit here using the benefit of hind sight is 20/20 vision and some things that are evident with modern day technology.
They had an on board a ev motor / generator and another larger ev motor that was coupled using hydraulic clutches to clutch in and out each component including the ICE output.
One motor they liked to use for ev starts and lower speeds, another for highway speeds.
Now the electric motors in most EV's, like the Bolt are setup, where one motor does it all.
What if the Volt simplified, where there was one EV motor/ Generator like the Bolt that always drove the wheels and re-gen'ed.
And the ICE was coupled directly to it's own generator (both might be same size as current one).
The ICE gen set only couples to the DC battery pack bus.
Then the mechanical part of this is simplified considerably.
To me this seems like a better path forward.
 

·
Registered
Joined
·
1,429 Posts
From a technological standpoint I think they killed the Volt prematurely but from a business standpoint I don't think they had choice. GM has exhausted the Federal Tax credit, Honda hasn't, that gives the Clarity a $7500 price advantage over the Volt. First time EV buyers are unlikely to understand that the Clarity is PHEV and the Volt is an EREV, it's a subtle difference, but they sure are going to understand that they will get a $7500 tax credit for the Clarity and none for the Volt.

Going forward the question of EREVs vs BEVs comes down to battery costs. EREVs only make sense if batteries are very expensive, we may have already passed the point where EREVs and BEVs have reach cost parity and we might not be that far from the point when ICEVs and BEVs reach cost parity. There is no doubt that GM has a very good idea about where batteries are going, if they thought that cheap batteries were many years in the future then they would have kept Voltec around but I think they feel that cost effective BEVs are very very close, in the luxury segment BEVs have already reached that point and within a few more years it will be true for mainstream cars.

From a complexity standpoint here is where the Volt suffers as compared to a BEV. The Volt needs two electric motors in addition to the ICE because one is used as a generator when the ICE is running, the Model 3 MR has only one motor, the Model 3 AWD and Performance have two but in that case the second motor provides AWD, the Volt is FWD only. The Volt has a simple transmission because they have to combine power from three sources, that goes away in a BEV, if you have one motor then all you have is a reduction gear, with the AWD BEV you have two motors but one drives the back wheels and one the front so you don't need to have both connected to a planetary gear as you do in the Volt. The ICE in the Volt has a catalytic converter, those are expensive, in a BEV not only does the engine and transmission go away so does the catalytic converter. Finally there is the space issue, the ICE takes up a lot of space without it you have a lot more flexibility in car design, you can have more storage space, you can provide more passenger room. Finally the performance of a BEV is better because with a bigger battery you can deliver more power and stronger regen braking, the Bolt beats the Volt in both acceleration and regen strength.
 

·
Registered
Joined
·
4,840 Posts
I think the battery weights run around:

Tesla 80 kwhr about 1200 lbs
Volt 17 kwhr about 400 lbs.
A quarter of the Tesla weight would be about 300 lbs at around 20 kwhr
I know there is some structural overhead to protect the battery pack.
Perhaps newer battery tech in the Volt would have been lighter?
Anyone know how much the Bolt Pack weights?

How much does the 1.5l Volt ICE weigh? and how much for the extras to run just it?

If I had 600-800 lbs for the 1.5l ICE and ICE components, that might be an interesting comparison.

Also, I have to challenge the Voltec design concept a bit here using the benefit of hind sight is 20/20 vision and some things that are evident with modern day technology.
They had an on board a ev motor / generator and another larger ev motor that was coupled using hydraulic clutches to clutch in and out each component including the ICE output.
One motor they liked to use for ev starts and lower speeds, another for highway speeds.
Now the electric motors in most EV's, like the Bolt are setup, where one motor does it all.
What if the Volt simplified, where there was one EV motor/ Generator like the Bolt that always drove the wheels and re-gen'ed.
And the ICE was coupled directly to it's own generator (could be same size as current one).
The ICE gen set only couples to the DC battery pack bus.
Then everything is simplified considerably.
I believe that the Bolt battery pack weighs ~900 lbs.
 

·
Registered
Joined
·
605 Posts
I hate to say it but I think Elon's (admittedly biased) statement about the Volt is probably spot on. He said that while the Volt offers two technologies in one, it doesn't particularly excel at either one (EV or ICE). With BEV's now at the point that they offer plenty of range, I think the Volt is sorta falling into the "half arsed" category: it doesn't know what it wants to be. I think consumers are at the point that they want BEV's because they are ready to switch and don't want ICE maintenance.

For me, the Volt is still perfect. I still do 100% of my local driving in EV, minus the tiny amount for FMM and EMM. But when I'm ready to get my next car, it will be a BEV. That will happen whenever mainstream manufacturers start making sporty (non CUV) BEV sedan options.

Mike
 

·
Registered
Joined
·
3,440 Posts
I think many members will agree with the OP that a PHEV/EREV is a very valid kind of vehicle in today's world. After all, most people here have bought one or more. We will continue to see these kinds of vehicles from other manufacturers, and probably in greater quantities. They are not going away soon.

The only question is why did GM step back. The answer to that is in things that are specific to GM, not the industry as a whole. bjrosen pointed out the tax credit and competitive pressure from the Honda Clarity. In addition, GM hasn't been making much money on small cars in general, and has probably made nothing or next to nothing on the Volt. One main benefit they have gotten from the Volt is the ZEV credits, but they don't need those any more because they get more from the Bolt, so they might as well focus on making as many Bolts as they need for ZEV credits. In short, GM has no need for the Volt regardless of whether some people really want them. They are not a hybrid company, they are a truck company.
 

·
Registered
Joined
·
1,230 Posts
If the old ZEV formula holds true each Bolt sold replaces [1] three Volts. Which means, why have both when one will clearly do the work of both and you can produce far less of them. Yet GM made sure to kill the Volt when it killed the Cruze and other sedans to mask the real reason : it does no give them enough ZEV credits vs the cost. So the volume of Bolts to be built comes down to how many credits GM needs and absolutely no more than that. GM is certainly big enough and geared up enough to produce many times the Bolts they did produce but I am convinced they don't want to. CARB credits effectively ran out between 20k and 25k units, so any wonder why the Bolt numbers are what they are? The rules changed at the end of 2018 with regards to CARB/ZEV credits that the "travel" rule phased out but companies were allowed to bank credits that expire in 2021... just in time for the Cadillac line to take over.


The big threat is GM dropping the Bolt after only one generation. The next question is, will GM limit the number of Bolts made even further than it already has since the travel rule is gone. The travel rule was likely the ONLY reason for nationwide sales.



On a side note, the ICE component of the Volt probably weighs in at less than the battery weight in Volt and that is counting the gasoline.




[1] https://www.ucsusa.org/clean-vehicles/california-and-western-states/what-is-zev
 

·
Registered
Joined
·
3,349 Posts
Interesting read. Thanks for posting it.

Bottom line from that read, California is distorting the EV market in all 50 States by allowing credits to carry forward. The "travel" rule also distorted the market by allowing a CA sale to receive credit in the rest of the states. The "pool" rule is at least regional and requires a vehicle be sold in that region.

It also explains why GM is dropping the Volt.
 

·
Moderator
Joined
·
8,680 Posts
One advantage of having a bigger battery always on hand is it can deliver big acceleration or accept big regeneration with much less stress. The Volt's 18 kWh pack means accelerating at 110 kW is pulling over 6C out of the cells, while the 3 pulls over 200 kW and is still not even at 3C. That means less heating, and the ability to use more energy focused chemistries instead of more power focused ones.

Which is not to say that the Volt was the wrong choice at the time or is obsolete now - just that there are compromises made to achieve amphibian status.
 

·
Registered
Joined
·
444 Posts
I think the battery weights run around:

Tesla 80 kwhr about 1200 lbs
Volt 17 kwhr about 400 lbs.
A quarter of the Tesla weight would be about 300 lbs at around 20 kwhr
I know there is some structural overhead to protect the battery pack.
Perhaps newer battery tech in the Volt would have been lighter?
Anyone know how much the Bolt Pack weights?

How much does the 1.5l Volt ICE weigh? and how much for the extras to run just it?

If I had 600-800 lbs for the 1.5l ICE and ICE components, that might be an interesting comparison.

Also, I have to challenge the Voltec design concept a bit here using the benefit of hind sight is 20/20 vision and some things that are evident with modern day technology.
They had an on board a ev motor / generator and another larger ev motor that was coupled using hydraulic clutches to clutch in and out each component including the ICE output.
One motor they liked to use for ev starts and lower speeds, another for highway speeds.
Now the electric motors in most EV's, like the Bolt are setup, where one motor does it all.
What if the Volt simplified, where there was one EV motor/ Generator like the Bolt that always drove the wheels and re-gen'ed.
And the ICE was coupled directly to it's own generator (both might be same size as current one).
The ICE gen set only couples to the DC battery pack bus.
Then the mechanical part of this is simplified considerably.
To me this seems like a better path forward.
If you assume the Volt's "transmission" would be there with or without the ICE, since it's mass is primarily made up of the dual electric motors, then I imagine the 1.5L ICE + empty fuel tank + exhaust + associated other hardware is probably more in the 400-500 lb range.

I've weighed quite a few Japanese all aluminum 4 cylinders from the early 90's that are larger than the Volt 1.5L, and they usually range in the low-mid 300 lb range for just the engine. I imagine the Volt's 1.5L is in the high 200 lb range (say 275 lbs?), while the gas tank and few supporting elements should easily fit into a ~150-225 lb mass budget remaining with plenty of fudge room.

So I'd say ditching the Volt's 1.5L and supporting stuff would be equal to roughly doubling it's battery mass, which would be right about 37 kWh, which I think the market has proven isn't enough range to sell in huge quantities, as it's still a city car at that point.

Makes sense, as the Bolt is physically a much smaller car than the Volt on a length x width basis, and it still weighs ~100 lbs more. Probably most of that delta is in the battery pack.
 

·
Registered
Joined
·
11,416 Posts
2019 specs according to Car & Driver.

Bolt Base Curb Weight: 3563 lbs
Volt Base Curb Weight: 3543 lbs
 

·
Registered
Joined
·
128 Posts
Discussion Starter #17
One thing that surprised me was how much lighter the Model 3 is than the Model S. At the 3600-3800 pounds, it is similar to the Volt in weight. So the argument that an EV MUST drag around a huge amount of extra mostly unused weight no longer seems viable. The cost of batteries (though decreasing) is still an issue as is the lack of charging stations in most of the country. The fact that the user must "sign up" to use these charging stations (excepting Tesla where owning a TESLA seems to be the sign up process) remains a barrier compared to visiting a gas station and paying semi-anonymously with a credit card.

Quote: One advantage of having a bigger battery always on hand is it can deliver big acceleration or accept big regeneration with much less stress. The Volt's 18 kWh pack means accelerating at 110 kW is pulling over 6C out of the cells, while the 3 pulls over 200 kW and is still not even at 3C. That means less heating, and the ability to use more energy focused chemistries instead of more power focused ones.

Response: I am not sure there is any evidence that draining a battery faster by accelerating quickly in the Volt over-stresses its battery to any degree. Anyone have evidence to support this claim?
 

·
Registered
Joined
·
292 Posts
Based on what I see on the model side, discharge is far less damaging than charging. On discharge in our models we routinely discharge 5c continuous or more. The battery abusing classes discharge at 15c average. Bust ratings are 100c, but in reality they will do 50+ easily for a burst. Far beyond what we are seeing in full sized cars. But then we only expect 50-100 cycles until performance drops off. We still only charge at 1 or 2 c for best life although you can push up into the 3-4 c range for a short number of cycles.
 

·
Moderator
Joined
·
8,680 Posts
One thing that surprised me was how much lighter the Model 3 is than the Model S. At the 3600-3800 pounds, it is similar to the Volt in weight. So the argument that an EV MUST drag around a huge amount of extra mostly unused weight no longer seems viable. The cost of batteries (though decreasing) is still an issue as is the lack of charging stations in most of the country. The fact that the user must "sign up" to use these charging stations (excepting Tesla where owning a TESLA seems to be the sign up process) remains a barrier compared to visiting a gas station and paying semi-anonymously with a credit card.

Quote: One advantage of having a bigger battery always on hand is it can deliver big acceleration or accept big regeneration with much less stress. The Volt's 18 kWh pack means accelerating at 110 kW is pulling over 6C out of the cells, while the 3 pulls over 200 kW and is still not even at 3C. That means less heating, and the ability to use more energy focused chemistries instead of more power focused ones.

Response: I am not sure there is any evidence that draining a battery faster by accelerating quickly in the Volt over-stresses its battery to any degree. Anyone have evidence to support this claim?
Your response seems to be to a statement I didn't make. No one has suggested that using the full acceleration GM allowed you to have is damaging to the pack they gave you.

However, it is a factor in the design and a compromise GM made. You did notice that the 1100 pound Tesla pack carries more than five times the energy of the 430 pound GM pack, right? - and more than seven times the usable energy.

That's because Tesla uses a more aggressive, energy focused chemistry. Lots of factors go in to that choice - cycle life, cost, thermal stability, availability of materials, and maximum charging/discharge rates among other things.

Out in California they are trialling some buses that recharge enough for the whole route at a single stop in the middle of the route that's no longer than the normal stops, by dumping hundreds of kilowatts into the bus from an overhead system. It works, but only because the buses use a lithium Titanate based chemistry that can handle the massive charge rates. Those batteries are a lot more expensive and heavier per kWh stored, but the trade-off seemed to make sense for the role.
 

·
Registered
Joined
·
46 Posts
The Volt's system works great for me. All electric driving day to day and a gasoline system for road trips. No rental cars or superchargers needed.

The business case falls apart with the politicians. If I go to a Honda dealership and get 7500 off but not a Chevy, that's going to impact demand. Also, the California credits that favor BEVs over EREVs is a government driven decision that hurts the Volt.

Voltec is complicated but engineered to be reliable. The whole system is costly and it's the external subsidies that will make the Volts business case not viable, not the Volt itself.
 
1 - 20 of 40 Posts
Top