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tonybelding
Active Member
We don't. It's a big question mark, and I don't claim to have a crystal ball. However. . .
I think there are some reasons for optimism. Based on anecdotal evidence from Prius owners, I think many people will find it annoying when the ICE fires up, and they will seek to avoid that. I also think many people will understand that they save money when they plug it in, that's going to be one of the main selling points of the vehicle after all.
That's better than forgetting and then not being able to drive at all, isn't it?
I think the assumption that people will charge their cars at home, overnight, should work pretty well with PHEVs. If they miss once in a while, that's no big deal. If you can't find a plug away from home, it's no big deal. Charging at home most days for that first 40 miles of driving is the big deal.
You've got it all wrong. When the battery "runs down" it's not 100% discharged. It just goes into a more conventional HEV operating mode where the charge is maintained in a narrow range (only a small part of its capacity is being used), but it still serves as a load balancer. That means when you need to climb a hill or pass somebody on the highway, it can draw on both the ICE and the battery for that surge of power.
That makes a bit more sense. Some Volt bloggers said that it was 100% ICE power (effectively bypassing the batteries) when the ICE finally fires up. The ICE supposedly only spools up enough to keep the car going, and not to recharge the batteries.
I continue to go back to this Volt info page.
"The engine’s job will be to maintain the battery at a SOC of 30%, and will do so by continuously matching the average power requirement of the car once it is turned on. Those energy requirements will roughly be about 8 kWh in the city, and 25 kWh on the highway. Another interesting note is about the time course of recharging the battery on the road. If one tried to recharge it by maxing engine output, the cells’ temperature would get too high, so the idea of rapidly “refilling” it on the fly and then cutting off the generator wont apply. Rather, it seems, the engine will continue to run, constantly matching the needs of the car to keep the battery at 30% until you stop driving."
The above suggested to me that they would revert to nothing but ICE power once the batteries were down to 30%. I gather from what you say that it isn't quite so "cut-and-dry". Perhaps the batteries will go down a bit (say to 28%) for a quick pass, and then the ICE might spool up a tad more than needed to get back to 30%. There still is an issue that they don't plan to have much of a battery reserve once the ICE is finally brought online. So if you had a situation needing more than 70hp for any length of time you could be out of luck. Perhaps the top speed with batteries at 30% is less than when you have a full pack? I still wonder about long steep grades with luggage on the roof and a full load of passengers.
One option would be for someone to do a big push in Hawaii where nobody is likely to need to have a long range (and long days of sunlight are available for solar power). [ On the other hand they have a constant supply of fresh air, so smog abatement isn't a high priority there ]
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I listened to it after that post. "I do not care who I have to kill ..." even Martin, heh? But they did reiterate their intents to stay electric and standalone. It was nice to hear that from their mouth after all what happened. I guess we speculate to much and want to much from them right now. Anyone not happy with a 150mile range WhiteStar should just go elswhere and buy himself a hybrid. Why would it have to be from Tesla?
stopcrazypp
Well-Known Member
I think that is a good idea. It will be interesting to see how Fisker will address some of the problems with PHEVs. You brought up some good points that I haven't thought of in PHEVs. For example the point about the PHEV not having enough power. It is true when the battery is about empty you will limp along if you don't have a powerful enough ICE. That would be unacceptable in a performance oriented car. If you make the ICE more powerful you will lose efficiency and likely have to use a larger ICE. It all comes down to optimizing the configuration and I look forward to both the Volt and the Fisker to see how they come out.
The interesting point is that if the battery pack weight doesn't improve for Tesla, I can see why they might go to a PHEV. Currently the battery pack is ~900lbs. Even a with v6/v8 at around 400lbs, if you add a 200lb battery pack for ~50mile range, it still amounts to only 600lbs of weight. That is the big advantage of the PHEV. The downfall is that the volume required is much greater.
On the one hand, for a BEV whitestar the 900lb pack would likely mean a 4000lb car (not good for performance or efficiency). They can partly remedy this if they can find some way to integrate the pack into the car structure. Other wise they need to find some way to lighten the pack.
For a PHEV it would be likely be hundreds of lbs less. Of course there is still that issue with power delivery after the battery runs out, and the charge cycles (don't forget 100,000mi/ 50mi per charge = 2000 charges).
tonybelding
Active Member
Problems such as?
No, it is not true. I thought I had already explained this. When the battery is "empty" it goes into charge-sustaining mode just like a conventional HEV. I suppose if the ICE was truly gutless you could make a PHEV that would "limp along", but I have no reason to suspect Tesla, or Fisker, or GM would produce a car like that. (I have a nagging suspicion that Aptera might. But I'm probably being unfair about that.)
I don't want to give everyone the impression that I've turned against BEVs or that I want Tesla to get into the PHEV business. I'm just saying lets stick to what we know, not things somebody dreamed up.
PHEV and BEVs both have disadvantages.
BEV: large and expensive battery, limited range, no fast recharge, limited charging locations
PHEV: much more complicated system, requires much more durable (expensive!) batteries, still burns gasoline sometimes (particularly if the owner forgets to plug it in when he should)
So. . . They both have disadvantages, but the PHEV disadvantages put none of their burden on the owner. It's up to the manufacturer to work the kinks out of that more complicated system, and come up with more durable batteries. And even if the owner forgets to charge it up, at least he can still drive.
By comparison, the limited range and recharging options of the BEV are something the owner has to work around, lest he find himself stranded somewhere.
Time will favor BEVs. Batteries will gain capacity and reduce in cost. Charging stations will be set up more widely. Also. . . PHEVs are attractive because they leverage existing ICE infrastructure, but as that infrastructure withers (which admittedly will take decades) their advantages will fade and turn into liabilities.
But right now the auto industry is in the early phase of a race to produce *EVs of whatever kind they can get on the road and get people to buy. They aren't trying to come up with the car of 2030 or 2040, they're trying to come up with something they can sell in 2010-2012. In that race the PHEV is a pretty attractive proposition -- especially for those like GM who are already heavily in the ICE business. Tesla not so much, but we'll see.
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TB wrote:
"And even if the owner forgets to charge it up, at least he can still drive."
IF he/she remembers to put gas in too!
Two scenerios. Which will play the most?
Two ways of filling so there a good chance that one of them will be avalible when needed.
OR
Two ways of filling so one might think the other will take care of the problem when neither was addressed.
"And even if the owner forgets to charge it up, at least he can still drive."
IF he/she remembers to put gas in too!
Two scenerios. Which will play the most?
Two ways of filling so there a good chance that one of them will be avalible when needed.
OR
Two ways of filling so one might think the other will take care of the problem when neither was addressed.
stopcrazypp
Well-Known Member
That is exactly the problem. You need an big engine that will be able to pull the car along even without batteries. This means when you are driving in battery sustaining mode you aren't going to see much improvement in efficiency at all. The Volt is planning to have a 71hp ICE so I do see that limp mode problem coming along for GM.
Again as I said it would be interesting to see an actual series PHEV and see if they optimized it enough so the battery still has enough juice to avoid the "limp mode." I know with the right amount of engineering you can probably avoid "limp mode" even with a less powerful engine. So far there has been no proven series hybrid avaliable to make comparisons.
Again I am talking about a performance oriented car. This means it has to handle peak power demands throughout its whole range. When it burns through the ~40miles of EV range, will it be able to supply the same level of power? There is also the consideration if the equipment can actually supply the power quickly enough even given a large engine. In a parallel hybrid, it is simple, just put the power of the engine to the ground. In a series hybrid, you have to go through at least the generator, maybe even the battery, before reaching the electric motor. The generator may not be able to output the same level of power as the ICE. The battery may not be able to charge quickly enough to take advantage of the full power of the ICE. Those are pretty big potential problems for a performance oriented car.
If you are just driving a PHEV for commuting then I guess you will never see these as issues. However, if it is put on trial for performance these are serious problems. Fisker and Tesla are performance oriented companies so I can see these as problems that need to be addressed.
Yes I understand the series PHEV is mean to be driven mostly in it's EV mode, but the ICE mode is still of concern.
I know I am making a lot of broad assumptions, and probably the engineers will have most of it figured out, so that is why I am saying it will be interesting to see how the Volt and Fisker turns out.
tonybelding
Active Member
Not sure why you think engine+battery will produce less power than battery alone?
Hello, this is my first post on this forum, but I have been reading up on these discussions for the past couple weeks.
I can see there being plenty of power for accerlation and passing even when the batteries get down to the 30% level like the Volt. However, this would never work for something like a track day, the ICE would not be able to keep up with the demand and the battery power would continue to drop if the ICE can't recharge the batteries fast enough.
I would also be curious to see how the long term works out on the batteries in the Volt since after those first 40 miles, they will be spending most of their life hovering around 30% SOC. I know Lithium Ions are better are not having memory, but they still degrade over time.
I can see there being plenty of power for accerlation and passing even when the batteries get down to the 30% level like the Volt. However, this would never work for something like a track day, the ICE would not be able to keep up with the demand and the battery power would continue to drop if the ICE can't recharge the batteries fast enough.
I would also be curious to see how the long term works out on the batteries in the Volt since after those first 40 miles, they will be spending most of their life hovering around 30% SOC. I know Lithium Ions are better are not having memory, but they still degrade over time.
Actually, keeping Lithium batteries in the refrigerator at about 30% charge is about the best thing you can do to preserve their life. Keeping them hot and fully charged, as in a typical in a laptop pc, is the worse. That's why so many people think that the Tesla batteries will fail after only a year. Their experience with Lithium batteries comes from using them in a laptop pc.
You are correct about the Volt not working well as a track car, but then that's not what it is designed to do anyway. I guess worse case in the real world would be heading west through Colorado, and your charge drops to 30% just as you start climbing from the plains into the mountains. I might be a long, slow trip up to the top of the Rockys. But then, a lot of regular gasoline cars have trouble climbing big mountains too. At least when you finally make it down the other side, the regenerative braking can probably get you back to 100% charge.
You are correct about the Volt not working well as a track car, but then that's not what it is designed to do anyway. I guess worse case in the real world would be heading west through Colorado, and your charge drops to 30% just as you start climbing from the plains into the mountains. I might be a long, slow trip up to the top of the Rockys. But then, a lot of regular gasoline cars have trouble climbing big mountains too. At least when you finally make it down the other side, the regenerative braking can probably get you back to 100% charge.
I think the concern is situations when you have engine only, and there is no more reserve left in the battery. Those long hill climbs don't give the small ICE a break to recharge the batteries. Cars like the Volt seem to be planning an ICE that can only generate about half the output that the eMotor can create, so when you are done tapping into battery reserves you are forced to drastically limit how much power the eMotor can make. So you are cruising along OK with 160hp of eMotor power available, then suddenly you only have maybe 60hp of eMotor power available because the batteries are spent. Sure if you are going up and down small hills the ICE & regen can "fill in the gaps" as you go back down a hill, but if you have constant hill climb for longer periods you don't give the system a chance to "catch its' breath" again.
Last year my wife (who supposedly doesn't care about performance at all) was car shopping and we were trying to decide between a Mazda 5 ( 153hp ) and Toyota Highlander Hybrid ( ~268hp ). We went for a Mazda 5 test drive in the "Emerald Hills" (near San Carlos), and she had the thing floored and it was just barely able to maintain the 45mph speed limit up that hill. The thing weighed about 3400 lbs which isn't all that heavy. She ended up on insisting on the Highlander because it went over the same hills with little effort and still got better gas mileage.
http://www.edmunds.com/insideline/do/Drives/FirstDrives/articleId=106717
"Although most minivan buyers aren't concerned with performance, the Mazda 5's power-to-weight ratio is a real concern. While the 2.3-liter engine feels sprightly in the Mazda 3, even in the 2,826-pound wagon version, the 5's additional 500 pounds puts a strain on the little engine.
Around-town drivers won't have much to complain about, but snowboarders won't be making any time up mountainous roads where the 5 really slugs along."
I can recall driving up steep hills in rental cars like Geo Metro, VW golf/rabbit, Subaru Justy, etc., all of which were "pedal to the floor" not able to keep up with more powerful cars, and all had well more than 70hp available.
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tonybelding
Active Member
I'm sure on the highways Out West there are some long grades that would challenge it. . . In fact, I know there are some long grades that are challenging for many ICE cars, they tend to overheat. But that's really an extreme example, isn't it?
In any kind of normal driving situation you don't demand 100% power continuously. You need peak power when you're passing someone, taking an on-ramp, climbing steep-but-short hills, things like that. A PHEV like the Volt should do just fine in those situations. As long as the ICE is producing substantially more output than your average power requirement, you've got no problem.
SF bay to Lake Tahoe is a good example where you need lots of continuous power to make it up the steep hills in the 2nd half of your long drive.
It is a very popular weekend getaway path.
How about LA to Lake Arrowhead / Big-Bear?
How about people living in Colorado?
Maybe they should sell PHEVs in flat states first?
It is a very popular weekend getaway path.
How about LA to Lake Arrowhead / Big-Bear?
How about people living in Colorado?
Maybe they should sell PHEVs in flat states first?
siry
Member
@stopcrazypp - we can use whatever batteries are available on the market - we chose to use the high energy density, relatively low cycle life batteries for the roadster. We could use LiPO4 cells for a different application. Several manufacturers offer cells of various chemitries and characteristics. One of the advantages of our approach is that it is chemistry agnostic. For example, in the future, it is conceivable we would offer different types of batteries for the same car to give customers choice (energy density vs. cycle life for example)
mt2
Member
Daryl, not you too! I don't know who started all this technology "agnostic" business, but I cringe every time I hear it. There is a contingent of us at work who have started a campaign to wipe out the misuse of the word.
Agnostic means that you hold a concept as unknowable. Does your approach assume there is no way to know what chemistry you are using? Or does it deny that there is any way to tell? Or that the existence of chemistry can neither be proved nor disproved? I doubt it.
Please, I beseech you, try to use the word neutral, or indifferent, or maybe nonchalant.
Some other terminology annoyances I hear far too often:
A "showstopper" issue is a major problem that must be fixed or else the product is dead.
Note these hardware/software definitions from Wikipedia:
Another pet peeve of mine is the use of the world "should" in product requirements. example: "When the engine is delivered we should have a starter installed." Does that mean that the starter comes with the engine (so no need to plan for it) or does it mean that someone better make sure to get a starter to go with that new engine? I have seen far too many specs where the term "should" was interpreted different ways by different people.
======================================
Putting those two together, what would this phrase mean to you? : "The transmission should have been a showstopper"
One possibility: "It was so good that we expected everyone to stand up and cheer!"
Another: "It had a problem so big we could have stopped deliveries, but we decided to ship anyways."
======================================
If a spec said "The transmission should last for 100,000 miles." do people interpret that to mean:
A: The original design is good enough and everyone can expect it to last that long
or
B: The transmission needs to last that long so work needs to be done to make it that good
?
A "showstopper" issue is a major problem that must be fixed or else the product is dead.
Note these hardware/software definitions from Wikipedia:
- an engineering or planning flaw which causes or can be shown to cause an operational failure
- a computer bug that prevents a project from going forward (as opposed to a minor bug that can be documented and coped with)
- In show business, an outstanding performance that causes the show to stop temporarily due to an audience reaction (such as uproarious laugher or standing ovation)
Another pet peeve of mine is the use of the world "should" in product requirements. example: "When the engine is delivered we should have a starter installed." Does that mean that the starter comes with the engine (so no need to plan for it) or does it mean that someone better make sure to get a starter to go with that new engine? I have seen far too many specs where the term "should" was interpreted different ways by different people.
======================================
Putting those two together, what would this phrase mean to you? : "The transmission should have been a showstopper"
One possibility: "It was so good that we expected everyone to stand up and cheer!"
Another: "It had a problem so big we could have stopped deliveries, but we decided to ship anyways."
======================================
If a spec said "The transmission should last for 100,000 miles." do people interpret that to mean:
A: The original design is good enough and everyone can expect it to last that long
or
B: The transmission needs to last that long so work needs to be done to make it that good
?
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