Prius Plug-in Lithium Ion Battery Replacement Costs

Actually, I have sort of the opposite opinion. Batteries are currently expensive, so there is a clear trade off between price and capacity that must be made for the average middle income consumer. The tax credit makes an unaffordable larger battery capacity affordable. This is fine if it causes an economy of scale that pushes the battery price low quickly and consumer price remains the same after the tax credit stops. However, the number of Volts sold do not achieve this economy of scale while the Prius Plug-In will, in my opinion.

I would like to have the larger EV range of the Volt, personally. But to put it in a larger context, the 16kWh of the Volt which allows 35 mles of EV of one person could be put in 3.63 4.4 kWh Prius Plug-Ins which would allow 54 miles of total EV evenly split between 3.63 people.

 

Prius PHV's preliminary number is 87 MPGe, not 84. That's the blended figure, not pure EV.

The reason it is blended is because the gas engine would filter out the unwanted miles and leaving just the easy miles to EV operation.

The production Prius PHV's battery capacity is 4 kWh using 3 kWh to recharge from the plug (per Japanese spec). Toyota USA said it'll get 15 EV miles. That comes out to 200 Wh per easy mile. That's the beauty of blended design.

The gas engine gets all the hard work. That's when it is most efficient. Battery gets the easy miles because recharging is slow and battery is expensive.

 

Fixed in my earlier post. I knew that, but missed it at a glance.

The Prius Plug-In ebrochure on Toyota USA's website says it is 4.4 kWh.
http://www.toyota.com/prius-plug-in/ebrochure.html

 

I agree with that. My point was, why stop at 16 kWh? The more battery the better to drive the cost down right?

By limiting tax credit at 16 kWh, there is no incentive to include more battery.

That's if you need to drive on electricity. Is it a want or a need?

If you make a trip less than 35 miles, you paid too much for the extra battery capacity, opportunity cost of not using the gas engine and the price of electricity to carry that gas engine + gas tank around.

My point is, there is nothing wrong with utilizing a full (both) powertrain in your plugin hybrid. You paid for it so you might as well use it. That's #1 rule to be green. Reduce, Reuse and then Recycle. Reducing redundancy is #1. Reusing is #2.

A better way to view it is, to divide your trip to use both gas and electric. High power highway driving could use gas. The others use EV. You get the best bang for your buck by utilizing both of your hybrid engines when they are most efficient.

 

I agree that the 16 kWh limit is arbitrary and distorts the price signal with a discontinuity at 16 kWh. But the battery capacity of an individual vehicle is only looking at part of the picture. The economy of scale is driven by the total battery capacity across all vehicles sold. So the number that matters is number of vehicles sold times battery capacity per vehicle. My argument is that a smaller battery capacity times a greater number of vehicles can achieve a greater total battery capacity.

Also keep in mind how private money is leveraged in the two scenarios. Selling 1 Volt with 16 kWh battery leverages one individual paying $32,500. Selling the same 16 kWh spread across 3.63 Prius Plug-Ins with 4.4 kWh each leverages 3.63 individuals paying $29,500 each, totalling $107,085. The latter is a much greater private incentive to build more plug-in cars, make money (given demand can keep up and right now I think that is a reasonable assumption), and increase total battery capacity.

As for structuring the tax credit, I think the incentive should be a based on the EV mile range, not battery capacity. That way efficiency is rewarded, not just putting a large battery in a vehicle. There should also be a taper based on the probability that range will be utilized.

I think you quoted a single sentence out of context, as my point was that my or any individual's personal preferences aren't the ultimate goal. Individually, I don't think anyone has a true need to drive on electricity, so it's all want on the individual level. On a national level, we need to have energy independence, which means less dependence on foreign oil.

Here's where I get confused by your logic. First, 16 kWh is a problem as a limit for the tax credit. But then later having 16 kWh is wasted battery capacity.

Personally, I think 16 kWh is too much expensive presently for a single PHV. The tax credit up to 16 kWh distorts this by making it affordable, but in the Volt's case not enough so that it drives down the price.

 

If I were to venture a prediction - I would say that by the time the Prius Plug-in Li-Ion battery need replacing - there may be an upgrade path for a more powerful battery pack with an software upgrade package. With plug-in and battery electric cars will generate less revenue via maintenance, auto manufacturers will likely offer *upgrades* to existing cars just to get current owner coming back to the dealerships.

 

I hope you are right, but I think that's wishful thinking. The problem with that idea from a car manufacturer's viewpoint is that devalues the price of a new car. People would choose to upgrade instead of buying a new car and they would make much more money selling you a new car than upgrading your existing one.

 

I guess I haven't been posting here enough recently...

No, you can't use an EPA estimate and then compare that to a vague marketing range estimate. There is no compelling reason why Toyota's 15 mile EV range claim is much different from Nissan's LEAF range claim of 100 miles (EPA 73 miles).

Remember, Toyota was not claiming the PiP would get an EPA all electric range estimate of 15 miles. Their claim is instead based on some unspecified driving conditions.

They have in the recent past claimed in writing that the PiP will achieve a European NEDC all electric range of 23 km or 14.3 miles. The same NEDC test gives the Volt 83 km or 51.6 miles (not 35) and the LEAF got 175 km or 108.75 miles.

Unfortunately, we don't know what EPA will report for the PiP battery recharge kWh at the wall socket so we can't do an exact wall-to-wheels efficiency calculation. I know usbseawolf2000 says the production PiP will have a 3.0 kWh recharge (versus 12.9 kWh for the Volt) but I haven't seen exactly where that information comes from (and he got the nominal 4.4 kWh battery size wrong).

Assuming, for the moment, that this is correct then we can calculate miles per kWh at the wall on electric propulsion:

14.3 / 3.0 = 4.77
51.6 / 12.9 = 4.0

So, according to the European test cycle the PiP is 19% more efficient under those assumptions.

This seems a bit implausible to me although it is at the outer bounds of what seems possible. But, it's based on a 3.0 kWh number of uncertain accuracy (EDIT: I found the www.toyota.co.jp press release based on Japanese test cycles where that numbers comes from -- we'll see if EPA measures the kWh the same way in the near future).

Also, the NEDC test is a city-oriented cycle in which vehicle weight (starting & stopping frequently) plays a larger role. For example, the LEAF scores about 12% better than the Volt in the EPA city electric mpge estimate but only about 5% better in the combined city/highway electric mpge estimate.

I'm going to wait for more evidence.

 

Toyota has been conservative about their estimates in the past and have met or exceeded them. For example, for the prototype, they were estimating 13 miles and people got 14. If you have an example where they gave an exaggerated estimate that failed to live up to expectations, please cite the example. I would argue there is no compelling reason to disbelieve Toyota b/c of Nissan's (or GM's) reputation.

I think a more reasonable assumption is that if the Volt only uses 65% of its battery capacity, then the Prius Plug-In will be at least that conservative as well. In which case, the usable capacity is 0.65 * 4.4 kWh = 2.86. The Prius Plug-In then does:
14.3 mi / 2.86 kWh = 5.00 mi/kWh, so it would about the same (technically very slightly more) efficient than the Volt. Of course, this still must be taken in context of a 4 seat compact Volt vs a 5 seat midsize Prius Plug-In.

 

The EPA has quite under rated the Volt as well as 35 miles has been the bottom of what I have come to expect out of the battery. With the average being at least 41, and in peak conditions 47-50 miles. You are correct though about the efficiency. By my own spreadsheet when taking in to account the 20% extra for charging the efficiency is somewhere around a low of 0.225kwh/mi to a peak of .306kwh/mile in worst case.

You would be correct that if it does get 5mi/kwh it will be more efficient that the Volt, and even some Leaf owners by that standard. mi/kwh is pretty dependent on a lot of factors.. Certaintly will be interesting to see where all these cars stand after several years on the road.

In reference to the radiator thread that would in fact be the one. The owner actually was given a bill for the repairs, and fought it through GM. So the bill they recieved was one that someone could expect to have paid had I brought in the car, as the dealership is the one that told that individual it was not covered under warranty. Like everything else it all comes down to the dealership you chose. I stand by my thought that battery replacement in a lot of these cars will not be a near term issue, and by the time they will need replacement the costs will be reduced over current levels anyway. Toyota sourcing their own lithium will surely be a big help to those going with the PiP in the long term.

 

My complaint was about comparing "what Toyota marketing said" or "what people got" on the one hand versus an EPA estimate which tends to be 20-30% more conservative than "what people can get" for all electric range estimates.

 

I'm looking for the PiP EPA sticker.

I suspect we'll see 87 mpge for 15 miles (using a combination of gas and electric), and then proceeding on at 49 mpg.

 

I meant that Toyota is conservative with their estimates compared to the eventual EPA estimate. I'll grant you that I gave a bad example with the Prius Plug-In prototype, so I'll give a better one: Toyota tempered expectations for the Prius c with an estimate of 50+ mpg city and the EPA estimate is 53 mpg city.

 

Or they said that about the c to temper speculation based on the Japanese and European cycles.

I meant the motor is small in terms of efficient use. A general rule of thumb is that an electric motor produces its peak power at half its rated rpm, and it drops after that. It produces power at most efficiency at 75% rpm rating. I'm sure the engineers did their homework, but if the system is optimized for Japanese driving, it might be operating in a less than ideal range. I think the biggest drag on the motor are the parasitic losses of being linked to the rest of the drive train. It's popular to poopoo the Volt's clutch, but it's a component that has been in automatic transmissions for decades, and the fact is, with one, M/G 2 could put all its power to the wheels while in EV mode.

 

If the electric motor is undersized, I suspect it isn't b/c of Japanese driving, but rather it is sized for the Prius Liftback.

Do you mean manual transmission? An automatic transmission has a torque converter and a manual transmission has a clutch. Anyhow, I think the opposite is true, that the Volt's clutch is why one of the reasons why it is has such low hybrid mpg. Since the engineers chose a smaller, less efficient engine for cost/noise purposes, I believe there were other compromises made which lowered its efficiency.

 

In conventional cars, the torque converter sits between the gas engine and the rest of an automatic transmission to connect them together while allowing some slippage such as when the car is stopped at a traffic light. The gear changing within the rest of an automatic transmission is done using clutches and multiple planetary gearsets.

In any case, the 2011 Volt has higher EPA city and highway mileage estimates than the 2011 Camry hybrid and 2011 Lexus HS 250h hybrid which use HSD with a 2.4L 4 cylinder engine. They both weigh about 100 pounds less than the Volt and have roughly similar performance but the Camry gets city/combined/hwy of 31/33/35 and the compact 250h gets 35/35/34. The Volt gets 35/37/40.

I do agree that GM likely made some compromises in order to reduce the implementation risk of bringing a car to market with several new technologies. Presumably they can do better in the next major model change around 2015 or so by using a specially designed or modified engine rather than an existing one and perhaps further tweaking their transmission and control strategies much like Ford and Toyota have done with some of their newly redesigned 2012 hybrids.

Most actual Volt owners will have purchased the car in order to drive the large majority of their miles on battery power so modest changes in gasoline mileage will not have a large impact on their annual gasoline consumption.

Also, with a little experience learning the efficiencies of different driving modes, it is not difficult to get 42/42/42 in the real world during significant extended range gasoline driving. I achieved that during a week without plugging in just last month in 50-60F weather.

 

One thing I am curious about is how the EV efficiency of the PiP changes between 40, 50, and 60 mph. My knowledge of the inner details of the HSD starts to get fuzzy for the model years after the 2004 Prius which I own. I know some changes were made for the 3rd gen Prius that the PiP is built on. I'm uncertain, but my impression is that in order to stay in EV mode beyond 46 mph the transmission needs to free-spin the gas engine and this will add friction losses. I'm curious how significant this will be, especially when combined with any lower efficiency from having to drive the electric motor towards the top end of its design space. In contrast, at 60 mph the Volt uses its planetary gears to combine both electric motors with each at lower and more optimal RPMs.

Even if the PiP is significantly more efficient as an EV in city driving versus the Volt or LEAF it might lose that advantage in steady speed highway driving at 55 or 60 mph. Many drivers with a 20-40 mile daily commute may spend most of their trip at those speeds.

 

I'm guessing thats why the pip gives up on electric all together at 62 mph.

 

That's the threshold for HV mode. For EV, it's 62.1 mph (100 km/h).



That photo from my play with the early model PHV was quite exciting to witness, a clear step up from the regular model. There are a few brief video-clips available on my (priusguru) channel on YouTube.
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