This is a throughly enjoyable thread but I'd like to suggest:
- aging vehicle, individual repair costs decrease - what happens is the ones that fail from accidents get retired to a salvage yard and their remaining serviceable parts become the new source for transmissions, inverters, batteries, e.t.c. To claim "new car" repair costs 7-10 years later (aka., $8,000 for a battery) simply means the poster hasn't realized that individual repair costs go down over time. Heck, Orangeboy recently replaced a Prius transmission for a very low cost and there are a growing number of frugal, 3d party and do-it-yourself mechanics (aka., "Re-InVolt".)
- Toyota price reduction announced - "Toyota announced that pricing for first- and second-generation NiMH Prius hybrid vehicle (HV) replacement batteries have been reduced by more than 10 percent. The price of the 2000-2003 first-generation Prius battery has been reduced to $2,299, while the 2004-2008 second-generation Prius battery is reduced to $2,588. Prior to this most recent price reduction, both batteries were priced at $2985. " Sept. 2008.
- Partnership for Next Generation Vehicle included a hydraulic hybrid - before the program was killed for the hydrogen fool cells. There was a design for a pickup truck with hydraulic hybrid drive. Yet a decade later, they have yet to show up on the consumer market.
- Refuse pickup and postal vans - these are a natural home for hydraulic hybrids. I've long suspected the two-mode, Tahoes should have been hydraulic but we'll likely never know.
I try not to project performance numbers for technology I don't have 'in hand.' What I can do is offer some facts and data on our 1.5L NHW11 (2001-03) and 1.8L ZVW30 (2010) model Prius.
HILL CLIMB
Here are some benchmarks on an 8% grade hill near Huntsville Alabama. We are in the Tennessee River Valley and near the Piedmont Plateau:
Efficient Prius operation involves knowing optimum climb speed:
- 55 mph - the ICE is in a fairly efficient mode and this seems to correspond to hill climbing speeds of tractor trailer trucks. In short, I follow trucks up hills and match their speed (NEVER tailgating.)
- 65-70 mph - worst climbing speed in the 1.5L NHW11. The engine is running at peak power and has to enrich the mixture to cool the exhaust.
- +70 mph - the traction battery supplies the extra climb energy. The apparent fuel consumption goes down.
- 80 mph - our NHW11 finally depletes the traction battery just at the crest of the hill. Thereafter, an involuntary loss of velocity until flat land returns.
The 1.8L ZVW30 has significantly changed the hill climb profile:
The 1.8L engine incorporates a cooled exhaust recirculation system to reduce exhaust gas temperature. Also, the higher power output appeared to handle the hill climb energy. The only exception is use of a lower, 87 octane fuel appeared to put the car in traction battery drain mode above 80 mph.
There are aspects of the Prius transaxle that in one mode has elements of a series hybrid:
In normal mode, 1/3d of the power goes from MG1 and on to MG2. The MG1 counter torque is needed to allow 2/3ds of the power to flow through the planetary gear to the fixed, reduction gears. Using partial fractions, one can quickly calculate the Prius transaxle efficiency:
.33*(series_efficency) + .66*(mechanical_efficiency)
As for the Toyota patent issue, it has to do with using control computers to operate the transmission. The Toyota/Ford CVT system actually traces back to:
The classic electro-mechanical power split transmission developed by TRW and published in a 1971 SAE paper is the basis of today’s electric power split systems. G.H. Gelb, N. A. Richardson, T.C. Wang, B. Berman, “An Electromechanical Transmission for Hybrid Vehicle Powertrains,” SAE paper no. 710235, Jan. 1971 - "Comparative Assessment of Hybrid Vehicle Power Split Transmissions", Miller, John M., January 12, 2005
I am sympathetic that someone who doesn't have a Prius and believes they are competing with the Prius may not have current facts and data. Without 'skin in the game', it is easy to cite dated or in some cases, wrong claims. I'm just trying to bring current facts and data to the table. For example, traction battery replacement cost:
Other recommended sources:
- "Evaluaton of 2004 Toyota Prius Hybrid Electric Drive System" Stauton, R. H., Ayers, C.W., Marlino, L.D., Chiasson, J. N., Burress, T.A., ORNL/TM-2006/423, Dept. of Energy.
- "Development of New-Generation Hybrid System THS II - Drastic Improvement of Power Performance and Fuel Economy", Koichiro Muta, Makoto Yamazaki and Junji Tokieda, SAE 2004-01-0064.
I have more sources but these two are a good start.
Bob Wilson