must be my light feet and summer gas...
maybe the mobil 1..

A/C on maybe 30% of the time..
Chevron 91.. the best gas on the west coast..

I bet people in the East Coast who pump 93's can do better...

I used to get 27mpg is my old prelude vtec w/ 93..
moved to Cali.. pump 91, it went down to 23~24 ish~

I think the biggest thing about hybrids is COASTING..
if you know u r gonna make a turn/stop.. just coast.. i dont mean coast @ 20mph and **** people off in the back.. but if you are going 50mph, let go the gas 1/4 mile before the stop or turn.. maybe even farther if no one is behind you..
Hell this works for all the cars..

 

glide heh.. that way you're not regenerating. If you're coasting, there are green arrows to the battery from the wheels. I'm sure you meant gliding?

 

I've had my 400h for three months now. The weather here recently went through a warm spell (60's & high 70's). I saw the mileage on a recent tank go to an average of 29.2... That's real mileage using a calculator. The display read 30.1 avg... Prior to that tankful, I typically got 25.5 to 27.2... I leave the AC off about 50% of the time, but I'm not sure how significant that is since it's electric and doesn't run off a serpentine belt... I'm sure it makes the engine cycle on and off more often to keep the hybrid battery charge up because of the AC draw, but I don't think it effects the mileage as much if it were running off a serpentine with typical compressor.
Jim

 

You are correct that in a conventional car the A/C compressor is belt driven by the engine. What must be realized is that it takes the same amount of energy to power the compressor when either motor driven by battery or belt driven directly from the engine.This energy comes from fuel burned. The difference being, in the hybrid the energy comes from the engine, to the generator, to the batteries, to the compressor motor, and finally to the compressor. Each of these energy converting devices (generator, battery, motor) has an efficiency less than one. Depending on where the engine is running on its efficiency curve, it may be require more fuel, decreasing mileage, to run the A/C on a hybrid then a conventional vehicle. Nothing is free, and every BTU of energy used by the propulsion system or any auxiliary system such as the a/c still comes from the energy in the gasoline burned.

 

I thought you did gliding in a plane without a motor or one of those kite things that people jump off cliffs with

 

I wonder if the AC voltage air conditioning compressor is more efficient than a standard automotive belt driven compressor. Any idea how many volts the 400h compressor is? 12vdc, 288vac? 3 phase or single phase? The electric a/c compressor could very well use less energy to produce the same desired effect as the typical belt driven. In the same way as a standard 14,000 btu portable window a/c unit can have different energy efficiency ratings depending on the manufacturer, and whether or not that unit is 120v or 240v also effects its efficiency.

 

The compressors are the same and A/C cycle efficiency will be the same whether belt or motor driven.. I am talking not about the compressor efficiency but the efficiency of the device driving the compressor- an electric motor or direct drive belt. Regardless of the terminal voltage to the motor, the direct drive belt will be more efficient than the electric motor and therefor require less BTU (fuel burned) input per BTU of cooling.

 

You brought up a good point, my first guess was that they would be almost the same in efficiency. But what about the way the compressor turns? With an electric compressor it can be set up to run at the most efficient RPM. But if the compressor is powered by the engine who's RPMs are always changing the compressor will be turning at slower than the optimum RPMs at times and other times it may turn at faster than the most efficient RPM.. My guess / vote is that the electric can be set up to run at maximum efficiency.

One other thing as far as driving a hybrid. I have been driving my gasoline vehicles for the past few decades using the same techniques I use for good fuel mileage in the hybrid. It just is common sense and by slowing down and trying to time traffic lights not only do I safe gas I also get better brake life.

The method I use is a result of being lazy as a kid. When I rode a bicycle and had to use my muscle power to build up momentum I usually tried my best to stay off the break so that I could squeeze out every bit of distance I could from all the muscle work I put into getting the bike in motion. When I was old enough to drive a car the same habits were applied to driving a car. It is all a matter of looking and planning ahead. Pay attention, if a light has been green for a long time and you are far of it will probably turn red by the time you get to it so just easy off on the speed enough for the light to cycle to red and back to green by they time you get there. Watch the car ahead of you if he is slowing down ease your foot of the gas before you need to use the break. It's all just common sense. Keep the tires inflated don't hang flags on the car that add to wind resistance. Keep your speed steady going up hills do not speed up. With older A/C units you were better off rolling down the windows but now with the new A/C compressors the added wind resistance from driving with the windows down uses more gas than turning on the A/C. An engine is least efficient when it is cold so plan your errands ahead and make your stops without letting the engine cool down. Remoter starters to warm up or cool down the interior are probably the biggest gas wasters.
These are some of the things I do that came to mind but I bet I could think up more but I bet with all the brain power on this forum we can come up with a long list of ideas and suggestions to save gas.

PS on the compressor thing a lot of people with fast cars live Vettes change the pulley size to make the compressor turn slower. This takes away less horse power from the engine but also lowers the A/C output the faster you spin the compressor the more H/P you use and the more gas you use so I think having the compressor spin at a fixed steady RPM will be more efficient.

 

Sorry I didn't answer your question re. A/C motor voltage:

Battery Pack- 288v
A/C motor- 288 volt
Power steering assist motor- 42v
Boost converter/inverter - 650v 3phase to drive motors.

 

The Boost Converter/Inverter takes 288vdc (the 30 - 9.6vdc hybrid batteries)and converts it to 650vac 3 phase to power the electric drive motors. Correct?

As I start to think now about all the specialty equipment in this vehicle that's specific to the hybrid, such as the above mentioned power steering, A/C Unit, Inverter, and other components, I wonder how far the 8 year/100,000 mile warranty goes... Is it only on the electic motors, inverter and hybrid batteries? What about the CVT? Maybe 6 years/70k? I think I better take a closer look at the warranty. Anyone know what it costs to replace some of these ancillary hybrid components? Probably not that inexpensive... What about the planetary drive gear?

 

Correct re. the boost converter/inverter.
As far as the CVT reliability, the mechanical components are much less complex than the typical hydraulic actuated automatic transmission. The power split device (planetary gear set) if adequately designed and built, should last as long as a differential in rear drive autos & trucks.

The motors and generator are permanent magnet rotating field, and should be very reliable. My concern, as is apparently yours, are the step-up converter/inverter, DC-DC converter and the Hybrid ECU.
Growing up with vehicles all mechanical and electric, I have always been concerned with the reliability of the solid state control devices and computers since I first observed their use. This is probable based on my ignorance and a hesitancy to accept change. ( I would love to have my 55 Chevy again)

That said, I have heard of no excessive failure rates with the on- board computers and ECU's that have been used many years now on all cars. You are correct, trouble shooting and replacement of these components will be expensive, as on any vehicle.

 

Riwyle,

Are you a Toyota/Lexus mechanic?

I've searched high and low online trying to find actual pictures of cut-away hybrid components to no avail. I'd love to see the internal workings of the different components (CVT, Planetary, Gen/Motors & Battery).. All I've found are illustrations of how they work...

Not to digress too much here (at the risk of being chastised by the moderator), I used to have a 55' Chevy Bel Air... 4 door hard top, blue. Mine was a straight six. Got it from my aunt with 17000 miles on it back in the early 70's... She paid $1500 for it brand new. It was cherry when we got it... Being the kids that we were, we beat the heck out of it. My father handed it over to the junk yard with title when it needed a valve job and he didn't think it was worth fixing! What a shame... I remember they had a propensity to rust out around the headlights, at least here in New England. Probably okay out west though... What a tank!

 

Lexus mechanic? No, just a retired engineer who loves to study and analyze all things mechanical. That is why I bought the Lexus hybrid- To see how good of a job they did designing and building a control system which would be seamless in controlling the power split device. They did well but not perfect.

 

You might enjoy this analysis then if you haven't seen it already...

http://www.engin.umd.umich.edu/vi/w4...Miller_W04.pdf

 

Take my advice and buy a 55 Chevy and I guarantee you won't regret it. If you look around you can find a nice one at a good price. If you take good care of it you can sell it at a profit if you get tired of it. I wanted a 62 Vette since I was a kid and 4 or 5 years ago I found a nice one in Idaho and had it shipped to NY

Here are some pictures of my 62 Vette, it is unusual because it has power windows in the fuel injected numbers matching 327 which is a pretty rare combination

http://img.photobucket.com/albums/v3...g?t=1178076213

http://img.photobucket.com/albums/v3...g?t=1178076627