Chevy Volt - Electric Car

[Sxotty]

Like 3 or 4 different systems in development, still not decided which of those will go into series production. Still testing, benchmarking etc.

Sxoty, it's much less influence than what you think. Braking/accelerating >>>>>>> aerodynamics as far as the consumption goes, since you will rarely be able to drive with constant speed for longer periods.

And we do compare the developments to other brands out there all the time, thus I know that those nubers are bogus. Either they pulled all the tricks to make it look good or just plain lies.

Read that link XXX

http://www.fueleconomy.gov/feg/hybrid_sbs.shtml

Those are actual numbers, they are calculated based on driving the vehicles what more do you want? They are not made up, they are not bogus, they are not there to make hybrids look good.

 

[Mintmaster]

_xxx_, I don't know what your problem is.

You said yourself multiple times that with city driving, consumption is dominated by fuels used during starting and stopping. Hybrids recover a huge chunk of that, so city mileage can get doubled. On the highway at constant speed, hybrids offer no advantage. Apply this to any car's consumption rating and voila - city becomes better than highway. Physically it makes sense too because at high speeds the external forces (drag, friction) on the car are greater, hence the engine has to do more work to cover the same distance.

I don't know why you're mentioning batteries. These aren't plug-in hybrids, and we're not starting the tests with the battery full and ending it with the battery drained. The only thing that matters with batteries is internal resistance, and that's not enough to take a big bite out of efficiency.

 

[_xxx_]

I was talking max capacity. Mostly the currently used batteies will barely suffice for a 30-second run until the gasoline engine has to kick in.

 

[Arwin]

Max capacity what? Speed? Accelleration? Up to 50km/h? Higher?

 

[_xxx_]

Electric charge, how much the battery contains. Starting up and driving on electric only will get you just so far with most models before the combustion kicks in because the battery is getting drained. Prius may be an exception due to the higher capacity aftermarket battery packs available for it.

 

[Sxotty]

Electric charge, how much the battery contains. Starting up and driving on electric only will get you just so far with most models before the combustion kicks in because the battery is getting drained. Prius may be an exception due to the higher capacity aftermarket battery packs available for it.

Or the Tesla, or the EV1.

You are right that most of the batteries are small, but they are not intended to run on battery, they are intended to store energy from braking in the battery.

Further the VOLT is a PHEV, not a HEV. Its battery is around 16 times bigger than the prius one.

 

[_xxx_]

I know what I know and that certainly isn't everything Always open for surprises. Looking forward to Tesla if it should really work trouble-free and nearly as good as advertized. Assuming they finally release it of course.

 

[Gubbi]

I would imagine that the high torque/efficiency of an electric motor at low (zero) RPM would be the primary reason for hybrids to be more economic in city environments, - not regenerative brakes. In a combustion engine you control the torque of the engine with the throttle, to get moving you need to apply your right foot and fuel economy tanks.

Cheers

 

[Arwin]

I would imagine that the high torque/efficiency of an electric motor at low (zero) RPM would be the primary reason for hybrids to be more economic in city environments, - not regenerative brakes. In a combustion engine you control the torque of the engine with the throttle, to get moving you need to apply your right foot and fuel economy tanks.

Cheers

Yes, definitely an important factor, as I've been saying. This is why it is sometimes even more efficient for the engine to run while waiting for a traffic light, charging up the battery. The cvvt engine picks an efficient rpm and charges the battery directly. It can also charge the battery as well as spin the wheels at the same time. The display in the prius which shows the different energy flows rarely gets boring!

 

[Mintmaster]

I was talking max capacity. Mostly the currently used batteies will barely suffice for a 30-second run until the gasoline engine has to kick in.

Like I said, current hybrids aren't plug-in, so capacity doesn't really matter much at all. More capacity can let you go longer without using the engine, but then you have to use engine power for a longer time to recharge it again.

The battery is there for two reasons. The primary reason is for regenerative braking, drastically reducing city mpg. The secondary reason is to help run the engine at its peak efficiency more often by letting the electric motor/generator take care of fluctuations in the power demand when possible. Neither objective needs a very high capacity battery since the energy comes entirely from gas.

PHEVs like this Chevy Volt are very different from current hybrids in that they are made to avoid gas as an energy source except for the longest of trips.

 

[Nappe1]

Yeah, normal EPA numbers probably don't apply to this since it's the only hybrid that can go such a long distance without gas (although the hybrid mode is insanely efficient). What I forgot to mention is that this car is a plug-in hybrid. Meaning that you can recharge it by plugging it into a wall socket so I assume you can go years without actually using a drop of gas as long as you don't drive long distances. I wonder how the transmission options are set up for this car. Does it let you decide when to go to electric mode (and thus limit performance?) like a normal hybrid or does it switch by itself when it needs to?

Engineering wise, there's probably not a lot different about this hybrid compared to others besides more/bigger batteries. I hope the performance numbers aren't too weird to figure out when comparing hybrid and electric modes.

GM's hybrid technology has some key things different compared to Toyota's (which is the most widely licensed of them all.) but I can't recal what are the biggest differencies. (I think, it had something to do with drive train, but cannot be exactly sure.)

it will be interesting to see this new market wars to develop... Toyota isn't far behind with their plug in version of hybrid. Last time I checked, most of the manufacturers said that they have production ready plug in hybrids ready, except Li-Ion batteries, which are needed instead of nickel caddium. (IIRC, Toyota said that the batteries are already ready, except they don't keep charge good enough in very low temperatures to their quality standards, so waiting for next generation.)

and I still think that the target still eventually is hydrogen fuel cell system, as the hybrid tech gives you easy way to bring fuel cells as option, without need of hydrogen fuel station in every corner in the city.

 

[Natoma]

Yeah, normal EPA numbers probably don't apply to this since it's the only hybrid that can go such a long distance without gas (although the hybrid mode is insanely efficient). What I forgot to mention is that this car is a plug-in hybrid. Meaning that you can recharge it by plugging it into a wall socket so I assume you can go years without actually using a drop of gas as long as you don't drive long distances. I wonder how the transmission options are set up for this car. Does it let you decide when to go to electric mode (and thus limit performance?) like a normal hybrid or does it switch by itself when it needs to?

Engineering wise, there's probably not a lot different about this hybrid compared to others besides more/bigger batteries. I hope the performance numbers aren't too weird to figure out when comparing hybrid and electric modes.

My mom and her husband would be one of those drivers. They use their car for grocery shopping and going to church. Sometimes they'll drive long distances, but 99% of their driving time is within 30-40miles a day.

They would fill up a tank of gasoline and then not have to refuel for years. This would be perfect for them.

 

[_xxx_]

Like I said, current hybrids aren't plug-in, so capacity doesn't really matter much at all. More capacity can let you go longer without using the engine, but then you have to use engine power for a longer time to recharge it again.

Also, there must be enough charge left for the next cold startup. So you have to make sure your batteries are charged sufficiently at the _end_ of the trip too.

 

[Arwin]

Most important thing about keeping power in your batteries, I think, is to keep them lasting longer. I think for cold startups, you are more likely to have a separate battery that is more suitable for that thing. I think the Prius has a separate start-up battery also.

 

[_xxx_]

Depends on the architecture, there are some with an extra battery, some with Ultracaps and some with only the high-voltage battery. The latter case is a bit more demanding.

 

[Frank]

and I still think that the target still eventually is hydrogen fuel cell system, as the hybrid tech gives you easy way to bring fuel cells as option, without need of hydrogen fuel station in every corner in the city.

Fuel cells are the least efficient and most expensive option by far. But their saving grace is that it allows the oil companies to adapt and retain their market.

The best compromise would be methanol fuel cells. Not very efficient compared to hydrogen cells, but much better if you take the fuel tank and fuel conversions into account.

 

[Sxotty]

Also, there must be enough charge left for the next cold startup. So you have to make sure your batteries are charged sufficiently at the _end_ of the trip too.

Not really.

Supposedly the chevy colt goes 40 miles on half its battery pack. It always saves 50% of the charge. So that is not going to be a worry at all.

 

[_xxx_]

That's not how batteries work. A battery should never go below ~70% of its nominal charge. In hybrids it cycles between 70% and 90% usually. When you'd go down to 50%, you wouldn't get to do it very often before the battery dies

 

[Sxotty]

That's not how batteries work. A battery should never go below ~70% of its nominal charge. In hybrids it cycles between 70% and 90% usually. When you'd go down to 50%, you wouldn't get to do it very often before the battery dies

Your wrong.

Sorry that is all there is to it. You ought to do a bit more research before making stuff up.

The cells they are using can be cycled 4000 times at 100% depth of discharge.

Edit: Perhaps you are trying to say voltage, but that is not the energy stored in the battery.

 

[_xxx_]

Making stuff up?

I'm working on that stuff, man And I'm talking energy, not voltage. I think you should do some research.

Look here for example: http://batteryuniversity.com/partone-21.htm

Li-Ion:

Avoid full cycle because of wear. 80% depth-of-discharge recommended. Re- charge more often. Avoid full discharge. Low voltage may cut off safety circuit

NiMH:

Avoid too many full cycles because of wear. Use 80% depth-of-discharge.
NiMH has higher energy density than NiCd at the expense of shorter cycle life.

Led-Acid:

Avoid full cycle because of wear. Use 80% depth-of-discharge. Recharge more often or use larger battery.
Low energy density limits lead-acid to wheeled applications

Only NiCD can take the discharge, so unless they're using those they have to stay within the boundaries. I doubt they'll be using NiCD though since it's toxic.