IL Corrects Volt Story: Batteries Will NOT Charge When Driving; GM Website Differs

[PhishPhood]

Originally Posted by 96_impala_ss

I thought that was clear from the beginning. Drive 40 miles charge, drive 40 miles. if you run out of charge the motor kicks in until you can find a place to charge/go home w.e.

isnt the average commute 40 miles from point a to point b and back?
the car is good for the average 9-5 joe. its not ment to replace every car on the road.

so stop the whining.

The question in my mind is after the initial charge is depleted what is the actual flow of energy.

It's still unclear from both GM's statement and the writer's impressions what actually happens other than the ICE runs nearly all the time after the initial charge is depleted.

Here is my interpretation based on the 30% - 80% comment and knowledge of the Toyota system. The vehicle is charged up to a max of 80-90%, never 100%, by plugin. It's then driven some distance at some speed in whatever weather conditions might be occuring ( bad weather, bad traction and strong winds will deplete the charge faster as will heavier loads and faster speeds ). Except for short trips the charge is depleted and the ICE kicks in.

When this occurs, I'm opining that an ECU with a predetermined algorithm decides how much of the 'input' from the ICE should go to powering the vehicle and how much should be 'kept' in order to maintain a minimum 30% charge on the battery pack.

Assuming that there is a regen braking system in place this will add some charge to the battery pack. Thus in driving situations with repeated braking, stop and go, the SOC on the battery pack may be replenished again somewhat so the ICE doesn't have to do as much work. However if, such as on a constant cruise along I 95 from NY to Florida, there will be little or no braking then after 40 miles the ICE will run the entire time.

For the entire trip the ECU will draw just enough power from the ICE in order to keep the battery pack at a minimum of 30% SOC. Drive from NYC to Miami and back, a distance of 2660 miles, the first 40 miles is gas-free and the next 2620 miles are under ICE power.

Supposition only until more is revealed.

[tamatt27]

Originally Posted by urarock76

Thanks for the post rob2299usa, but your info didn't clear this up for me. I thought the point of the gas engine was that it would be run at a constant, optimum rev while on. If that is so, isn't a whole bunch of gas energy going to be wasted when the Volt is stopped or traveling slowly and not using all the energy the engine is generating? Second, if the point of not charging the batteries with the engine is to reduce the charge/discharge cycles (a worthy endeavor), how does that true up with the use of regenerative brakes to charge the battery during engine on time...or is it that the regenerative brake system is turned off when the gas engine is on? Finally, not from your post, but other posters have said that while in engine only mode the car will get 50mpg? Is that true? That seems pretty high given GM's current models do not come close to that, and they don't carry the extra battery weight.

Very good point. If the VOlt would need all the ICE's power to run the car at 75MPH, then why would the car need the engine running at 25 MPH? It seems that electricity would be wasted.

[PhishPhood]

Originally Posted by rob2299usa

stopped = engine off for sure. also i would imagine that the engine can run at a point low enough to just keep the vehicle moving. if you were coasting down a hill, then the engine would probably shut off. regenerative braking is not engine power, therefore that energy WOULD be used to charge the battery. That's why I said that I imagine a situation (mountain driving) where you get enough regen to switch the engine off and drive another small distance in engine off mode.

i imagine it is definitely possible to get 50mpg due to the superior aerodynamics, the ability to regenerate energy from braking, engine stop/starts, and the fact that you only run the engine at a few efficient points.

It depends on how long a drive one makes, what the conditions are outside, how much 'cargo' is inside the vehicle, how efficient the ( 1.3L / 1.4L ) ICE is alone by itself, which fuel is being used ( gas or E85 ).

The maximum Fuel Economy rating is Infinity if the vehicle goes only a short distance between charges and never uses liquid fuel.

The minimum Fuel Economy rating would occur if the vehicle was never plugged in and ran on the ICE its entire life. In this case the rating would be whatever the FE of the ICE was alone by itself.

We don't know yet what will be the FE rating of the ICE running by itself. But...it's a relatively small engine pushing around a relatively heavy but aerodynamic compact vehicle. In this case I'd estimate that the ICE will have a FE rating of about 30-35 mpg all alone by itself. Thus if a trip was taken from A to B to A that used the full charge and the entire fuel tank ( 12 gallons?), then in perfect conditions with only the driver and no other cargo or passengers one could go 40 miles gas-free and ~440 miles on gas alone. That's a total of 480 miles on 12 gal of fuel or about 40 mpg.

The obvious point is that to usel the least fuel one should plan to use the Volt for the purpose it was intended. Short commutes. It can certainly drive across the country and back but that's not using its best characeristic.

Now in the future when there might be a plug-in infrastructure in place such as at every Marriott or Hilton or most parking garages then there's a HUGE HUGE benefit on long distance trips.

After the Volt comes out and is well-proven and I'm the Environmental Manager of Marriott, Hilton, et. al. I have a memo on the desk of the CEO that we have to install plug-in stations at all sites ( for a fee ).

[blawrence73]

Originally Posted by drew630

So basically after 40 miles the Volt becomes a basic, ordinary high mileage car? I.E., no gas motor off below 25 mph? If this is correct, this is a huge flaw IMO.

Totally agreed!

[logansowner]

Originally Posted by megeebee

This is not what I had been thinking. It was my impression that the engine did indeed "charge", as in replenish, the battery.


Also, what about that 3 cylinder thing. I though it was gonna be a small 4 cylinder?


.

That's what I thought too, even Lutz said on his Colbert interview that a "small 1.4 liter 4 cyl" would generate power. I was like most others, also under the impression it would charge the batteries too though.

Seems to me nobody knows all the details. Even the people correcting get something else wrong. Guess we'll know when it comes out though. Even still, I don't think that is a deal breaker. It would get my to college each morning and then part way home before needing any gas at all, which is quite the difference compared to my car burning through $65 a week, not including any other driving at all.

[tamatt27]

I sent this e-mail to Bob Lutz:
Mr. Lutz,

With the unveiling of the much-hyped Chevrolet Volt, there is still a bit of a mystery as to how the propulsion systems works. I wouldn't ask you to go into great detail about the subject, however there are a few things that many of us on GMInsideNews.com are unclear on.

The Volt will utilize the 1.4L gas motor as the onboard generator correct? Since this gas motor is intended to run at a certain RPM, is the HCCI engine being considered as an eventual replacement for the 1.4L?

Perhaps the most confusing thing about the Volt is whether or not the generator charges the batteries or simply applied voltage directly to the electric motors powering the wheels. There has been much speculation on this subject as most of us have thought the Volt's batteries will power the vehicle to the eventual 40-mile range (or until the batterys are at 30% charge). At which point we were under the impression the 1.4L generator would come on and charge the batteries, which would propel the vehicle. Is the flow of energy from the generator to the wheels through the batteries or simply from the generator to the electric motors?

That poses another question. If the batteries are NOT charged by the generator after they're down to 30%, could the regenerative braking charge them up enough for the Volt run on electric-only power for a short time? I do realize there is much about the Volt that cannot be disclosed at this time, but I do appreciate any response in clearing up this matter. Thanks,

---Matt S.---
Hopefully his response will clear all of this up.

[04bonnie]

For the price of this thing, it should do everything, and wash your dishes too! Not impressed, the Volt is over rated, sorry...don't see what all the hype is all about, it's practically taking over the news ticker, would like to hear other news besides the Volt.

[WishIhadatruck]

A lot of people keep saying the engine will be running at a constant rpm. I don't believe this to be true. I just read in the last day or so that they picked the 4cyl for 2 main reasons. 1, it already exists (or will). 2, if they used a smaller 3-cyl like in the concept it would need to run at much higher rpms much of the time where the 1.4L 4cyl motor can stay in the 2k-4k rpm range and therefore will be much quieter. It seemed to imply to me that the engine would vary rpm depending on the load required. Just like small Honda generators that are invertor based, they can vary their rpms depending on load but always provide the same voltage and frequency. This allows them to be much more fuel efficient.

A year ago I was convinced the Volt would charge the batteries back up and then allow another 40 miles of gas free driving but I'm sure that isn't the case anymore so this doesn't suprise me. Actually the more I think about it the more I think that using the gas motor to charge the batteries back up would be a complete waste of gas anyway since charging them up with the elec. plug will be much cheaper and won't use gas which I'd rather avoid using. I don't see why people see this as a deal breaker at all. I imagine the batteries won't just stay at 30% (considered fully depleted) but will probably be allowed to fluctuate between 30% and perhaps 35% or 40% since the batteries will need to be used as a buffer to an extent to provide proper/quick response to hitting the "gas" pedal. As others have said it will almost certainly have regen. capabilities (otherwise it would never hit 50mpg on gas like they say) so that energy will have to go back into the batteries. Remember, a small % charge on the Volts battery pack is equivalent to the entire usable energy available in the Prius battery pack so it will probably be capable of running around on elec. only just as much as a Prius even when not plugged in. Even a Prius runs out of battery juice at times and has no elec. mode available at that point.

Originally Posted by 04bonnie

For the price of this thing, it should do everything, and wash your dishes too! Not impressed, the Volt is over rated, sorry...don't see what all the hype is all about, it's practically taking over the news ticker, would like to hear other news besides the Volt.

Other than washing your dishes, what specifically do you want it to do so you WOULD be impressed?

[tamatt27]

The more I think about it, I'm not so sure the ICE would run at one constant RPM. I probably got that notion when thinking that they should use the HCCI in the Volt. It would make much more sense to vary the engine's RPM's in occordance with barrery load.

[miken123]

I hate to contribute to a 4 page long set of posts that really don't conclude anything but oh well.


The one fact we know is that the engine cannot directly drive the wheels.

The only way the wheels can get power is from the electric motor.

So where does the electric motor get power from? For the first ~40 miles and with a full charge, it would be the battery.

After that the engine has to kick on to provide power in some way to the electric motor that drives the wheels. This can happen in many ways that are dependant on how the vehicle is wired up. If the engine coupled to a generator only has lines to feed the battery then your only choice is to charge the battery to provide sufficient power to drive the electric motors with customer demand. If the engine/generator also has power lines going to the electric motors driving the vehicle itself, then it could simply provide power right to the electric motors as demanded by the drivers.

How the vehicle's architecture is set up i can't be sure...

Either way you're gonna have to generate enough power from the engine so that it can get converted to electrical power (at some loss of course) and then converted to electric motor torque output. If it's more efficient to do this with a direct power line to the motors than to go through the batteries and then to the motors --- Why wouldn't you want this to be the way it works???

Perception is a factor -- the engine will probably act like its responding to your foot pedal when it's really just ramping up speed to provide your electric motor with the power your immediately demanding.. this may make ppl 'think' their engine is driving their wheels direction but it's not.. is it more efficient than the engine to a transmission to the wheels (conventional)? I don't know but you can't have that or else you'd have just a two-mode hybrid.

[Evo69]

Jeez the whines are getting louder here...

[Ambalanche]

Originally Posted by tripowergto

Daniel Pund, Senior Editor, is an idiot media puppet. He probably thinks the VOLT concept is a coupe!

No doubt, and I didn't see him correct that mistake either. Like I've said many times before, there is no true journalism anymore, just members of the media with their own agendas.

[Ambalanche]

Originally Posted by 04bonnie

For the price of this thing, it should do everything, and wash your dishes too! Not impressed, the Volt is over rated, sorry...don't see what all the hype is all about, it's practically taking over the news ticker, would like to hear other news besides the Volt.

Wow! Where have I been? I must've missed something! When did GM release the price of the Volt?

[doppleganger]

Think about it this way; if the ICE could fully recharge the Volt's batteries then there would never really be any need to plug in the Volt at all.

That is not what the Volt was conceived to do, right? The goal, as I understand, is to use as little gasoline as possible, and the best way is to plug in the car to have enough juice to drive a typical daily commute of 40 miles or less. If you go beyond the 40 mi. range, the ICE provides juice so that you will not be stranded until the car can be plugged in again.

No suprises here. I still want one.

[A Bum In A Bus]

Edmunds is wrong, though this is not the first time for them, they are wrong...the small gasoline engine charges the battery pack, while the batteries power the vehicle. Since the battery will never completely recharge while driving, you can plug it in at night for a full charge and 40 mile capability. Should the battery completely discharge for whatever reason, the engine will keep you from being stranded. The engine was never intended to power the car for everyday driving. Sorry Edmunds relick your cow. Lutz was very clear on this when they introduced the Volt.