My understanding is that the gas engine will kick in when you have x% of charge left.

I want to be able to override this if I know I'm heading for a destination with a plug and the battery can go the distance. Let me drain the battery a little bit more than normal if I so choose since I'm almost home (maybe GPS could be integrated with this feature).

I can see being driven nuts having the gas kick in when I know I can make it on battery.

This idea come from my experience of driving an Insight 110k miles since 2001. In my normal driving the Insight battery is rarely drained more than 20%. The Insight programming is fixed, and I can't add 'boost' to use more of the electric motor and battery for my commute. So while the program is probably fine for some people it is not giving me maximum efficiency for my situation.

Awhile back, I posted that I wanted the range extender to only maintain the low level of charge, and not bring the batteries back up to a full charge, for the same reason you want to be able to draw the batteries all the way down (to minimize / eliminate gasoline usage). I believe this is what GM is going to do.

Unless you are fanatical about never using gasoline, I don't know how beneficial such a feature would be, and what risks there are to your vehicle system by drawing down the charge too low. I suspect that GM would try to make the vehicle as fool-proof as possible, because any vehicles seen on the side of the road would be very, very bad press.

I suspect that GM will set that threshold as low as is safe for the life of the battery.

I don't know anything about maintaining good charging capacity in Li-ion batteries, and there may be some better threshold for a 50+ mile a day commuter, who drive drive 70 most of the way, than a person who goes around town stopping frequently, and rarely getting above 40 mph. I am a big fan of personal customization (i.e. I'm a control freak), but I would recommend understanding the impacts to changing that threshold before doing so.

I thought that GM stated the battery charge would range from 80-40% when using the ICE, and only go up to 100% when plugged in at night, but never be allowed to go below 40% to ensure the battery can handle the 40 mile trip for it's full 10 year life.

Every layer of complexity, exponentially increases the number of things that can go wrong. AT LEAST INITIALLY, I'd vote for whatever method is the most bulletproof (Keep It Simple Sweetheart).
God Bless,
Tag

I thought that GM stated the battery charge would range from 80-40% when using the ICE, and only go up to 100% when plugged in at night, but never be allowed to go below 40% to ensure the battery can handle the 40 mile trip for it's full 10 year life.

I seem to recall it somewhat differently. GM stated the battery charge would range from 80-30% when using the ICE. :confused:

I also seem to recall GM stated the reason for this is battery life. Deep discharges and overcharging both have a negative effect upon battery life.

GM stated the battery charge would range from 80-30% when using the ICE. I also seem to recall GM stated the reason for this is battery life. Deep discharges and overcharging both have a negative effect upon battery life.

Yes the 80 - 30 is my understanding as well. The engine will kick in at 30% and maintain the charge between 25% and 35?% going by the E-flex pdf. Basically it will operate just like the Prius does now. When you get back home charge it up. You can always extend the range by driving slower & smoother.

Yes the 80 - 30 is my understanding as well. The engine will kick in at 30% and maintain the charge between 25% and 35?% going by the E-flex pdf. Basically it will operate just like the Prius does now. When you get back home charge it up. You can always extend the range by driving slower & smoother.

We apparently have the same understanding that the ICE would kick in when the battery is discharged to 30%. But, I had understood that once the ICE kicked in, it would charge the battery back up to 80%. Correct me if I am wrong!

One more thing. How is it the battery will fall to 25% when the ICE kicks in at 30%?

The E-flex design limits the generator to charge enough only to maintain about 30% of battery full charge. As Tagamet says, whatever is the most bullet proof and reliable battery state.

After all , it would be silly to use the generator to charge the battery then arrive home at 80%. You just eliminated the point of the Volt to begin with. Plug in grid charging, at low cost electric rates relative to the generator operation.

You only want the generator to do what is necessary to maintain optimum operation and self preservation. 10 year survival is the key.

My understanding (which may be wrong) is that the generator will crank out enough power to operate the electric motor(s) so that the vehicle functions as requested. As long as the battery stays on the lower end of the sweet spot, we'll arrive home with plenty of "room" left in the battery to be charged from the grid.
Exciting times!
God Bless

I'd say 'not likely'

The threshold set for the minimum charge on the battery is set for longevity. Would you really want to discharge your battery deeper, and cut months off of it's overall life? I didn't think so.

I will be in a different boat soon - I live ~12 miles from where I work now, but I'm buying a house that is ~25 miles from where I work. That means if I end up getting a Volt, and charge it up at home, I'm gonna end up using some gas on the way home. Doesn't bother me that much, as I'd still get astronomical fuel efficiency out of that ~10 miles of gas usage.

Then, who knows? Maybe there will be some advancements that will get the Volt more range! Maybe GM will determine that the battery can be discharged more with no adverse affect! Or maybe second generation batteries will be much better.

We'll have to wait and see, but if all works out, I will still buy a Volt.

We apparently have the same understanding that the ICE would kick in when the battery is discharged to 30%. But, I had understood that once the ICE kicked in, it would charge the battery back up to 80%. Correct me if I am wrong!

One more thing. How is it the battery will fall to 25% when the ICE kicks in at 30%?

At 30%SOC the car operates like a normal hybrid. Under hard acceleration the battery will need to supplement the generator. Conversely, when braking the charge could easily go over 30% by a small amount as well.

FrayAdjacent, I remember reading on one of the posts, that the range GM was shooting for would be 40 miles at the end of battery life. So you might get lucky and make it all the way home, at least in the early days.

At 30%SOC the car operates like a normal hybrid. Under hard acceleration the battery will need to supplement the generator. Conversely, when braking the charge could easily go over 30% by a small amount as well.

I don't think so as it relates to the italics and underlined above. The Volt will NEVER operate like a normal hybrid. It operates under electric power 100% of the time. The ICE powers a generator to charge the battery pack.

At least that is my understanding.

Just because you can "make it all the way on battery" doesnt mean that it will not harm the battery. As you drain a battery, its voltage starts to drop off, so using the last x% of the battery reduces cycle life. So no, you will have no control over that.

Another side of this question is... If the engine needs to run for 10 minutes of my 50 minute trip, then may I decide whether it is the first 10 minutes or the last? I think the answer is NO! you can't. We control freaks want to do this though and it will baffle and concern us why the machine chooses to do it a different way.
Here is one scenario... Cold morning, steep hill 5 miles followed by gradual downhill for 45 miles. I would prefer to run the ICE for the first 10 minutes to get up the hill and get some cabin heat going, then pretty much coast to the destination. The published response seems to be... Run the heater and climb the steep hill for 5 miles on battery power, then halfway down the other side of the hill, light the generator while the buggy is coasting. A non look ahead control system can never deal with these kinds of issues so leave it to the software guys to do a first approimation and take it as it comes or else hack the system and manipulate it for your own purposes. How do you think those guys ever got an EV-1 up to 179 MPH?

Another side of this question is... If the engine needs to run for 10 minutes of my 50 minute trip, then may I decide whether it is the first 10 minutes or the last? I think the answer is NO! you can't. We control freaks want to do this though and it will baffle and concern us why the machine chooses to do it a different way.
Here is one scenario... Cold morning, steep hill 5 miles followed by gradual downhill for 45 miles. I would prefer to run the ICE for the first 10 minutes to get up the hill and get some cabin heat going, then pretty much coast to the destination. The published response seems to be... Run the heater and climb the steep hill for 5 miles on battery power, then halfway down the other side of the hill, light the generator while the buggy is coasting. A non look ahead control system can never deal with these kinds of issues so leave it to the software guys to do a first approimation and take it as it comes or else hack the system and manipulate it for your own purposes. How do you think those guys ever got an EV-1 up to 179 MPH?

Wow, I think the operant term is "control freak". Even in the scenario you generated, the Volt would perform no better or worse than a parallel hybrid (read Toyota). You'd still get your initial gas-free miles, though probably a couple fewer. How about your poor neighbor who travels the OTHER direction to work? My point is that there's no way for engineers (currently) to spit out a car that fits every individual's needs. They do have to make compromises (I know, it's tough to accept). Eventually, I'm guessing cars will be able to "learn" from your driving routines and maximize themselves, but for now, I think we'll have to let them be in control.

Tag:

We programmers ALWAYS think we can do it better...............

:)

Yes TAG,
I am saying the same thing, we have to let the programmers do their best and see how that is. From a perfectionist (maybe just a picky person) point of view (mine), it would seem to make sense to give the battery a little boost under that heavy load even though it may not make a lot of difference. This perspective comes from having driven a battery car for 7 years and never had a gas engine to help out. I was thinking dav8tor might weigh in here being a pilot, since airplanes give you control over the smallest details of operation. Cars never did and probably won't (shouldn't?).

I am a little confused. I don't think the gas generator can charge the battery pack fast enough to keep up with the draw from the electric motor. For example to go the second 40 miles you will need to supply a total of 8kW (or however much you used) of energy to the battery pack in say less than an hour (40 minutes if your are going 60mph). I think when the generator runs it is powering the electric motor (like a diesel/electric train) and not really charging battery much if at all. The only way to drive all 600 mile without draining the battery too much is if the generator is running the electric motor and for that to work the generator must have the same power rating or larger as the electric motor. I think that is the case. If the electric motor is not drawing too much juice then the generator can charge the battery but in general it must be able to run the engine at maximum power drain. So after 640 mile the batteries will most likely not be charged much. To drive further you need more gas or need to plug in. So after the 40 battery miles the gas engine will need to run until you plug it back in. Furthermore is is more energy efficient to have the generator supply all the energy directly to the motor instead of storing in in the battery first and then sending it to the motor.

rjf13,
Check the FAQ. It addresses your question.

Thanks Tagamet. Actually I had already read the FAQ and it did not really make things clearer. So I guess what I am saying in response to the original thread. No you can not choose when the gas engine kicks in. The gas engine will always run after the first 40 miles until it is plugged in.

rjf13:

One small but important clarification to your post.

The ICE will kick in and run when the SOC of the battery pack is at 30%. It is not really related to the range. If I am sitting in my driveway and I have the air conditioner on, all the lights on, and the radio playing, but I have not moved an inch, The ICE could still kick on at some point....

rjf13:

One small but important clarification to your post.

The ICE will kick in and run when the SOC of the battery pack is at 30%. It is not really related to the range. If I am sitting in my driveway and I have the air conditioner on, all the lights on, and the radio playing, but I have not moved an inch, The ICE could still kick on at some point....

And I'd be moved to point at you and laugh. (just kidding). I was just about to point that out too.

rjf13:

One small but important clarification to your post.

The ICE will kick in and run when the SOC of the battery pack is at 30%. It is not really related to the range. If I am sitting in my driveway and I have the air conditioner on, all the lights on, and the radio playing, but I have not moved an inch, The ICE could still kick on at some point....

Thanks Jim, That would have been a better way to state it. If you are sitting in your driveway you would be better off plugging in :). I can not think of a situation where you would want to charge the batteries from the gas motor. It is more efficient to power the motor directly then to charge the battery and then use that energy from the battery.

So I assume you have never been thrown out of the house by your wife???? Not that I would ever admit to that having happened to me, since she is a rare and gentile flower and the light of my life....

I guess you would still drive by and laugh at me, huh?

So I assume you have never been thrown out of the house by your wife???? Not that I would ever admit to that having happened to me, since she is a rare and gentile flower and the light of my life....

I guess you would still drive by and laugh at me, huh?

Actually I would honk. :rolleyes: What I am saying is that even if no plug is available it would be more efficient to have he gas generator power the engine instead of charging the batteries, in most cases.

Yes, it is a common technique to improve battery life by reducing the range of SOC. Toyota seems to be having zero problems with the Prius battery by shallow cycling it from about 40-80%... the stress is at the extremes of discharge and full-charge. Given the battery pack is such an expensive component and they are concerned about durability from a customer satisfaction and warranty standpoint, I don't see how they would want drivers to have the ability to play with the algorithms to maximize the AER at the probable expense of battery durability. After a Volt's warranty period expires, then maybe folks can hack into the controls and play with it.. but by then they probably will have progressively improved the batteries and efficiencies to increase range.. or folks will come up with AER-extending kits for the Volt (similar to todays' companies who have created PHEV conversion kits for the Prius and Escape)

An open standards interface for the battery and control system (or a GM designed and sold
"AER booster" battery) which would allow AER-extension would be a useful feature to have. If folks want to spend the money and don't mind losing the trunk space, let them plug in more batteries to go beyond 40 miles.

I really, really want this too. I realize there will be a warrantee issue with this and battery concerns to consider. I want it so much because my driving will only equate to about 3500 e-miles/year if only 8KWh can be utilized. Shortening the battery cycle life by discharge to 20% is a non-issue for me. Resides, my understanding is that discharge to 20% is not harsh on she drafty. I believe it is more of a power and performance issue. Remember, the battery will be relied on for supplemental power, even after the germinator kicks in. The Volt will need to perform even in generator mode while on climbs, so if you start a mountain pass with the generator on you will still need the power to pass at the top. I think this 46 more the reason for the 30% floor on discharge than battery life. Living in South Florida, this is a non-issue for me.

Furthermore, on occasion I would like to be able to override the charge limit of 80%. I would do this for days that I know my driving will be more than 80% will provide. I do believe the 80% limit is to extend battery life. Lithium Ion batteries do lose life when stored at or near full capacity , which gets worse the warmer the ambient temperature is. I believe charging to 90 or 95% 3-5 times per month will have minimal impact on cycle life, and certainly not enough to affect my usable battery life given my current driving pattern.

Allowing 20% to 95% cycling will allow me to get 1000 - 1500 more e-miles per year that I would never otherwise get. If someone pays for the battery, then they should be able to safely use as they see fit.

Additionally, even if I drove 40+ miles/day, I would want to be able to set the charge cycle limits. Batteries have improved tremendously over the last 7 years and I am comfortable that they will continue to improve. So, if I could get 110,000 miles in 6-7 years I would opt for it.

There is no way the Volt could get 40 miles out of 8 kWh! My understanding is this:
The overnight charge WILL charge the battery fully, to 100%. Then the battery is discharged to 30% before the ICE kicks in. That is 11.2 kWh. about 4 miles per kWh. In real driving conditions you will likely get only three miles per kWh, so the range will be about 30 miles. When the ICE is on, it provides electricity to the motor, and any extra will recharge the battery. If the battery gets to 80%, then the ICE is turned off.

KariK, the Volt may end up with the scenario you mention but that was not what the last words that I've seen have said. Their intent was expressed as charge to 80% and discharge to 30% before genset kicks in. 8KWh seemed a little light for 40 miles but that's why they are working so hard to reduce Cd and auxiliary power use. It also probably means 55mph for highway driving. Maybe it will require 85-25 to make it happen, but it would be very surprising for GM to claim 10yr battery life and default charging to 100%.

I think rjf13 makes some good points. What happens to performance once the batteries are depleted? At this point the batteries will be charging from the generator. However, this takes time. In the mean time any charging progress may be lost if the batteries are repeatedly called upon to support the efforts of the generator which - as rjf13 points out - is now the primary source of propulsion energy. If a driver is particularly aggressive, the charging progress may not be able to keep up with repeated demands for motor support (hard acceleration). SOC must be maintained at a reasonable level to protect battery life....so the probability is that eventually performance is effectively going to be limited by the capacity of the generator (because a cap will eventually be put on battery discharge)

Think this through! Does this mean that acceleration is going to be faster early in the day (when running purely on batteries) than later in the day (when running with depleted batteries, discharge has been capped and power is limited by the capacity of the generator)? Does this mean that before pulling out to overtake I will have to mentally consider the SOC of my batteries (as well as the usual considerations of space, speed etc)? No way! It is vital for drivability that acceleration is consistent irrespective of where the power is being drawn from.

The only way to reconcile these factors is to put a cap on motor power that is less than or equal to what the generator alone can provide. So that would be 53kW? Then GM would not need to worry about performance inconsistency. But, in this case, do the published acceleration figures bear scrutiny?

I'm very interested in the 53kW generator but can't find much information on it. Does anyone have information regarding this unit?

Chris,
This question was asked directly of Dr Weber at the Voltnation, and he assured us that there would be no dimished capacity to perform regardless of whether the Volt was at full charge or in charging mode.