The Volt will turn on the generator...

 

I heard those batteries were ones GM used in their lab for testing. Who knows what they did to them before using them as backup power.

 

You will be unlikely to experience a dead battery. More likely, at some point after the car is say 15 or 20 years old your all electric range will be much less than it is today. That means your ICE will run more often.

 

At 3000 Charge/Discharge cycles you most likely will have 30% degradation say in 8 to 10 years. Then, say keep it for two more years when you can no longer accept electric range loss. I get 52 mi driving nicely; about 32 when I've to beat that BMW kid So, I'm OK with 40% hit right away for the sake of fun. You may decide when that's OK for you. Power-loss no - Energy retention loss - yes.
Like someone else mentioned on the board - 600 k on electric drive + 200 k on gas engine + battery swap. I say ... 200k on the battery and 100k on the gas - run the battery to the ground - leather smells bad at 300k miles. Recycle the car.

OH, the thermal management and overly cautious approah of LG Chem makes these batteries really really good.
This ought to be the prime reason to prefer the Gen 1 Volt over Gen 2 - the extreme design. Gen 2 - extremely efficient design i.e. cost efficiency - lower battery-craftsmanship. But I'll keep Gen 1 just for the beautiful / non-ugly tail lights.

 

You would know immediately if the battery goes dead, because the Volt will show some codes and refuse to drive.
Otherwise, the battery will eventually, (we think), start to lose some of it's range.

Chevrolet, at first, was estimating about 10-12 years of "useful" life. They later, after more accelerated testing, said it may easily get 15 or more years of "useful" life. (still at or above 70% of it's range intact)

 

As others have said, it probably won't happen unless you keep the car a very long time. Our resident GM contact had told us that when it reaches replacement levels, the car will set a code that says the battery internal resistance had reached the threshold.

If this happens within the first eight years or hundred thousand miles, GM will give you a new battery pack (ten years and 150k miles for some cars sold in CARB states.)

 

So, what else will happen when the code is set saying that the battery internal resistance has reached the threshold? Will the car still function as it normally does, allowing the owner to continue to utilize the CD and CS modes? Or will the owner then be faced with a bricked car?

 

Even then the cost of a replacement pack **WITH TRADE IN** is fairly reasonable IMO.

 

Based on everything we know and have been told I doubt this is a problem worth worrying about. You will need to own your Volt for a very long time, then you'll probably see a gradual loss of electric range and at some point it could drop to such a state that a new battery is needed. By then a new replacement battery could cost just less than a traditional ICE valve job.

I wouldn't worry about this.

 

I'm hoping that when such a time approaches, there will be 3rd party suppliers ready to swap out for a bigger battery and upgrade the BMS to improve the range! Seems plausible this will happen?

 

There are owners that have driven over 75k EV miles and 240k miles overall that have stated they have experienced no discernible battery capacity loss. I think literally the HV battery will last until the wheels far off the Volt. And even then, the battery will still probably be good enough to use for energy storage applications.

 

The li-ion battery and thermal management system in the Volt are so well designed that there's a very good possibility of the battery being usable for the lifetime of the car.

Others like the Tesla Model S and Ford Focus EV also have great battery designs with thermal management systems.

Note that the Nissan Leaf does not yet have a battery thermal management system except for a heater that's used in the winter time, and because of this many Leaf owners, even those new to the Leaf within the last year, are unfortunately experiencing noticeable battery degradation.

 

No one knows......

 

.. when they "are no longer powerful enough to propel the car", I am left asking:

WHEN IS THAT AND HOW WILL I KNOW???

...

as others have said Dan, you may never know. you keep your cars for 10-11 years, if you go through 300 full discharge/charge cycles a year, that would be a lot, you will want to get through 3000 full discharge/charge cycles. There are 2011 volt owners who already have 2400 full charge /discharge cycles and report no noticeable change in battery capacity. (yes some owners are getting 2 cycles a day 6 days a week)
As has been mentioned, there are a couple of failure messages that a degraded battery could throw, and the car would go into limp along mode or not run, we don't know. I prefer to look at it this way though:
If you battery loses half its capacity, it will drive like a new C-Max energy. 20 miles per charge. IF it loses 75% of its capacity it will drive like a new Plug-in Prius- 12 miles per charge before the generator kicks in. you would NEVER replace a degraded battery under these conditions: a 12 year old car with 170,000 miles would be worth what $4,000? would you spend $2000 or $3000 on a battery, or just keep driving with your range extender engine?