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With GM’s decision to discontinue the Volt I had a couple questions for the forum relative to the expected battery life of a Volt. I usually keep my cars 10-15 years and have been averaging about 7k miles a year on my Volt in the two years I have owned it. So based on that it would take me about 14 years to get to 100k miles. I know GM guarantees the battery for 100k miles (not sure if there is a time limit on that). Anyway here are my questions.

1. Is there any data on how long we can expect our batteries to last? After 14 years I expect it will be difficult to obtain a replacement battery, but hopefully not impossible. Volts have been on the road for close to a decade now so hopefully there is some data available to base an estimate on.

2. As the battery degrades I assume our EV range gets shorter. Is there a cutoff when the car will not longer function as a EV but as a hybrid only? Can the car even function as a hybrid with a battery that is so degraded that it will no longer operate as a EV?

3. Can the batteries be reconditioned after they age and show degradation? I assume not but thought I’d ask.

Thanks. -Ed
 

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There are plenty of answers about these topics in the forum; if you do word searches you will find more than you want probably on the topics.

But in summary, the experience on the battery packs has been that there’s been very few failures, and little in terms of degradation, even at more than 150,000 miles.

Several volts are well past 200,000 miles and still functioning well on the battery.

The Volt has a built-in buffer — both at the top and the bottom — the “empty” and “full” parts of the battery — to keep the battery more in the middle of its capacity, which is what lithium ion batteries like. That plus the elaborate liquid cooling and temperature monitoring and control system for the battery leads to reliability and longevity. Only Tesla and GM really utilize this battery preservation process to that extent.

So there’s very little to worry about with respect to the longevity and reliability of the battery pack.

If after many years and hundreds of thousands of miles the Volt may eventually act more like a typical Prius type hybrid, but it will still have some reduced pure EV range.

It should be possible to obtain a replacement battery, but after many years it may not be worth putting in the car at that point. I do think there will be aftermarket replacement battery packs available for EV’s, just as other aftermarket engines and other things are available for older gasoline cars today.

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im only 1 user case but my 2012 Volt that I just sold with 136k miles definitely had battery loss. For many years I was getting around 37 miles this time of year in Michigan where its colder and now I was getting 25 miles tops. Loving my 2019 Volt though....
 

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I have been leaving a few miles on the battery at night - target about 5 or less. I guess not necessary?

I assume stepping up to Level 2 charging doesn't hurt, yes? I just got my level 2 charger.
 

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Mile wise the batteries in California have a 150,000 mile warranty. Sparkie has over 440,000 miles and while he thought it might have had a battery problem towards the end it turned out to be something else. I've read that GM says you can get 6,000 charges and in another 8,000 charges I don't know where these came from. I don't think we don't know how low a battery can go (range wise) before it throws a code. Uneven cells are another thing. A battery is a battery and there is no way to tell when something might happen to it before its time. We don't know what advancements will come in the future or if battery and accompanying electronics will come down in price and size such that putting in an aftermarket battery will be child's play that any 16 year old interested in cars will be able to handle with ease. I tend to keep my cars for two, three or four decades so will look forward to this question will interest.
 

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I have been leaving a few miles on the battery at night - target about 5 or less. I guess not necessary?

I assume stepping up to Level 2 charging doesn't hurt, yes? I just got my level 2 charger.
No Level 2 will not hurt is much faster to fill and is very slightly more efficient than level 1.


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I have been leaving a few miles on the battery at night - target about 5 or less. I guess not necessary?
I do the same. Leaving a bit on the bottom of the battery certainly can’t hurt the longevity and can only help but how much I don’t know, may not really be necessary given the built in buffer.


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After a time, the issue becomes: is GM using the same battery tech? If GM moves to the skate board configuration that seems to be the rage, then will they choose to stockpile some old Volt batteries and let them sit until needed? From personal experience, these batteries don't store well.

In 2009 I managed to score a replacement battery on my Insight just before the 10/100K warranty expired. The problem is that Honda had discontinued the Insight in 2006 so my replacement battery had been sitting on a shelf somewhere for years. It lasted less than two years before I got yet another free replacement. When that third battery started to crap out, I added a grid charger so that I could recondition/balance the battery periodically and limped along until I got the Volt.

The good news is that small third party companies filled the gap for the Insight which has a much lower number of units on the road. Someone will step in to fill the same niche for the much larger Volt community if the need presents itself, but this issue of potentially stale batteries from GM is something to keep an eye on in the coming years.
 

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First, this is a great question, however the first Volts came out 8 years ago so we're just beginning to get real use data points.

Three factors will result in Li-Ion degradation on our Volts, excluding manufacturing defects.
1. Charge/discharge cycles.
2. Time.
3. Temperature.

For the first factor, Chevy has tested the battery pack to 200,000 miles without failures. So in this it appears to be good. I personally drive 20k miles a year and ~80% of this is on battery. Therefore if I keep it, at year 10 it will have 160k on the battery / 40k on the engine. At year 15 I'd have 240k on the battery / 60k on the engine.

For time the first units are just reaching 8 years, so we'll see.

For temperature, the Volt's thermal management system handles this well so it shouldn't be an issue.

Regarding battery replacement, I wouldn't count on them being available more than 8 years after the end date, and those replacements may have been sitting in a warehouse for a long time, and therefore affected by the "time" factor.
 

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Who knows what technology will be available when these cars are 15-20 years old. Hopefully some aftermarket company will offer a solution, like maybe even a super capacitor package to drop in place of the battery. Even if it is something that does not have a lot of AER, but keeps the car running at full performance without the battery, it would be interesting. I think there will be a lot of very old Volts someday that have engines that are still in excellent, nearly-new condition.
 

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I know GM guarantees the battery for 100k miles (not sure if there is a time limit on that).
The warranty is for 8 years / 100,000 miles whichever comes first.
 

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The warranty is for 8 years / 100,000 miles whichever comes first.
I believe that in California the Voltec system warranty is 10 years / 150,000 miles.
 

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2. As the battery degrades I assume our EV range gets shorter. Is there a cutoff when the car will not longer function as a EV but as a hybrid only? Can the car even function as a hybrid with a battery that is so degraded that it will no longer operate as a EV?
I suspect there’s a distinction between a Volt battery that has "lost some of its oomph" over time, and one that has a repairable or irreparable problem, such as unbalanced cells.

GM restricts Electric Mode driving to the use of a relatively fixed percentage window of the full battery capacity. Both Generations also have a bit of accessible space at the top (allows a small amount of regen to occur when the battery is fully charged), and another small buffer between the "switch to gas" and the "hard floor" state of charge.

If the battery degrades over time and the "usable window" remains the fixed percentage, then the kWh Used in a full charge will drop, reflected by the drop in range. But for one reason, I don’t know why you couldn’t drive your Volt in Electric Mode with an aging battery whose "usable window" contained only 1 kWh of grid power.

The 8 yr/100,000 mile battery warranty says the Gen 1 battery may degrade as little as 10% to as much as 30% of capacity over the warranty period, with the corresponding numbers for the Gen 2 Volt and Bolt at 10% and 40%.

Many owners are quick to call out "battery degradation" without taking those limits into consideration. Where is the 2013 Volt owner who gets only 7.5 kWh Used (down from 10.7) from a full charge, or a Gen 2 Volt owner with a 8.5 kWh Used reading who is then told, "your battery is within acceptable degradation limits?" Most acknowledged battery problems occur long before the kWh Used has dropped that far, and seem to be related to problems other than old age.

Note, however, that "acceptable" degradation over time reduces not only your Volt’s ev range and kWh Used per charge, but also the amount of power that is being maintained in the fully depleted battery buffer. That reduction could be critical.

When driving with a fully depleted battery, the Volt retains a ~5% buffer of "borrowable" power between the "switch to gas" and the "hard floor" state of charge. Under various driving conditions, the system may "borrow" some power to maintain performance, after which the generator will run to recharge it. Mountain Mode merely sets the "switch to gas" point higher, enlarging the "borrowable" power buffer for use when driving up mountains.

The battery’s usable power is also used for one particular task: starting the engine. The smaller motor is the car’s "starter" motor. Battery power spins MGA, MGA spins the engine, and, once running, the engine spins MGA as a generator. When the Volt battery is fully depleted, the 5% buffer is the source of power for the car’s starter motor.

The quantity of power in a 5% buffer of a degraded battery could be important. If you pull into a parking spot with the engine running, the generator might be recharging some power that has been "borrowed." If you turn off the car while the engine is still running (i.e., the buffer is less than "full"), the state of charge is still below the "switch to gas" soc. When you then Start the car, MGA draws some power from this buffer to start the engine.

The normal 5% buffer holds less than 1 kWh of usable power. An "acceptable" degree of degradation reduces that even more. Turning off the car while the engine is still running leaves even less usable power in that buffer. It seems possible that the amount of power used to start the car with a degraded battery may drop the battery soc so close to the "hard floor" soc that, to protect the battery, the computer will trigger a Propulsion Power Reduced episode, giving the generator time to recharge the buffer before allowing the car to operate normally.

I suspect that some of the reported PPR problems currently being experienced in older Volts are not cell balancing problems, but "battery getting older, losing some oomph" problems. Perhaps if drivers of such cars would, when reaching an intermediate stop on their route, wait to turn off the engine until after it has stopped running (indicating a full buffer), that small change might enable a battery that has lost some oomph to restart the car and be driven with no PPR episodes.

IOW, it might be possible for you to drive a Volt in Electric Mode almost forever as the battery slowly degrades over time (loss of usable kWh in the usable window will produce loss of range), but at a certain point of degradation, the reduction in the amount of usable power in the "fully depleted battery buffer" will increasingly trigger PPR episodes during the trips - at first, when you turn off, then turn on the car, and eventually when the demand for power to maintain performance in normal driving conditions is too much for the buffer to supply.
 

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I too buy and hold. Your answers are in the posts above.

Summary, don't worry about it.

My 2011 is going strong with 97+k miles on it. I may have lost about 2 miles range or so. Hard to say.
 

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My2018 started out at 53 miles EV full charge. It is now averaging around 38. Is this normal? If it is - the joke's on me I guess.
 

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My2018 started out at 53 miles EV full charge. It is now averaging around 38. Is this normal? If it is - the joke's on me I guess.
If you are running the heater a lot now and weren’t before that alone would be the reason. 38 in the summer or just when it’s cold?


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my 2016 new showed 14.2 kw when gas kicked in
110,000 km with 84% electric so 92,000 km on battery 2600 charging -40 to +22c parked outside
now shows 13.8 kw when gas kicks in so a 3% loss
40% warranty is down to 8.5kw i think
 

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If you are running the heater a lot now and weren’t before that alone would be the reason. 38 in the summer or just when it’s cold?


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Even if you are not running the heater, if it is cold outside the car will sap some battery power to heat itself to help prevent battery degredation. If it’s really cold, you will get ERDTT (engine running due to temperature)

When I first bought my volt I watched all the numbers and tried all sorts of things to try to eek out more mileage. Now I just hop in and drive and never go to the energy screen. I can’t tell you how many miles I’m achieving on a single charge.
 

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Even if you are not running the heater, if it is cold outside the car will sap some battery power to heat itself to help prevent battery degredation. If it’s really cold, you will get ERDTT (engine running due to temperature)

When I first bought my volt I watched all the numbers and tried all sorts of things to try to eek out more mileage. Now I just hop in and drive and never go to the energy screen. I can’t tell you how many miles I’m achieving on a single charge.
i have seen heater take 40% of battery power
 

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i have seen heater take 40% of battery power
It’s not only the heater. Cold batteries just don’t produce as much juice. Just take your fully charged cellphone outside and expose it to the freezing cold. In a very short time you will see battery life drop. Then bring it back inside or put it in your pocket and you will see battery levels increase.
 
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