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Discussion Starter #1
Guys I have a question for the experienced in this forum. I've had my Bolt for about a fortnight now. My daily commute is about 60 miles and then some for shopping etc. So maybe about 70~80 miles daily. I tend to put it on the charger every evening so it's fully charged in the AM. My question: Is it OK to charge it to full everyday? Will it impact battery life in the long run, you know how they say that li-ion batteries should not be charged to 100%. Also, I keep it plugged in all night. Let me know if I need to change any of these practices please?
 

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One hundred percent is not 100%. Just as battery manufacturers won't let you fully drain the battery, you can't actually charge all the way to Full. Modern battery tech keeps a cushion at both ends of the charge-discharge cycle. Do whatever makes you most comfortable. The battery will take care of itself.
 

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There's been a lot of discussion and investigation on this, indications are that there is no hidden reserve on the Bolt.

But that just means we have a better situation - most people can stick it in hilltop reserve, forget about it and always have enough range. But for those occasional long trips, or for those few people who really need every mile you can charge to 100% - best of both worlds. Agree with NY-Rob, just put on the HR and you'll be wearing a belt and suspenders.
 

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One hundred percent is not 100%. Just as battery manufacturers won't let you fully drain the battery, you can't actually charge all the way to Full. Modern battery tech keeps a cushion at both ends of the charge-discharge cycle. Do whatever makes you most comfortable. The battery will take care of itself.
what is your source for this information - I'd love to hear this from Chevy. to date I do not believe this has been confirmed. And all data regarding LiON batteries is that charging them to 100% on every charge cycle does decrease longevity.

can you provide any references backing this assertion up with regards to the Bolt and it's LG battery system?
 

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Discussion Starter #7
Thank you guys! Traditional wisdom dictates that Li-ion don't fare that well when charged to 100% frequently. I will try hilltop reserve and see how that fares. Again, we don't really "know" how these high quality li-ion batteries in cars are supposed to behave, so to err on the side of caution makes sense. Any additional information on this (especially from proper sources) is greatly appreciated over time. If I find out more, I will be sure to update you guys as well.
 

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Charge to what you feel comfortable with. I charge to 100% since in the winter now, I average 190 miles and I have a 100 mile commute. Should there be traffic on I-5 (likely) and it's cold, I need that extra range to keep me warm. There's also detours when I want to drive around the traffic using slower roads but longer distance. Having 90 miles of reserve is nice.

In the summer when I hopefully hit 238+ miles, I may switch to 90% (hilltop reserve) to maximize battery pack life.
 

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GM says to plug it in to charge it to 100% with no restrictions or warnings (but they do allow for a bit more degradation than some before a warranty claim can be made).
Former and current LEAF owners are often horrified at the thought.
I don't know of a single EV that allows for true 0% to 100% use of the battery, and can't imagine that GM would decide it was prudent to do so.

We have plugged in our Fit EV virtually every night and charged to 100% with no noticeable loss in range (4 years and about 40K miles). Only one or two Fit EV owners have reported any apparent degradation (and those only a very small amount). Some have 70K+ miles. Contrast that with LEAF owners that religiously charge to no more than 70% unless absolutely necessary, only do that moments before their trip to avoid having the battery at a high SOC, monitor battery temps with LEAFSpy to make sure it never overheats. And then find they are dropping bars (more on the new 30 kWh pack than the lizard 24 kWh).

The jury is still out on the Bolt, but I see no reason to assume that the people on this forum know better than the engineers at GM. It's coming up on a year on the market and I have heard not a single report of battery degradation (other temporary range loss due to cold weather). Visit a LEAF forum and you will find a much different song being sung by owners with cars <1 yr old.
 

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I met an uber driver at a dc fast charge station who talked to me about my snow tires. He had gotten his Bolt in march and has does 58,000 kms on it. Says he charges at the dc fast charge everytime he drives someone to the airport. And clearly must charge it every night. When I asked him whether hes seen any range loss, he indicated no. I realize this is anecdotal but it was from a Bolt owner. He did show me his uber app :)

IBB
 

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:eek:I'm not convinced charging to 100% or whatever the Bolt will allow is a bad thing. With a full charge, I can normally go a full week between charges. With a three year lease, my Bolt won't encounter as many charges and depletions that most will. Chevy built it, they hold the warranty, and I feel confident in three years my Bolt will still average 238 miles range on a full charge. Although home charging is a breeze, time and motion studies encourage less time and motion.
 

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I had a very early Gen I Volt and did a full charge/discharge twice per day. After about 80k miles, I'd lost about 15% battery capacity, but the car still nearly achieved the EPA range of 36 miles. LG later made some battery chemistry improvements, so this is worst case for the Volt.

Battery chemistry for the Bolt is likely different still, however GM's battery testing and validation is just as robust. I'm quite confident in the Bolt's battery, regardless of usage and charge scenarios.

I'm leasing my Bolt but want to know that the battery will have full capacity at year three to make the occasional 200-ish mile road trip. For that reason, I'm using both HTR and Priority Charging to make sure that the battery stays in its "happy place" most of the time. As others have said, I do a full charge if embarking on a trip that will require >100 miles on a single charge.

Another thing to remember with Li batteries, is that it is probably worse to keep the battery at a low SOC than it is at a high SOC. That's why I think Priority charging is so important. Especially in cold temperature, it's best to have the car plugged in and charging (and battery conditioning), even at peak energy rates, if necessary to get the battery back up to 40% SOC.
 

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Use of acronyms

I have a suggestion that it would be nice if those of us who are familiar with acronyms would define acronyms at first use in our text. While I may know the meaning of such acronyms as PEV, BEV, SOC, newcomers to the site may not know them and would feel unwelcome because we are essentially speaking in code by use of acronyms. Personally, I try to avoid the use of acronyms altogether. Its not too difficult to write out the English words, and it is more helpful for the community as a whole, especially neophytes who are the proud owners of a new Chevy Bolt EV.
 

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The issue here seems to be that people think that showing "100%" on a dashboard display means that the batteries are charged to 100% of their potential. Not true.

The dashboard displays simply show you the percentage of the state of charge which the Chevy engineers chose as the upper limit on the voltage to which you are allowed to charge the batteries. It is not the physical limit of the cells maximum charge capability.

It is definitely Not the maximum possible charge-level for the cells - that would be extremely stupid engineering.
 

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The higher the state of charge, and the higher the temperature, the more parasitic reactions happen in the battery, building the SEI (Solid Electrolyte Interface) layer on the anode. It is well known and undisputed that higher states of charge cause more rapid capacity degradation in all production lithium ion batteries, the Bolt is no different or special in this regard it is an unsolved sub-optimal technical outcome. Whether it's worth worrying about is up to the individual owner. In cold weather, the bonus of colder average storage temperature slows down these chemical reactions. GM has a good track record with conservative battery management on the Volt, which many by extension apply to their future Bolt predictions. You are on the tip of the sword vis-a-vis the Bolt, only the future holds the answers you seek.

Regarding TLA's, while some consider them elitist, it has been long held that it is more efficient for daily communication, even while considering the constant stream of FNG's seeking clarity. The industry has adopted the terminology and the associated shorthand, it is unlikely to change. If someone fails to ask a question or use their search faculties to illuminate the subject or dispel confusion, the fault rests squarely with them, IMO. I do try to spell out the less commonly used terms, personally.
 

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It is definitely Not the maximum possible charge-level for the cells - that would be extremely stupid engineering.
We just discussed this again in the answers above. We do NOT know if there is a hidden reserve but the best information we have indicates there IS NOT.

Not having a reserve is not 'extremely stupid engineering' - are you a GM battery engineer? They've done tens/hundreds of thousands of hours of testing at their battery testing lab, all we know is that they are comfortable setting a degradation specification and range warrantee (notably with a big caveat in the owners manual). There is a lot of babysitting with these cells, it easily could be the case that they give us approximately the full physical capacity knowing that in real world application the control electronics and thermal management are adequate to keep it within spec. And also people typically drive it off the next day and run that battery right down - it could be that with these cells it's not so much charging to capacity but rather keeping it at capacity (they have guidelines in the manual for long range storage.

Everything I've heard about LiIon battery care

  • They do like to be used, so feel free to drive the car and push the battery up and down
  • Generally LiIion likes to be 20%-80% or conservatively 30%-70%, however 10%-90% is probably about as equal benefit
  • They are really sensitive to temperature (hence the thermal management)
  • Cell leveling, according to this paper cell leveling (which occurs at end of charge) is beneficial for 'significant' pack lifetime extension*
So while I try to keep 30%-70% I do charge up to 90% at least once a week to allow the leveling algorithm to run. Further, running it up to 100% occasionally probably doesn't hurt either.

* Edit: I have access to IEEE papers but won't bother reading it, but I'd guess the reason why leveling is important because different cells drain at different rates, so for example for a fast drain cell you'd like to utilize that less than the fast drain, thus improving the overall longevity. However I'd also assume that the discharge rate is relatively constant over the lifetime of the cell and that the important wear leveling run is the first one run at the factory, so it's perhaps not that important to constantly be running this algorithm
 

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We just discussed this again in the answers above. We do NOT know if there is a hidden reserve but the best information we have indicates there IS NOT.
Please link to this "best information". All I've seen is speculation.

Non sunt multiplicanda entia sine necessitate

The simplest explanation is that GM has continued to do what they (and other manufacturers) have considered best practice.
 

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Please link to this "best information". All I've seen is speculation.
"Search" the forums, there have been many posts about it, specifically estimations given the mass of material from the UBS teardown, in addition to road tests run from 100% to 0%. These estimations are the "best information" I've seen.

Speculation - yes that's what I'm saying isn't it? I'm not citing proof or hard evidence so don't get on that track please. How about this? "The "best speculation" I've seen on this board indicate there is no reserve." Hopefully that's clear enough for the high standards of internet forums.
 

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We will start to see how the battery holds up pretty soon. I just fully charged my battery and didn't notice any battery degradation, however it could be a few percent and I don't think I would be able to know. I am approaching 18,000 miles. There is a youtuber that has over 30,000 miles and hasn't noticed any degradation as well. As soon as a few of us long commuters put some serious miles on our Bolt's, the battery life will soon be known. I expect that I will put on about 25,000 to 30,000 miles a year on the Bolt. So I will find out in a few years how the battery holds up...


I do use hilltop reserve and usually always have 25% plus of my battery remaining when I charge. So I usually charge from 30% to the 86% (sometimes hilltop does above this) almost every day of the work week.
 

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Discussion Starter #20
Great feedback and opinions! I am going to try HillTop mode and see how things go. But generally with Li-ion batteries the way its not good to keep them at 100%, it's actually worst to let them run all the way down and then charge them up too! Number of charge cycles also factor in at that point. I guess these are much more robust batteries, especially with the liquid cooling/heating that Chevy put in place. My takeaway from this is "do what you think works for you"! Thanks to everyone for the valuable information and experiences shared!
 
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