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I've done a lot of googling and reading on the subject and I agree, as it relates to the Bolt, there's simply insufficient Bolt data to come to a fact based conclusion regarding best charging practices. However, there's plenty of data on lithium batteries in general. These are my conclusions I'd love to hear other comments.

Chevy is going to tell you to charge to 100% if they don't the obvious follow up questions gets convoluted because on one hand their marketing specs are 238 miles, but if the recommendation is to charge to less than 100%, well you see the rabbit hole they don't want to go into. Additionally, Chevy added the option of Hill-Top reserve. Why even go to the trouble of engineering this feature? Much simpler to say if battery is at capacity then there is no regenerative breaking. That seems obvious and sufficient. So why go through the trouble to design this feature? I don't believe for a second that this feature was intended for the purpose advertised. Without any direct proof, I believe that this started out as something different and when Markeiting got a hold of it they changed the name for apparent reasons. I've been in too many marketing meetings with too many products not ready to ship or inferior to the competition and know that straight language is not in marketing mentality. If organization has a device that runs slower than the competition then Marketing will advertise it as "the fastest". I believe that Chevy knows that charging the battery to 100% all the time is not good for lithium batteries. But I don't expect that Checy will say outright, if you think about it they can't. why? The rabbit hole . . .

The accepted treatment of lithium batteries is to not overcharge, to not discharge them below a specific voltage range and to store them (I'll say) at a mid-voltage range. I don't worry to much about the Bolt battery. I typically charge it when it goes to about 30% and charge it to about 84%. I have a 2017 Bolt Premier (blue and I love it) and it the battery now has a capacity of 57 kWh as measure with an OBD2. I charge it to about 83% when I plug it in. I typically charge once a week on an L2 so that gives you and idea of how few miles I drive typically. If I know am going on a long trip then I charge it to full and schedule the charge so that it's finished as am ready to leave. The reason I bought the EV Juice Box was because it allowed the configuring of the input current how much "juice" to give the Bolt.

BTW this is an opinion based on personal experience. I have not evidence to support the above statements other than past personal experience not related directly to the Bolt.
 

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I restrict my charging to 85-ish %. But even when I charge to 100% I verified the one pedal driving still works the same. So 100% is not really 100%. This is a 2020 LT.
 

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"Does anyone worry about their cell phone battery this way? "

Yes! I only discharge to about 20%, and take it off the charger at about 90%, if I'm around while it's charging.

I typically get 4-5 years out of a cell-phone battery. I tend to keep a smart phone until apps stop working because it's OS is so "old". I retired my Samsung Note 3 after seven years. It's now a display for my solar PV system controller.
iPhones have a program for that for optimal charging.Available for a few months.
 

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Discussion Starter #44
Thanks NewsCoulomb I believe you are the first to give an approximate % degradation. I been following you for a long time on you tube. Between your videos and post on here is what lead me to purchasing my bolt I thank you and all the crew here for your/their input.
My history with battery powered/assisted vehicles. My first was a 2007 Nissan Altima Hybrid it would run on battery power when under 25 mph and got about 5 miles if you were lucky. At around 130k miles traded it for a 2013 Hyundai Sonata hybrid this took me to 194k then the hybrid system would shut down and say pull over and stop driving with research found that Hyundai had no idea what was causing this issue so February if this year I treaded it for a 2019 Toyota Camry hybrid LE I went with particular vehicle for 2 reason 1 was price 2 it was rated at 52 mpg on the hyw this did not happen it was getting 44 on average. I tried every possible thing I could think of it would occasionally get up to 48-49 but not keep this average for the week so disappointed. Luckily a hail storm hit and I was able to pick up my bolt for $26900. The sticker was $42985 so I got for what I was seeing 2017 models going for. And I do not mind the dents.
Now with this being said none of those vehicles had human input to battery longevity. So I am learning best practices form all of you. My charging will never be from dcfc the car is not equipped and as of now I am charging with the cable supplied with a 220 mod at 12 amps and occasionally at chevy dealerships 220 at 40 amps I believe. So my home recharge time can range from 9 to 12 hours depending on the battery level. Do to the distance I like the idea of a full charge if it will not degrade faster for doing this. Sorry for the long post.
 

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Thanks NewsCoulomb I believe you are the first to give an approximate % degradation. I been following you for a long time on you tube. Between your videos and post on here is what lead me to purchasing my bolt I thank you and all the crew here for your/their input.
Thanks! If you don't have DCFC, that could change things, but unless you absolutely need the full range, I wouldn't charge to 100% every day. Even if do come up short by 5% to 10% during a long day of driving, that's only an hour or so of charging on L2 AC to make up the difference.
 

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I agree, do it if you need it. Or if you like having the extra punch, and a little degradation is worth it, to you.

Based on non-Bolt specific cell physics.. how bad it is to your pack depends on when you hit 100% and how much regen braking you do near the top of your charge. If you hit 100% precisely at 7am when you leave on your commute, and If you immediately get on a long flat fast highway where there is no regen.. this is not as bad as otherwise. This is my excuse for doing it anyway.

Constant accel decel cycles right at 95% to 100% is probably the worst thing you can do to a pack.
 

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Data gleaned from 6000 EVs

Brief summary
If you have active thermal management the battery will last you a long time

To have your battery last longer.
Keep it charged between 20-80%

Avoid extreme temperatures

Don’t be afraid to Use it if you need it
Dcfc
Charge to 100%
 

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Data gleaned from 6000 EVs

Brief summary
If you have active thermal management the battery will last you a long time

To have your battery last longer.
Keep it charged between 20-80%

Avoid extreme temperatures

Don’t be afraid to Use it if you need it
Dcfc
Charge to 100%
I feel like we need to pay a lot more attention to chemistry, as well. For instance, the LiFePO4 cells tend to have a much lower lifespan compared to NCM, NCA, etc. Even within LiFePO4 chemistry, there can be variations based on anode and cathode chemistries (use of carbon versus graphite, manganese, etc.).

That's harsh, GeoTab.
29415
 

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Adding my $.02. My commute is 2500 feet downhill in the AM. I religiously use Hilltop Reserve because I drive almost exclusively in L and prefer regen to slow\stop. I would be surprised if a brake calibration concluded more than 1k miles of wear despite 56k miles on my car, I just rarely use the brakes and not having full regen is unsettling to me now.

My commute is 130 miles round trip. I have never run low enough to sweat it on normal commute days.

So, for me, not charging to 100% is a preference for driving style. If it prolongs the life of my batteries, great.

I have no hesitation charging to 100% on trips, I am confident the occasional top off is not harmful. So my vote goes in the "charge to 100% but only if you need it" group.
 

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I have read as much as I could about batteries, heat, storage, and cycling them, before buying a 2020 Bolt. I know that heat and keeping the battery charged fully in our C-Max Energi caused it to lose half of it's all electric range in 6 years.
So, we put an air conditioner in the garage, and keep it at 82 to 84 in the summer. It used to get over 100 in there, especially when it was 116 outside.
So when we bought the Bolt, it has a nice semi-cool garage to stay in. Due to COVID-19, we aren't driving much; at most 25 miles in a day. So, I charge to 60% and when I get home plug it in right away. It could be a well before driving again!
But, this helps the battery in the sweet spot for SOC, and minimizes the charge cycles by not going too high or too low.
The worst thing for the battery is to sit at a high state of charge in temperatures above 86 degrees.
The most this battery had been charged was 80% when it sat at the dealer overnight waiting to get prepped. It had arrived off the truck the day before.
So, I hope to never charge it to 100%, but, if I need the range and will be using the energy immediately, I might one day.
Like others said, time will tell.

Oh, I do charge my cell phone when it drops to 40%, and unplug it at 90ish%. Sometimes 85%, sometimes 92%. And I never leave it in a hot car!

And yes, I did discuss best methods for preserving the engines, brakes, transmissions, clutches, etc. in all my previous cars!
 

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I feel like we need to pay a lot more attention to chemistry, as well. For instance, the LiFePO4 cells tend to have a much lower lifespan compared to NCM, NCA, etc.
I am curious where you got this impression. This is not the battery industry view,


and In the DIY community the consensus is just the reverse. This Texan's experience is typical.

"At about 20k miles and about 18 months, my view of the Leaf has shifted. After two unusually hot summers, my battery is down to less than 80% of new capacity. The range reduction means I must charge to 100% for almost all charges and the car will no longer serve for as many trips as it did when new. The car's usefulness to me is much reduced. I am much amused and offended by Nissan's response, or lack thereof, to the problem.

My Hyundai conversion, with a LiFePo battery, has gone twice the miles and twice the time with less than half the battery capacity loss as the LiMn battery in the Leaf. Nissan clearly made a major blunder when selecting battery chemistry."


The only rap on LiFePO4 has been its low energy density.
 

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I am curious where you got this impression. This is not the battery industry view,


and In the DIY community the consensus is just the reverse. This Texan's experience is typical.

"At about 20k miles and about 18 months, my view of the Leaf has shifted. After two unusually hot summers, my battery is down to less than 80% of new capacity. The range reduction means I must charge to 100% for almost all charges and the car will no longer serve for as many trips as it did when new. The car's usefulness to me is much reduced. I am much amused and offended by Nissan's response, or lack thereof, to the problem.

My Hyundai conversion, with a LiFePo battery, has gone twice the miles and twice the time with less than half the battery capacity loss as the LiMn battery in the Leaf. Nissan clearly made a major blunder when selecting battery chemistry."


The only rap on LiFePO4 has been its low energy density.
Yes, I've heard that as well. The consensus in the DIY community is that LiFePO4 has the longest cycle life; however, they seem to discount NCM too easily. One thing is, they quote the 5000-cycle life for LiFePO4, which is much better compared to the 2,500 to maybe 4,000 cycle-life for NCM, depending on chemistry. But NCM chemistries vary quite a lot, and a lot of those DIYers don't have access to automotive grade NCM batteries. As we saw from that GeoTab survey, the Bolt EV's NCM battery cells have the lowest rate of degradation in the auto industry.

Also, that 5,000-cycle life for LiFePO4 also is achieved at very low C rates, and anything over a 1 C discharge rate can radically reduce LiFePO4 cycle life. I regularly exceed twice that discharge rate in the Bolt EV just getting onto the freeway. DIYers seem to simply accept that LiFePO4 cells will lose close to 5% of their capacity in just the first five to ten cycles. Something that would take nearly 100 cycles with modern NCM chemistries.

Finally, I think some of those assumptions are based off of DIYer treatment of NCM cells. I watched a recent video where a guy used Bolt EV cells for a solar backup, and he was surprised when he did a capacity test that put them about 10% to 15% higher than their rated capacity. However, when observing his discharge cycle, he discharged the cells down to ~3 V. The spec sheets for those NCM cells clearly state that discharging them to any voltage below 3.2 V will permanently damage the cells and reduce capacity. It's no wonder these DIYer's are seeing lower life on NCM than they do on LiFePO4, which might handle deeper discharges better. Basically, the cycle life tests proving that LiFePO4 have a better life than NCM might simply be geared to LiFePO4's strengths rather actually testing for real-world cycle life.

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But yes, I do agree that the LEAF's batteries in particular are problematic, and they have three issues that each compound their lifespan. The first (and most important) is a complete absence of active thermal management. No air flow. No liquid cooling. The second is configuration. While some of the LEAF's cells are stacked vertically (ideal, such as the configuration in the BMW i3 and Chevy Bolt EV and Volt), a majority of the LEAF's cells are stacked horizontally like a sandwich. In combination with no active thermal management, that's a recipe for increased battery degradation. And third (and this is where our points actually agree), the battery chemistry does play a crucial role. My understanding is that the earliest LEAF batteries did not use Mn as a stabilizing agent (the Chevy Volt did), which resulted in faster degradation; however, Nissan later improved the chemistry, but the batteries still faded more quickly than the industry average due to those factors I listed above. Finally, with the refresh (or possibly with the 30 kWh 2017 LEAF), Nissan made the transition to NCM. Now, those batteries faded even more quickly, but it turned out that was actually a software issue that Nissan was able to correct with a BMS update. I haven't really followed since, so I don't know the 2017 Nissan LEAFs with NCM batteries have fared in terms of battery degradation compared to their predecessors.
 

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No, you should not charge to 100% unless you need to. GM knows this and that is why in 2019 they came out with sliding charge software and not just hilltop reserve. All GM needs to do is get you through 8 years with no more than 40% degradation. Where were you guys six months ago when members (Vertiformed for one) wrote trolling sarcastic disrespectful opinions bashing anyone who thought that simple to follow best practices where a waste of time and an affront to all humanity? Also, if you are on a three years lease I do not care abut your opinion about this as you could fast charge twice a day in Dallas in the summer and still make it to turn in day. Sorry if this sounds rude, but there you have it.
 

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There have been many Chinese LiFePO4 OEM EVs. The most successful outside China have been buses. The only serious western OEM EV, that I know of, with LiFePO4, was the first generation Chevy Spark. Unfortunately, they are not on the GEOTAB list.

I find it fascinating that the most successful EV maker on the planet is now going to sell EVs with some variety of lithium iron phosphate cells.

The vast majority of DIY vehicle batteries have been in electric bikes, and scooters. EM3ev makes the best packs in the DIY industry. Other than being passively cooled for obvious reasons, they are built to OEM EV standards.


The majority of electric bikes, and scooters....both OEM, and DIY...are now running NCA cells.
 

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There have been many Chinese LiFePO4 OEM EVs. The most successful outside China have been buses. The only serious western OEM EV, that I know of, with LiFePO4, was the first generation Chevy Spark. Unfortunately, they are not on the GEOTAB list.

I find it fascinating that the most successful EV maker on the planet is now going to sell EVs with some variety of lithium iron phosphate cells.

The vast majority of DIY vehicle batteries have been in electric bikes, and scooters. EM3ev makes the best packs in the DIY industry. Other than being passively cooled for obvious reasons, they are built to OEM EV standards.


The majority of electric bikes, and scooters....both OEM, and DIY...are now running NCA cells.
I think it makes a lot of sense for Tesla to use LiFePO4 cells, and I think people give Tesla too much credit for "being out front" when their real strength is using what is most readily available. This was also true of their NCA 18650 cells. Those cells were already being mass produced, so it was the easiest way to get a large supply of batteries with little concern about availability. LiFePO4 presents the same opportunity.

Also, yes, a majority of DIYers use LiFePO4 cells, but again, that mostly comes down to cost, availability, and packaging. If NCM batteries were equally low-cost, available, and prepackaged (i.e., prismatic cells), they would be far more popular with the DIY crowd.

As for the electric bikes, scooters, etc., again, the NCA cylindrical cells are popular because of those same factors (cost, availability, and packaging). Those cells are made for everything from laptops to vapes, and you can literally buy them off the shelf at most electronics stores. Further, because cylindrical cells are already self-contained, it makes packaging them in different formats much easier.

Most of the NCM cells are, at this point, formatted for automotive use. That makes them less desirable for small bikes and scooters, and it makes them less desirable for home-brew packs (such as battery backup systems) because the packaging also needs to be bought or built.

Basically, just because something is the most heavily used doesn't mean that it's the best option. It might simply be the cheapest, most widely available option.
 

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I think it makes a lot of sense for Tesla to use LiFePO4 cells, and I think people give Tesla too much credit for "being out front" when their real strength is using what is most readily available.

Basically, just because something is the most heavily used doesn't mean that it's the best option. It might simply be the cheapest, most widely available option.
I love your EV advocacy efforts, but I find your anybody-but-Tesla bias tiring. Yes, Tesla has a problem which no other EV maker has. Namely, they need more cells than all of the others combined, because they are the only serious EV maker to date.
 

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I love your EV advocacy efforts, but I find your anybody-but-Tesla bias tiring. Yes, Tesla has a problem which no other EV maker has. Namely, they need more cells than all of the others combined, because they are the only serious EV maker to date.
I'm simply being candid and honest. It's not a value judgment either way, but if someone wants to replicate what Tesla has done, they can't go in thinking Tesla is some magical unicorn so much more capable than everyone else. The truth is, they simply built EVs using what was widely available at the time. That's not a bad thing. If anything, it's more of an impugnment of the rest of the auto industry's claims that EVs weren't ready.

Basically, I'm paying Tesla a compliment, though it's probably not a complement they (or their fans) want to hear.
 

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If anything, it's more of an impugnment of the rest of the auto industry's claims that EVs weren't ready.
I don't think there was any way for profitable legacy makers to make EVs a success...any more than Kodak would have promoted their digital camera. I think any real competition for Tesla will come from China. Maybe it is already happening.

 

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Agreed, industry tend not to want to cannibalize their own business to reinvent themselves. Reason we did not already have EVs several decades ago with NiMH batteries.
 

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Agreed, industry tend not to want to cannibalize their own business to reinvent themselves. Reason we did not already have EVs several decades ago with NiMH batteries.
Except when we did: GM EV-1 NiMH in 1999. I drove three of them, two '97 PbAs and a '99 NiMH. They made a small amount (very low 1000s), and leased every one they made.

 
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