Came here from Jason from Engineered Explained. Great explanation Sir!

@SreehariVariar

4 ай бұрын

Me too. Watching a second time now.

@adon8672

4 ай бұрын

Same.

@deepakvpcec

4 ай бұрын

Same here. Thanks for the great explanations.

@kdkd693

4 ай бұрын

Same

@billycan8852

4 ай бұрын

Same

Great video, I also found this via Jason at Engineering Explained. He was right well worth a watch. Great info.

@ElectricVehicleSociety

3 ай бұрын

Glad it was helpful!

@ElectricVehicleSociety

28 күн бұрын

FYI, Jeff Dahn will be returning for another presentation on August 6, 2024. He will do another Q&A session as well.

I drive long distances as part of my job and I now have 100,000km on my 2022 Tesla model 3 LFP. I charge almost every day to 100% and regularly drive the battery down to near 0% state of charge. When new I had 428km on the GOM at 100%, today it shows 417km at 100%. I haven’t noticed any difference in performance and the only maintenance items have been tires , wiper blades, cabin filter and lots of washer fluid. I plan to drive this car til the wheels fall off.

@ElectricVehicleSociety

2 ай бұрын

Your LFP Battery should last a very long time and they are getting better every day!

@nissan_skyline

18 күн бұрын

Thank you for sharing. I feel so much better about my vehicle purchase when I see personal stories like this.

Many thanks to Dr. Dahn for his patience talking to a [relatively] naive audience! 53:00 Targeting a specific number for optimum SOC is silly - to drive your car any practical distance, you must inevitably lower the SOC, while your range improves at a higher SOC. Jeff has it right - IF you can operate routinely between say 30% & 75%, good for you, but if you are heading out on a long trip then don't be afraid to charge to 100% the previous night, & don't sweat fast charging on a long trip. Just try to avoid 100 % SOC routinely. My personal choice would be a car with a LFP battery, for which the optimum range of SOC is legitimately much closer to 10% ~ 100%.

I have a year-old Dell laptop computer that spends most of its time on the kitchen table, plugged into an AC outlet, and only occasionally goes on a business trip with me when I would need/want maximum battery run time. On the basis of Dr. Dahn's advice, I have now set the laptop's charge limits to operate between 30% & 70%. The night before a trip, I'll charge it to 95%. With luck I should get many years of battery life!

Dr. Dahn has makes the best presentation I've seen to explain why batteries lose capacity, why new chemistries show so much promise, and glimpses into new chemistries coming. 1.25 million kms, to 6 million kms, is certainly a product longevity target well beyond anything ever offered by the automotive industry in the past.

Thank you for this very interesting video. 42:43 I would love to listen to Jeff Dahn speak about LFP batteries because those batteries will be in most Teslas in the near future (it's already the case in Europe)

It's great to see this talk from a Li-ion battery expert rather than just typical EV reviewers repeating the same battery health tips.

@nissan_skyline

18 күн бұрын

Omg, I was thinking the same exact thing. Dr. Danh also had a 5 year research partnership with Tesla for battery development. So I would take his advice over your everyday EV car owning KZreadr any day.

Wow, what a great interview and thanks Dr Dahn for being so generous with your time. Much appreciated. I've been part of the Victoria EV Club for about a decade and we used to have lots of educational sessions and this topic of charging always comes up. Now we know the answers!!! thanks. BTW, I have a 2014 Leaf with the 24kWh battery and it still have 11 bars but I think it's due to lose another soon as Leaf Spy tells me its GIDS are the mid 80's. I only charge on my home 120v and 220v Sun Country 30 AMP charger. I've never used a L3 but the previous owner in San Francisco area did about 22 L3 charges according to Leaf Spy. The older Leafs only have a timer and you can't specify to only charge to 75% or 80%, so it usually gets charged from 35% to 100% unless catch it earlier. Many have said that its best to do many short duration charges so I guess I'll have to start doing that more often. Luckily we never get too hot here in Victoria, rarely over 25°C and even at that I don't charge during the day when it's that warm. Car has about 86,000 km on it and it's been flawless and a pleasure to drive ...recognizing that the older Leafs are city cars and not practical for longer trip. Thanks again for the great show and I'll try catch more of your content. Don Scott

Many thanks from a first time EV owner (Tesla Model Y) in the UK.

Thanks to Dr. Dahn for sharing his incredible knowledge (and clearly a passion!)- amazing information for techies like me who want to understand more - and thanks to the organizers of the event.

@ElectricVehicleSociety

10 ай бұрын

Great to hear!

As a chemist and scientist I did get most of this specialised talk, Wonderfull explanations. I have 2 EV, a Honda Clarity Phev 2021 and a 2022 leaf 40 kWh but no vehicule battery chemistry so I cannot maximise battery life span. I do live in Canada, Montréal, so from your talk I think I understand the following: 1 in winter charge up to 100 % and drive to 75% before charging. In spring and fall do the same but in summer store the vehicles at 30% if not usining for more than a month and charrge and discharege between between 75 and what % od discharge ? I guess my main comment is that there should be legislation to inform consumers as to the optimal operating parameters of EV batteries when sold. Again great wideo thanks.

Like thelinuxdude, I too got to this video thanks to Jason. My 2015 model S battery is charged to 85% on cooler days, less than 25 deg C and on hot days above 28 deg C at 50%. Great video.

Nobody seems to talk about how bad PHEVs are (relative to BEVs), in this respect. I had a 2017 Hyundai Sonata PHEV in Phoenix, and i would cycle it 15 to 100% during my daily commute. My battery was replaced under warranty at 44,000 miles. It took 6 months to get the new battery.

@SDGreg

3 ай бұрын

It really depends on the reserve that the manufacturer uses. The 1st Generation Volt only allowed 65% of the battery capacity to be used. So even though the owner thought they where charging to 100% and going down to 0% they where only using 65% of the actual battery capacity. Obviously this is going to be very dependent on how much reserve the manufacturer uses on the battery. GM was very conservative with the Volt.

@Krunch2020

3 ай бұрын

Good comment @SDGreg. When the actual charging parameters are hidden from us we are left with tribal lore like “Tesla has better battery protection than Hyundai.”

any possibility to have an additional video specifically on LFP chemistry? the recommendations on those are not that clear

Very cool. Just got a Model Y and Tesla recommended 80% under normal circumstances. I just lowered it to 75%.

Great video. Found this Channel when I was searching for Aptera, Solar Electric Vehicle that can add up 64 kms per day from Solar Charging on a sunny day. #SEV

Thanks very much Jeff! You are a Canadian legend.

Which cars use batteries with monocrystals?

It would be good to get the science around not letting your charge drop too low. We are told its bad but interested in the science

Thanks so much! I knew a great deal of this already as I’ve always wanted to know how to best look after my car’s battery, just as I do with the engine in my other (ICE) vehicle. HOWEVER I still learnt from this, so a huge thanks. (My 4.3 year old Model 3 has absolutely minimal degradation as I’ve always tried to look after it - which is actually very easy to do as long as you make just a little effort. It’s actually never been above 95% in it’s life as that leaves me a bit of regen available and is kinder to the battery for absolutely minimal reduced range.) Particularly in Summer, I try to keep it at 70% max except immediately before a big trip. The trip computer Is so accurate that forward planning is actually dead easy.

One thing I'd really like to get clarity on from Dr Dahn on the Ecker and co. paper is to appraise how true the 40-60% goldilocks zone and the 25% DOD really is. The data is really quite interesting, but I'm not quite convinced because of what I would call critical interpretations. First, for the a-axis and c-axis plotted against SOC, are these anisotropic volume changes state-independent? In other words, will a reference cell follow these recorded displacements perfectly and without hysteresis, independent of whether they were undergoing charging or discharging at the time of measurement? Depending on the methods used to record these displacements, there could exist a second set of anisotropic displacement curves that elude the interpretations gathered from this plot. When Dr Dahn described 25% depth of discharge as having superior degradation compared to 50,75, and 100% DOD, the starting and ending voltage is not noted. It should go without saying that "25% depth of discharge" does not mean the same thing when it starts at 100% compared with a discharge from 60% SOC, and that goes with all permutations of 25,50, and 75% that fit along the 0-100 scale. The only reasonable assumption for "Depth of Discharge" is that a discharge always begins from 100%, unless the starting and ending SOCs are expressly stated with DOD. This has always been the case for other battery chemistries like lead-acid, nimh, nicad, etc. The other problem I have is comparing the 25% DOD (from 40-60%?) with extremes such as the single cycle-fresh cells and the 100% DOD cells. Intuitively it follows that you can compare a sort of progression in the morphology, and there is some value in this, but the meaning is lost completely when we start to discuss microcracking. When the displacements in the a-axis and c-axis are expanding and contracting in not just an anisotropic fashion, but progressing nonlinearly, how can you be confident you know how these microcracks evolve across the range? The most you can conclude is you've found a region where the slopes of displacement are at a minimum in the 40-60% range. However, where is the microscopy and cycle depth data showing how stresses and degradation evolve everywhere along the SOC vs displacement curve? Where is 0-25%, 5-30%, 10-35%, 15-40%, 20-45% etc, keeping DOD constant while shifting along at discrete increments? Why weren't all the depth of discharges compared from the same starting voltages if electrode internal stress is a function of SOC? Why not evaluate cycle depth schemes that remain on one side of an inflection point of the displacement vs SOC curve as opposed to just a range with the smallest slope of displacement vs SOC? If the rest state of the polycrystalline particles with the least amount of internal stresses was 0% rather than 50%, a cycle depth closer to 0% would produce less degradation than one at 50%, even if the change in displacement was smaller, yet there is no data to explore this conclusion because the smallest SoD / EoD was 40-60%. What about rate-dependent stresses? Is the 0-40% SOC range fine if the C-rate is low enough? Is this stress and displacement temperature-independent? Clearly, there is much more research and consideration to be done for this topic, but I would really like to see depth of discharge's use in literature changed to be more specific to avoid misinterpretation, because I really don't see it as a useful measure on its own. Better yet, if it was challenged in favor of looking at wear in terms of end-of-charge voltage rather than depth of discharge, leaning on Chois, S.S., & Lim, H.S. (2002) and their work, even more robust conclusions could be made.

Please do a video like this for LFP batteries! Im particularly interested: what happens if you never charging an LFP pack to 100% to balance the cells; given the lower voltage at 100% does it experience the same risk of cracking at high voltage?; does the same principle of regular charging apply?. Thank you!

@andre_renard

4 ай бұрын

The main reason for charing LFP to 100% is because it has a very flat voltage curve with discharge - so it's very hard to tell how charged the cell is. With NMC voltage = charge, but no so with LFP. Charging to say 80% could result in a situation where some cells are 80% and some are say 85% or 70%. The BMS will stop the pack once any one cell hits the low voltage cut-off to avoid damage, so you might think you have 80% when really you only have 70%. My understanding is that LFP doesn't suffer the same damage when charing to 100%, and generally has a very long life span. Most LFP cells claim 3000+ cycles with 100% charge and discharge to 20%. With LFP the main issues seem to the with temperature (cannot charge when cold), and with going to a very low state of charge. Almost all LFP datasheets seem to have reduced cycle life going below 20% SOC. I think Tesla's advice to charge to 100% as often as possible makes sense for LFP - and my guess is one shouldn't go below 20% too often (although most people will naturally want to charge then anyway). Having said that, I'm hoping Dr. Dahn will do a public talk on this at some point. I'd love to know more about what's happening here at the chemical level. I know a lot of LFP cells have to be kept under compression for best life span, and that's something I've never understood.

@figueiredoeduardo7252

3 ай бұрын

Hello Andre, great explanation. Sometimes I arrive at work with 90%. Do you think it will be ok to plug in everyday? By the way, I have a LFP Tesla model 3

@nissan_skyline

18 күн бұрын

LFP battery packs are known for their stability and long cycle life compared to other lithium-ion chemistries like Nickel Cobalt Aluminum (NCA). Here are the implications of never charging an LFP pack to 100%: Cell Balancing: In LFP packs, like all lithium-ion batteries, cell balancing is crucial. Cell balancing typically occurs at the top of the charge cycle when the pack is charged to 100%. If you never charge the pack to 100%, the cells may become unbalanced over time. This imbalance can lead to reduced performance and capacity, as well as potentially reducing the lifespan of the battery. Lower Risk of High Voltage Stress: One of the advantages of LFP batteries is their higher tolerance to overcharging compared to other chemistries. The maximum voltage for LFP cells is lower (typically around 3.65V per cell) compared to NCA cells (which can be around 4.2V per cell). This means that even at full charge, LFP cells experience lower voltage stress, reducing the risk of cracking and other voltage-related degradation. Regular Charging Practices: 1. Charging to 100%: While LFP cells are more stable and have a longer cycle life, regular charging to 100% is recommended for cell balancing purposes. However, frequent charging to 100% is not necessary for everyday use and can be done periodically, like once a month (I believe Tesla recommends once a week for their LFP powered cars, according to their drivers manual), to ensure cells remain balanced. 2. Avoiding Deep Discharge: Like other lithium-ion batteries, it is also important to avoid deep discharge of LFP cells. Keeping the state of charge (SOC) between 20% and 80% for daily use can help prolong the battery’s lifespan. 3. Temperature Considerations: LFP batteries are more tolerant of a wider range of temperatures, but it is still advisable to avoid extreme temperatures during charging and discharging. Comparison to NCA Batteries: 1. Voltage Tolerance: NCA batteries require more careful management of charging to avoid high voltage stress, as they operate at higher voltages. This makes them more susceptible to degradation from high voltage cracking compared to LFP cells. 2. Cycle Life: LFP batteries generally have a longer cycle life compared to NCA batteries, which is why they are often used in applications where longevity and safety are more critical. I hope you find this information helpful.

@figueiredoeduardo7252

18 күн бұрын

@@nissan_skyline thank you very much! I’ll charge is daily to 85-90% and once a week 100%. That should preserve the battery ☺️😉👌

I knew about storing Li-ion batteries below 50% in a cool location, but the depth of discharge effects was surprising. I would have thought the speed of charging would be a factor in battery lifetime. But I assume since the battery and chargers communicate to each other, you're not worried about overheating during charging.

This video was perfect, it is very nice to see an expert scientist talking in such a understandable language - thumbs up Dr. Dahn

@ElectricVehicleSociety

3 ай бұрын

I completely agree. He takes pure science and makes it understandable and useful.

@user-xp6zy6oe9j

3 ай бұрын

@@ElectricVehicleSociety As being scientist myself, I really know how hard that is. Furthermore, this video made me happy as I had this kind of regime in my driving (have Hyundai IONIQ, 2022) and now see me driving this car for years 😊

@ElectricVehicleSociety

3 ай бұрын

... and the IONIQ is a really nice car. Enjoy!

Hello Dr. Dahn. I've been referred by Engineering Explained channel. Thank you for your great explanation.

Wait a second... did I get this right?? If I cycle my battery 01%-21% the battery is happy?? We've always read everywhere the following: "Never let your battery go below 20% you will spoil it!"

@rubyredlexusES350

4 ай бұрын

I suspect that this low charge range was simply not addressed because nobody would ever actually operate an EV that way. We can ask Dr. Dahn directly the next time he is on the webinar.

@robertlucas2305

4 ай бұрын

@@rubyredlexusES350 Yes please! 🙏

Fantastic stuff! Please leave these videos up. I try to share them with people and they have been made private. This is EV battery education 101 stuff! Thank you so much! I will be following this advise for my own battery care.

@ElectricVehicleSociety

10 ай бұрын

Thank you! We will keep the videos up for sure.

This is fantastic! Thank you so much for this information. Own a Crosstrek PHEV and need all of my range. My typical habit was to drive it down to very low battery and then charge it up to around 95%. I see now that just charging whenever I have the opportunity and only losing / gaining back small percentages is a far better way to approach my daily commutes. I have to charge at public chargers most of the time, but I certainly have the opportunity to charge for small periods of time during errands. I always thought that charging for smaller amounts, multiple times each day was a bad habit for battery health. Thankfully this is not the case.

@LoneStarr1979

4 ай бұрын

Your Information / charging advice is true for NiMh and especially for NiCd batteries which where used in the earlier laptops and cellphones (and are still as aa/aaa cells) Many people (including me) were not aware that the newer devices with their Li-Ion batteries needed another charging habit... which lead to many laptops and cellphones dying fast ... which lead to the general "knowledge" that Batteries do not last long. The typically high temperatures in laptops do not benefit that, either. All in all this is a very good example that knowledge about a component can not always be easily transferred from one use case to another.

Thanks, very clear information. I will share it. I'd love to have the same info for LTO lithium titanate technology.

Great talk! Would it be possible to get a followup on LFP cells. I'd love hear more about LFP battery life considerations, as those are becoming more popular among entry level EVs.

@rubyredlexusES350

4 ай бұрын

Dr. Dahn is coming back this year for an extended Q&A. We can ask him that then.

@JohnSmith-rt5yq

Ай бұрын

That would be great, they are popular now and im sure many of us would want to know more about them for proper care. Thank you!! ​@rubyredlexusES350

Great video! Can you make a video on LFP batteries! Is there anything we can make to make them last longer?

@ElectricVehicleSociety

2 ай бұрын

Going to ask Dr Dahn back in July or August. You may be able to ask him yourself directly.

Skip housekeeping to 3:13 presentation

Can we get a quick talk like this but about lfp batteries as they advise them to be charged to 100% once a week.

@ElectricVehicleSociety

4 ай бұрын

Dr. Dahn will be back for another episode in 2024. You will be able to ask him your question directly. Date is TBD.

Amazing information !! Just one question, on 20:00 when you talk about cycling, that includes the buffer ? Or simpy is the whole capacity of the cell ? Thanks so much !!!

Very informative, thank you sir!

Such a great technical video loved it. Came here from engineering explained channel.

@ElectricVehicleSociety

4 ай бұрын

Glad you found us. Welcome!

Thanks Dr Dahn for the detailed and insightful sharing. My car has a NMC811 battery. Regarding the degradation by charging to 75% vs 100%, does the charging speed matter? I heard from others that medium speed (eg. 11kW) brings less degradation than high speed (eg. 50kW). Thanks!

Thanks. Great to know about the single crystal. And we are still really early in battery development. Ten years from now we will all be amazed at the progress in batteries

@ElectricVehicleSociety

10 ай бұрын

Agreed. We will see some amazing advancements in the very near future.

Came here from reddit :)

Great analysis, but I wonder, why is a state of charge of everyday use (for a 400km vehicle) between 10% and 50% would not be even better than 40% to 60% all time charging? If one does not need more that 40% of usable capacity, it should be almost best option, or? Please do not mention letting the battery to fall to 0%, I understand this might be the reason not to mention these low SOC-s

Excellent! Thank you!

Great video, question, you've mentioned long range several times, how would you adjust this on a standard range model? Would you still suggest charging to 75% or would you go lower? Thanks!

@ElectricVehicleSociety

3 ай бұрын

We will have Dr. Dahn back later this year. The plan is to make it mostly a Q&A episode, and I think we will begin by asking him questions that have come in from KZread comments and email. Will try and get your question on the list. Thanks for your comment/question.

Thank you for this informative video, I shared it to all my Tesla brothers.

If a summer trip is planned would you recommend plugging your EV in and setting the upper limit of charge to 30%.

Great information. Dr. Dahn touched on level 3 charging (supercharging to the Tesla community) briefly. Please confirm.... There is no difference, as it relates to battery degradation, whether you charge using a supercharger or level 1/2, since then BMS will protect the battery. If so; This is another huge area of misinformation.

Great presentation but I didn't hear about the effect of low discharge. So, how does it effect battery life if you go down to less than 10 or 5% (even if you only charge to +75%)?

My car has a 3.5kWh buffer not in the available to be used number. Is it likely to be at the bottom end, spread evenly or at the top end? It makes a difference as to where the say 75% marker 'in vehicle' is.

Great info, thank you!

@rp9674

3 ай бұрын

Yup

He mentioned it is better to have smaller charge swings more often than larger ones less frequently. In that case which is a better charge swing: 35-55% or 55-75%?

@ElectricVehicleSociety

6 ай бұрын

I think he would say the difference would be minor but that a lower averate state of charge is always better.

Is there any downside to plugging in too often? My daily usage is only 5%. In other words, would it be better to plug in every 3-4 days so I don't accumulate too many charge cycles?

@rubyredlexusES350

4 ай бұрын

No downside to more frequent, shallow charging sessions. It's actually better for the battery.

Dear D-r Dahn, what about NCMA batteries how do they handle 100 % charge?

I need to know more about LFP batteries.... should tbose also not be charged to 100%? I wish he had gone into it, its what my car uses...

@ElectricVehicleSociety

28 күн бұрын

FYI, Jeff Dahn will be returning for another presentation on August 6, 2024. He will do another Q&A session as well.

Does leaving the car plugged in have any impact on the extreme temperature storage at low state of charge recommendation? As someone in the Phoenix AZ area you mention, my high nickel battery Tesla when plugged in only allows a minimum of 50% soc, but if it's plugged in shouldn't the thermal management system keep the battery at an optimal temperature even though my garage can be well in excess of 50 degrees C? Thank you for the great talk

@Jeddin

8 ай бұрын

Tesla recommends keeping the battery plugged in as 50% soc is not much worse then 30% soc for storage but has the added advantage when plugged in of allowing the Tesla when plugged in to engage it’s temperature control systems to maintain the battery at optimum temperature otherwise you will be baking your battery in that 115 degree phoenix sun

Do Hyundai Ioniq 6 have single crystal material in the battery ?

I would think EV manufacturers who used "single crystal" batteries would advertise this fact.

@ 34:00 what if we charge to 80%, how much degradation over the life of the battery?

very helpful

@rp9674

3 ай бұрын

It is

Amazing video

@ElectricVehicleSociety

28 күн бұрын

FYI, Jeff Dahn will be returning for another presentation on August 6, 2024. He will do another Q&A session as well.

My apologies if this has already been addressed. I've set my daily maximum SOC to 50%, my daily use is 20%- 25% DOD, and I charge at home every night on a level II charger. Is my max SOC at 50% ideal, or would you recommend a higher daily maximum SOC%? For longer trips, I'll charge to a larger SOC prior to departure. Thanks for your time. MR

@ElectricVehicleSociety

Ай бұрын

Based on Dr. Dahn's advice, in a perfect world, you probably want your average SOC to be 50%. You could probably bump up your daily charge to 60 - 65%. Unless you reside in a hot climate, this minor change to your charging routine would have very little impact on battery life however. We hope Dr. Dahn will be back for another episode soon and I'm sure he will be happy to confirm this.

@datubaguy

Ай бұрын

@@ElectricVehicleSociety Thanks

@ElectricVehicleSociety

28 күн бұрын

FYI, Jeff Dahn will be returning for another presentation on August 6. He will do another Q&A session as well.

On 20:00 the % of discharge, also includes the buffer protection ? Or is it the whole cell capacity ? thanks so much !!

@rubyredlexusES350

4 ай бұрын

I believe Dr. Dahn was asked this during the Q&A.... he said this was at the whole cell level.

@gery4870

4 ай бұрын

@@rubyredlexusES350At 45:15 he said is counting for the 100% of the vehicle (that means including buffer)

Can you please provide some long term info, for example 10 to 20 year timeframe? Since the timeframe tested are so short, it almost appears these batteries are not expected to last this many years?

@theophiluslamptey47

6 ай бұрын

The shallower the discharge the longer the battery will last

Salutations

Jason sent me

Is charging once a week from 35% to 80% fine?

@rubyredlexusES350

4 ай бұрын

Yes, this is a very healthy range for your state of charge but if you can charge more often, it would be even better.

Is there any evidence you need to charge periodically to 100%, for ultimate battery health? If so, at how many cycles?

Does charging to 80% implies significantly more degradation than 75% charging? All automakers are suggesting 80% as a threshold

@Y2Kvids

4 ай бұрын

That's about 75% because they don't allow 100% charging at the top even it says 100%

@rubyredlexusES350

4 ай бұрын

While 75% is better than 80%, the difference to battery health is likely marginal. This is certainly true unless charging in extremely hot temperatures.

@GreenDriveIndia

4 ай бұрын

Lower the better

I’m back to school 😅

There is one thing you don't address. And that is balancing the cells in a battery. As long as it is not possible to get the internal resistance in two cells 100% equal, the BMS must help. If you do not blanch, one or more cells will stand up like a nail on a flat floor. And that will over time reduce the capacity of the battery. I have learned that the balancing must be done when the battery is fully charged. But it is somewhat inconsistent with the fact that one should not charge the battery up to 100%. But what is right and if I am right, how often is it appropriate to balance and how long must be set aside for balancing the battery?

@ElectricVehicleSociety

2 ай бұрын

Great question. Dr. Dahn will likely be back this year for another webinar in July or August 2024. I'm compiling questions like yours to send to him in advance. Thanks.

@magnestoreb5959

Ай бұрын

@@ElectricVehicleSociety There is one more question that is of great interest. It is about cycling these batteries in lower voltage fields. Basic chemistry dictates that in a chemical "bathtub", such as a battery cell, it is necessary to "empty" the battery completely, i.e. down towards the lower voltage limit to keep the chemical processes available. Everything that is not used degenerates over time! It may also be of interest to help the BMS to find a zero point for its calculations with regard to how much energy it is in the battery. A comment on these questions would have been helpful.

@ElectricVehicleSociety

28 күн бұрын

Confirmed: Jeff Dahn will be returning for another presentation on August 6, 2024. He will do another Q&A session as well.

So hybrid batteries should last a lot longe.r

Discussing these recommendations in terms of percentages isn't actually that helpful because EV manufacturers using NMC are at liberty to set their own cutoff and end of charge voltages in their cars' BMS, and will just constrain 0 - 100% within that arbitrary range which can dramatically depart from your 4.2V=100% relative battery state of charge. So an end-user recommendation to charge no higher than 75% might not actually turn out to be 4.08V, it could be be closer to 3.88V, reducing stored capacity dramatically. In actuality, those end-users could have safely charged to 100% because the 120mV was already taken off by the MFR. Of course, the amount of information and feedback provided to EV dashboards and infotainment screens without an OBD II tool is scarce to nonexistent, and drivers often have nothing to go by besides the illusive percentage SOC in a small corner of their screen, so its very relative advice across different vehicle makes. I would hope in the future that better data like min/max/average cell voltages would be provided to EV drivers as literacy in this subject grows.

@davidroberts5199

4 ай бұрын

I've yet to see an example of a battery in an EV that limited the voltage by more than a couple of percent. My current PHEV tops out at 4.175 which is waaay higher than I'd like. All the measurements I've seen from other EVs are similar. Teslas at 4.15 for example. I agree we would all benefit from seeing the actuals on the car's display rather than having to use third party plug in adapters and apps. Dr Dahn worked with Tesla so likely is familiar with their practices at least. Manufacturers are in a difficult position because they obviously want the battery to last well (at least past the warranty period) but they also need to show a competitive driving range to get sales.

@Infinion

4 ай бұрын

@@davidroberts5199 They limit the end of charge voltage in my Spark EV, top voltage is 4.08V-4.12V depending on temperature. I've seen 4.12V with a hot 22ºC battery, and 4.08V with a 13º battery. If I go down hill with a 99% battery, the battery voltage will climb to 4.15V with about 7-10kW of regen. Bolt and Volt might do the same thing.

@davidroberts5199

4 ай бұрын

4.12 and 4.15 are much higher than I’d like my battery to go on a regular basis. And that’s on a minority of EVs. The market leader, Tesla allows much higher voltage and SOC.

Based on my experience it seems that some Li battery’s can repair themselves. I’ll give you two examples. I was forever charging to full my MacBook Air and it lost the ability to work more than 10 minutes without plugging it back in. I began charging it up to 50 or 60 per cent and in about a month it began lasting me several hours without being plugged in. Example 2 is my 2018 Nissan Leaf. I was vigorously charging it to 100% and my range dropped from 160 miles per charge to 80 miles per charge. I began only charging it to 80% and in several months I was getting 150 miles to the charge. It seems that some types of lithium batteries can heal themselves, similar to the human body.

@Y2Kvids

4 ай бұрын

It could be a calibration issue .

@Infinion

4 ай бұрын

I cant say for sure that NMC will repair itself, but in '22 I read an article from Stanford uni based on the paper "Dynamic spatial progression of isolated lithium during battery operations" (Fang Liu et al., Nature, 22 December 2021 ) describing the procedure to recover lost or inactive lithium and bring back capacity. Essentially the procedure is to charge the cells, then slam high discharges through the battery. This act electromagnetically attracts tiny lithium precipitates towards the anode. After enough nudges, the lithium will creep close enough to the anode to make physical contact with it, and electrons will start exchanging with those lithium islands, allowing that lost lithium to chemically react and do work for the battery again. Fang Liu describes some possible contributing factors are the applied current density from your intense discharge, the orientation of the percipitated lithium dendrites, and the dendrite length that becomes polarized in that electric field. keep in mind, they say it works for percipitated lithium, but not for SEI and CEI based degredation.

@coffeeisgood102

4 ай бұрын

@@Infinion …Thanks. That is interesting and seems to make sense.

Anybody want to give a TL:DR version?

@kilgary

4 ай бұрын

37:28 The recommendation is to normally charge to 75% and charge often. 41:22 Keeping the battery between 70%-45% most of the time is ideal and leaving it at 30% when you go on vacation is better than leaving it fully charged.

@D0praise

4 ай бұрын

And if you follow the recommendations you can get millions of miles out of your battery

@LTVoyager

4 ай бұрын

To use a gas car analogy. It is like having a gas tank where the upper 40% of the tank is rusted by gasoline and the lower 40% is rusted by air. If you fill your tank above 60% of capacity your tank will rust from gasoline and develop a leak. If you let the tank get below 40% full the tank will rust from air and develop a leak. So, let’s assume you have a car with a 10 gallon tank that gets 30 MPG. The car maker advertises a range of 300 miles. However, if you use that range you will develop holes in gas tank. So, your actual range is 60 miles as you can only use the 2 gallons of gas between having 6 gallons in the tank and 4 gallons in the tank to avoid damaging the tank. Is that simple enough?