7 ms·

From having worked a bit in the industry I'm a bit skeptical about this study, I've definitely seen studies and experiments that used different initial charging

by starky 2y ago

From having worked a bit in the industry I'm a bit skeptical about this study, I've definitely seen studies and experiments that used different initial charging conditions that would have shown better fade performance if this was true. Not to mention, how much does the increased SEI change the impedance of the cell (thus reducing the subsequent charge speed) and the capacity available.

m463 2y ago
Wasn't supercharging EVs a lot frowned upon at first, but later found out not to negatively affect battery life as much? https://electrek.co/2023/08/29/tesla-battery-longevity-not-affected-frequent-supercharging-study/ https://electrek.co/2023/08/29/tesla-battery-longevity-not-a...
- starky 2y ago
  How long does supercharging take? Even at 30 minutes, that is only a rate of 2C which is not that extreme for some cell chemistries as long as temperature is controlled.
  - jazzyjackson 2y ago
    Watching the comparison of a cyber truck vs a ram 2500, supercharging at 250kw took an hour and a half https://youtu.be/HIs8zudJFzg https://youtu.be/HIs8zudJFzg
- Roark66 2y ago
  This may be so in Teslas that have quite robust heat management. It definitely doesn't apply to many other brands. Anyone who knows anything about lithium batteries and sees temperatures at which fast charging is done will not believe any of the longevity claims. It is up to 55C during charging and during subsequent driving on a motorway it can take half an hour for this temperature to drop below 40C (look up BYD Seal 1000 mile challenge on YouTube for an example - all above st 9C ambient).
  - atwrk 2y ago
    BYD started as a battery producer and still is one of the largest in the world - I can't imagine them not having considered proper thermal management for battery health. Especially since they have been producing electric buses since 2010, which, as utility vehicles, see way higher usage (=charges) than consumer cars.
    - chrisandchris 2y ago
      I can imagine, and I can also imagine the buyer of those batteries stripping down "functionality" because of costs. So EV cars on the lower end could have higher peak temperature, because it's cheaper (i guess).
    - delusional 2y ago
      Is it a case of them not thinking about it, or did they think about it and figure that consumers would not pay for the increase in quality? Plenty of engineered things could be "better" if price wasn't a concern. Most of this board can probably think back to a time where they had to leave long term value on the table because of short term costs concerns. It doesn't seem impossible to me that the engineers would leave some battery longevity (something that's hard to gauge for the consumer) on the table in pursuit of faster charging speed at lower prices (headline marketing items).
  - jve 2y ago
    And because of this, electric vehicle manufacturers should take note. If only for a city only car that you mostly charge at home, don't do roadtrips with multiple fast charges in short period of time you may get away with passive cooling. And if you don't live in a hot climate. But those are too many IFs.
    - sokoloff 2y ago
      That describes our use case pretty well (for a 2-car household) and we’ve been quite happy with the 26K miles we put on our Nissan LEAF in MA over a coming up on 10 year period. Charged at home >50% of the time and pre-pandemic on the 6.6kW chargers at work. I can only recall one attempt we made at a beyond single battery trip, using an EVGo DC charger at the mid-point. I can say it worked, but subsequent trips to that same location were in the ICE car, so take of that what you will. The car is now 80+% charged at home and is a city/nearby suburb runabout (and used for more trips, albeit not more miles, than the other ICE/hybrid). It still has about 85% of its original battery capacity, which means we charge it about once a week, which works just fine for us.
Joel_Mckay 2y ago
Agreed, the study summary needs better explanation to justify the contradiction with dozens of other lab tests. We have several boxes of 21700 cells from various manufacturers (Samsung/Sony/Panasonic) undergoing aging trials for over 2 years now. All LiIon and LiPol chemistries have shown the following: 1. deep-cycle discharges below 60% full cuts usable charge cycle counts from 8000 to under 2000 uses. 2. high-current discharge or rapid-charging accelerates capacity losses by about 15% a year 3. Internal resistance goes up as dendrite defect shorts damage the cell. Additionally, the self-discharge rates increase as the cell is degraded. Very surprising if the technique works for all cell chemistries. =3
- gamblor956 2y ago
  There isn't a contradiction. This study solely focuses on the very first charge. It doesn't claim that recharging at high currents benefits battery life, only that the first charge at high current forms a larger protective barrier than a first charge at a low current. Other studies have shown that a larger protective barrier improves lifespan. (See other comments on this thread for more details on the science.)
  - Joel_Mckay 2y ago
    Some early Microchip LiIon chargers did not split the cycle into 3 to 4 stages (pre-prep, CC-prep, and CV rapid charge). i.e. they would drop into a constant-voltage rapid charge mode assuming the cell was prepped already. None of these systems showed any sort of increased capacity or longevity. Quite the contrary results, this is why the new study details are rather intriguing. =3
    - gamblor956 2y ago
      The problem was probably the pre prep stage.... that appears to count as the first charge as it is defined in this newer study. When they say "very first" they mean it very literally.
      - 2y ago
oska 2y ago
The analogy they use in the article is all sorts of dodgy too : > Removing more lithium ions up front is a bit like scooping water out of a full bucket before carrying it, Cui said. The extra headspace in the bucket decreases the amount of water splashing out along the way. In similar fashion, deactivating more lithium ions during SEI formation frees up headspace in the positive electrode and allows the electrode to cycle in a more efficient way, improving subsequent performance.
deleted 2y ago
[deleted]

by starky 2y ago

m463 2y ago

Wasn't supercharging EVs a lot frowned upon at first, but later found out not to negatively affect battery life as much? https://electrek.co/2023/08/29/tesla-battery-longevity-not-affected-frequent-supercharging-study/ https://electrek.co/2023/08/29/tesla-battery-longevity-not-a...

starky 2y ago
How long does supercharging take? Even at 30 minutes, that is only a rate of 2C which is not that extreme for some cell chemistries as long as temperature is controlled.
- jazzyjackson 2y ago
  Watching the comparison of a cyber truck vs a ram 2500, supercharging at 250kw took an hour and a half https://youtu.be/HIs8zudJFzg https://youtu.be/HIs8zudJFzg
Roark66 2y ago
This may be so in Teslas that have quite robust heat management. It definitely doesn't apply to many other brands. Anyone who knows anything about lithium batteries and sees temperatures at which fast charging is done will not believe any of the longevity claims. It is up to 55C during charging and during subsequent driving on a motorway it can take half an hour for this temperature to drop below 40C (look up BYD Seal 1000 mile challenge on YouTube for an example - all above st 9C ambient).
- atwrk 2y ago
  BYD started as a battery producer and still is one of the largest in the world - I can't imagine them not having considered proper thermal management for battery health. Especially since they have been producing electric buses since 2010, which, as utility vehicles, see way higher usage (=charges) than consumer cars.
  - chrisandchris 2y ago
    I can imagine, and I can also imagine the buyer of those batteries stripping down "functionality" because of costs. So EV cars on the lower end could have higher peak temperature, because it's cheaper (i guess).
  - delusional 2y ago
    Is it a case of them not thinking about it, or did they think about it and figure that consumers would not pay for the increase in quality? Plenty of engineered things could be "better" if price wasn't a concern. Most of this board can probably think back to a time where they had to leave long term value on the table because of short term costs concerns. It doesn't seem impossible to me that the engineers would leave some battery longevity (something that's hard to gauge for the consumer) on the table in pursuit of faster charging speed at lower prices (headline marketing items).
- jve 2y ago
  And because of this, electric vehicle manufacturers should take note. If only for a city only car that you mostly charge at home, don't do roadtrips with multiple fast charges in short period of time you may get away with passive cooling. And if you don't live in a hot climate. But those are too many IFs.
  - sokoloff 2y ago
    That describes our use case pretty well (for a 2-car household) and we’ve been quite happy with the 26K miles we put on our Nissan LEAF in MA over a coming up on 10 year period. Charged at home >50% of the time and pre-pandemic on the 6.6kW chargers at work. I can only recall one attempt we made at a beyond single battery trip, using an EVGo DC charger at the mid-point. I can say it worked, but subsequent trips to that same location were in the ICE car, so take of that what you will. The car is now 80+% charged at home and is a city/nearby suburb runabout (and used for more trips, albeit not more miles, than the other ICE/hybrid). It still has about 85% of its original battery capacity, which means we charge it about once a week, which works just fine for us.

Joel_Mckay 2y ago

Agreed, the study summary needs better explanation to justify the contradiction with dozens of other lab tests. We have several boxes of 21700 cells from various manufacturers (Samsung/Sony/Panasonic) undergoing aging trials for over 2 years now. All LiIon and LiPol chemistries have shown the following: 1. deep-cycle discharges below 60% full cuts usable charge cycle counts from 8000 to under 2000 uses. 2. high-current discharge or rapid-charging accelerates capacity losses by about 15% a year 3. Internal resistance goes up as dendrite defect shorts damage the cell. Additionally, the self-discharge rates increase as the cell is degraded. Very surprising if the technique works for all cell chemistries. =3

gamblor956 2y ago
There isn't a contradiction. This study solely focuses on the very first charge. It doesn't claim that recharging at high currents benefits battery life, only that the first charge at high current forms a larger protective barrier than a first charge at a low current. Other studies have shown that a larger protective barrier improves lifespan. (See other comments on this thread for more details on the science.)
- Joel_Mckay 2y ago
  Some early Microchip LiIon chargers did not split the cycle into 3 to 4 stages (pre-prep, CC-prep, and CV rapid charge). i.e. they would drop into a constant-voltage rapid charge mode assuming the cell was prepped already. None of these systems showed any sort of increased capacity or longevity. Quite the contrary results, this is why the new study details are rather intriguing. =3
  - gamblor956 2y ago
    The problem was probably the pre prep stage.... that appears to count as the first charge as it is defined in this newer study. When they say "very first" they mean it very literally.
    - 2y ago

oska 2y ago

The analogy they use in the article is all sorts of dodgy too : > Removing more lithium ions up front is a bit like scooping water out of a full bucket before carrying it, Cui said. The extra headspace in the bucket decreases the amount of water splashing out along the way. In similar fashion, deactivating more lithium ions during SEI formation frees up headspace in the positive electrode and allows the electrode to cycle in a more efficient way, improving subsequent performance.

deleted 2y ago

[deleted]