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.
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
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.)
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
When they say "very first" they mean it very literally.
In general, we track the internal resistance (+-0.02ohm for Samsung) of the inventory under both new, charged, discharging, and storage levels. While I don't doubt the Papers results, they need to be clear on the methodology so others can validate it is not BS (common in this area.)
Have a nice day =3
It is fascinating news, and I look forward to more details. =3
> 1. deep-cycle discharges below 60% full cuts usable charge cycle counts from 8000 to under 2000 uses.
Presumably these are NMC variant?
Major Chinese LFP brands come with 6000K/10K cycle guarantees (but with specific operational parameters). Are these cycle predictions unrealistic ?
catl/eve/etc
That is, if you do it single time you are down from 8k to 2k? Or it decreases gradually and 2k is the worst case?
Where can I read about it? Not a paper, but something more down to earth for consumers? That is, for a consumer to know how to properly maintain various devices (phone/car) for longevity?
That said, I previously read studies suggesting to keep the batteries between 30-70% SOC for optimal longevity, though I imagine there's been a lot of research so it might be now outdated.
In general, "the battery is the car" for EVs... The bigger the better in my opinion, as it will last longer due to reduced stress on the cells.
Even if people are stressing the vehicle pack, they should still get 5 to 12 years out of the car. Note, some companies hide the expected range loss by over-provisioning capacity.
Best regards, =3
This is definitely true, recently faced issues with my motorbike battery and oh boy are they fragile and lose charge by themselves quickly compared to bigger car batteries.
Basically I left a few times older (10-15 years) diesel bmw standing whole winter without touching it, started always without any issue (I know not the best idea re fuel in the tank, but it worked).
I did that once to completely new motorbike (honda) with good brand battery but I didn't unplug it, and now battery is permanently damaged and loses full charge in less than 2 days to such levels that it can't start the engine even if those 2 days its completely unplugged.
Tip: if a Pb pack is partially discharged, it is more vulnerable to cold-weather related standby failures. Most people that own boats/heavy-equipment get a plug-in trickle-charger for Pb batteries, as the adapter also helps keep the pack slightly warmed.
Best of luck, =3
I don't want to get into the name-and-shame game with other manufacturers. The 3 brands mentioned are generally very good quality, and if you can source new cells without counterfeit/expired nonsense... they will perform as per their app notes.
The cycle limit is a function of whether your charger IC is smart, slow-charge/low-current-discharge, and if your firm uses capacity Boosting (stress costs cycle counts.)
>Or it decreases gradually and 2k is the worst case?
Anecdotally, sensitivity seems somewhat correlated with cell use/age. The more stress, and the faster the cell degrades.
Best of luck, =3
https://electrek.co/2023/08/29/tesla-battery-longevity-not-a...
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).
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.
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.
It is healthy to know how to maintain car battery. I will probably charge the battery to ~80% except when I need more range.
It’s down 1 bar (of 12) and that was 2 years ago, so the 85% is estimated, but is within -0% to +4%. I have a LEAF Spy but haven’t checked it a long time.
So: higher voltage implies lower heating.
Energy loss though resistance in the pack's internal wiring is likely a lot less than the loss due to the chemistry not being 100% efficient at absorbing (or delivering) charge without heating up. But it does allow for thinner wires to get max power out of the battery.
There should be less heating for higher voltages but if most if the heating is in the battery vs the distribution system then the higher voltages will not help much.
Also, if they make all wires smaller to save money and weight then there might not be any change in heating.
I think the higher voltage allows them to charge more of the battery pack in parallel at a time.
> 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.