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Serious question: why would I want to do this? In order to prevent my battery from degrading and maybe having 80% its max charge level after some years of use..

Serious question: why would I want to do this? In order to prevent my battery from degrading and maybe having 80% its max charge level after some years of use... I'll proactively never operate at more than 80% charge? How does that make sense?

achierius 1y ago
"and maybe having 80% its max charge level" It's much worse than this. One year can be enough for a 20% drop like that, and it's not impossible to go even lower. Think 50% or worse after 'some years' of aggressive use.
- mikepurvis 1y ago
  Anecdotally this feels like what happens with phone batteries. Apply tells me my battery is at 80% health, but when it's half dead by lunchtime, I'm pretty sure I'm getting more like 50-60% of the original life out of it.
  - gruez 1y ago
    This is probably confounded by the impact of worse optimized software as time goes on, because apps expect faster and more energy efficient chips.
userbinator 1y ago
The degradation-to-charge-percentage curve is highly nonlinear for lion cells. This is why in applications such as aerospace and EVs, they are derated from their original capacity and last much longer.
- kccqzy 1y ago
  This derating is actually really easy to implement: a standard lithium ion cell is actually fully charged at 4.2V, but the battery management system will report it as fully charged once it reaches 4.15V or so.
  - userbinator 1y ago
    For aerospace they only go up to 4.05V, and the cells last tens of thousands of cycles with less than 10% capacity loss after a decade: https://www.nasa.gov/wp-content/uploads/2024/01/saft-ves16-cell-life-test-performance-update.pdf?emrc=65fc803378e2b https://www.nasa.gov/wp-content/uploads/2024/01/saft-ves16-c...
gruez 1y ago
Most of the time you don't need 100% of your battery capacity (eg. at home/office), so charging it to 100% degrades it faster but doesn't provide any benefit. Obviously if you actually need the capacity (eg. you're going on a flight), you'd disable the limit.
- adastra22 1y ago
  Most of the time I do. I don’t leave my laptop plugged in. I use it until it needs a charge, plug it in until it is full, then unplug again. I’m usually not near a charger, so I am actually needing that battery to work. Maybe this is why my experience is different than most here? Still, even after 5 years of doing this, my battery life remains within 80% of its original state.
aunty_helen 1y ago
Neuroticism. Tech people suffer from this condition and need to tinker. Rather than just replacing a well used battery they’re going to spend a lot of mental energy worrying about 15 minutes of charge degradation that apparently they don’t need anyway.
- adastra22 1y ago
  The only answer here that makes sense. Thanks.
mrheosuper 1y ago
Lithium Battery hates being at full state for a long time, that's why when buying new phone/laptop, the SOC you see will never at 100%, usually at 60-70%. Many people leave their laptop plug most of the time, so this harms battery.

achierius 1y ago

"and maybe having 80% its max charge level" It's much worse than this. One year can be enough for a 20% drop like that, and it's not impossible to go even lower. Think 50% or worse after 'some years' of aggressive use.

mikepurvis 1y ago
Anecdotally this feels like what happens with phone batteries. Apply tells me my battery is at 80% health, but when it's half dead by lunchtime, I'm pretty sure I'm getting more like 50-60% of the original life out of it.
- gruez 1y ago
  This is probably confounded by the impact of worse optimized software as time goes on, because apps expect faster and more energy efficient chips.

userbinator 1y ago

The degradation-to-charge-percentage curve is highly nonlinear for lion cells. This is why in applications such as aerospace and EVs, they are derated from their original capacity and last much longer.

kccqzy 1y ago
This derating is actually really easy to implement: a standard lithium ion cell is actually fully charged at 4.2V, but the battery management system will report it as fully charged once it reaches 4.15V or so.
- userbinator 1y ago
  For aerospace they only go up to 4.05V, and the cells last tens of thousands of cycles with less than 10% capacity loss after a decade: https://www.nasa.gov/wp-content/uploads/2024/01/saft-ves16-cell-life-test-performance-update.pdf?emrc=65fc803378e2b https://www.nasa.gov/wp-content/uploads/2024/01/saft-ves16-c...

gruez 1y ago

Most of the time you don't need 100% of your battery capacity (eg. at home/office), so charging it to 100% degrades it faster but doesn't provide any benefit. Obviously if you actually need the capacity (eg. you're going on a flight), you'd disable the limit.

adastra22 1y ago
Most of the time I do. I don’t leave my laptop plugged in. I use it until it needs a charge, plug it in until it is full, then unplug again. I’m usually not near a charger, so I am actually needing that battery to work. Maybe this is why my experience is different than most here? Still, even after 5 years of doing this, my battery life remains within 80% of its original state.

aunty_helen 1y ago

Neuroticism. Tech people suffer from this condition and need to tinker. Rather than just replacing a well used battery they’re going to spend a lot of mental energy worrying about 15 minutes of charge degradation that apparently they don’t need anyway.

adastra22 1y ago
The only answer here that makes sense. Thanks.

mrheosuper 1y ago

Lithium Battery hates being at full state for a long time, that's why when buying new phone/laptop, the SOC you see will never at 100%, usually at 60-70%. Many people leave their laptop plug most of the time, so this harms battery.