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  • linear cannonlinear@nya.social
    Oct 14, 2026, 7:50 PM
    @diazona@techhub.social @nyhan@fediscience.org modern laptop (and smartphone) batteries with lithium chemistries benefit mainly from remaining as close to about 75% charge as possible at all times, preferably not charging above that, and charging slowly instead of quickly. this is why most flagship smartphones and corporate laptops now have options to stop charging the battery when it gets above 80-90% and limiting charging speed

    what @ireneista@adhd.irenes.space described is true of older nickel cadmium (NiCD) battery packs.

    NiMH batteries also exist and are said to have a memory effect, and can exhibit a similar sort of crystallization, but the cause is different. it mostly shows up with any use, regardless of how well you use it. these can, if you are careful, be "shocked" back into a normal condition, but leave this to the people who are experts. this is commonly done by old hybrid vehicle enthusiasts to refresh their battery packs.
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  • linear cannonlinear@nya.social
    Oct 14, 2026, 7:54 PM
    @diazona@techhub.social @nyhan@fediscience.org @ireneista@adhd.irenes.space cycling the battery from 0% to 100% can help with some things with modern lithium battery packs, but most of the time, what this actually is doing is nothing more than calibrating the microcontroller inside the battery pack that tells your computer what percentage charge the battery has

    (the battery estimator, or "fuel gauge" as it is actually called in the industry, is actually really difficult to get right with lithium batteries in particular, so it basically just guesstimates based on two calibration setpoints and how much current the laptop has been drawing)
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  • linear cannonlinear@nya.social
    Oct 14, 2026, 8:04 PM
    @diazona@techhub.social @nyhan@fediscience.org @ireneista@adhd.irenes.space so with the knowledge that the percentage your computer tells you is only a guess, here's what lithium battery cells really like:

    they like being at 3.7 volts. they tolerate being charged as high as 4.2 volts, or discharged as low as 3.2 volts, maybe even 3.0.

    3.7v is very "sticky", though. you can charge it up to 4.2, but it will quickly drop to 3.7 and stay there for a long time, before eventually sharply dropping once it runs out. this is why the fuel gauge has to guess - it's at 3.7v most of the time.

    but the longer and the more it is outside that 3.7v range, and the harder you are driving the battery while it is, the more chemical reactions will happen that reduce its ability to hold charge the next time around.

    so, what you really want to do, to prolong the battery in your laptop as long as possible, is to stay out of those ranges, and keep your battery in the middle. don't let it fully discharge, and don't let it charge all the way up either, if you can help it (but that's better than running it dry)
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  • linear cannonlinear@nya.social
    Oct 14, 2026, 8:30 PM
    @diazona@techhub.social @nyhan@fediscience.org @ireneista@adhd.irenes.space

    for the record, my qualifications:

    i have been shipping industrial and commercial devices with batteries throughout my ~10 year career in embedded device development and have been responsible for making sure those batteries wouldn't blow up in people's cars or pockets or hands. this has not been the main focus of my job, but i have given it the requisite care and research i think such a thing deserves.

    i rebuild laptop battery packs, and my dad rebuilds hybrid car battery packs. i experiment with new battery chemistries as soon as they come out and build my own chargers from them out of spare parts i have lying around. blowing up batteries this way is very easy. i have not blown up a battery since 2016.

    i currently work in the energy field, with people whose specialties are in such things, including things like large grid-scale battery facilities.
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  • Irenes (many)ireneista@irenes.space
    Oct 14, 2026, 7:50 PM

    @linear @diazona @nyhan er

    our understanding is crystals are the limiting thing on all forms of electrochemistry, it's just charging circuitry tries to mitigate the worst scenarios?

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