{"id":101699,"date":"2025-11-10T16:00:38","date_gmt":"2025-11-10T21:00:38","guid":{"rendered":"http:\/\/pappp.net\/?guid=bcaef7c555297e942165cec61472d2d9"},"modified":"2025-11-10T16:00:38","modified_gmt":"2025-11-10T21:00:38","slug":"testing-whether-fast-charging-kills-smartphone-batteries-and-other-myths","status":"publish","type":"post","link":"https:\/\/pappp.net\/?p=101699","title":{"rendered":"Testing Whether Fast Charging Kills Smartphone Batteries, and Other Myths"},"content":{"rendered":"<p class=\"syndicated-attribution\">Source: <a href=\"https:\/\/hackaday.com\/2025\/11\/10\/testing-whether-fast-charging-kills-smartphone-batteries-and-other-myths\/\">Hack a Day<\/a><\/p>\n<div style=\"background-color : #fff7d5;\n\t\t\tborder-width : 1px; padding : 5px; border-style : dashed; border-color : #e7d796;margin-bottom : 1em; color : #9a8c59;\">Article note: Dang, I assumed (based on early devices that tended to have thermal issues) that fast charging was meaningfully degrading.  That's nice.<\/div><div><img src=\"https:\/\/hackaday.com\/wp-content\/uploads\/2025\/11\/fast_vs_slow_charging_smartphones_android_htx_studios_youtube.jpg?w=800\" alt=\"\" decoding=\"async\" loading=\"lazy\" srcset=\"https:\/\/hackaday.com\/wp-content\/uploads\/2025\/11\/fast_vs_slow_charging_smartphones_android_htx_studios_youtube.jpg 1359w,https:\/\/hackaday.com\/wp-content\/uploads\/2025\/11\/fast_vs_slow_charging_smartphones_android_htx_studios_youtube.jpg?resize=250,127 250w,https:\/\/hackaday.com\/wp-content\/uploads\/2025\/11\/fast_vs_slow_charging_smartphones_android_htx_studios_youtube.jpg?resize=400,203 400w,https:\/\/hackaday.com\/wp-content\/uploads\/2025\/11\/fast_vs_slow_charging_smartphones_android_htx_studios_youtube.jpg?resize=800,407 800w,https:\/\/hackaday.com\/wp-content\/uploads\/2025\/11\/fast_vs_slow_charging_smartphones_android_htx_studios_youtube.jpg 1359w,https:\/\/hackaday.com\/wp-content\/uploads\/2025\/11\/fast_vs_slow_charging_smartphones_android_htx_studios_youtube.jpg?resize=250,127 250w,https:\/\/hackaday.com\/wp-content\/uploads\/2025\/11\/fast_vs_slow_charging_smartphones_android_htx_studios_youtube.jpg?resize=400,203 400w,https:\/\/hackaday.com\/wp-content\/uploads\/2025\/11\/fast_vs_slow_charging_smartphones_android_htx_studios_youtube.jpg?resize=800,407 800w\" sizes=\"auto, (max-width: 800px) 100vw, 800px\" referrerpolicy=\"no-referrer\"\/><\/div><figure aria-describedby=\"caption-attachment-871644\"><a href=\"https:\/\/hackaday.com\/wp-content\/uploads\/2025\/10\/lithium-ion_cell_calendar_aging_capacity_resistance.png\" rel=\"noopener noreferrer\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/hackaday.com\/wp-content\/uploads\/2025\/10\/lithium-ion_cell_calendar_aging_capacity_resistance.png?w=400\" alt=\"Calendar aging of NMC Li-ion cells at 50 &#8451; at various SoCs. (Credit: Wiljan Vermeer, IEEE, 2021)\" srcset=\"https:\/\/hackaday.com\/wp-content\/uploads\/2025\/10\/lithium-ion_cell_calendar_aging_capacity_resistance.png 550w,https:\/\/hackaday.com\/wp-content\/uploads\/2025\/10\/lithium-ion_cell_calendar_aging_capacity_resistance.png?resize=250,209 250w,https:\/\/hackaday.com\/wp-content\/uploads\/2025\/10\/lithium-ion_cell_calendar_aging_capacity_resistance.png?resize=400,334 400w,https:\/\/hackaday.com\/wp-content\/uploads\/2025\/10\/lithium-ion_cell_calendar_aging_capacity_resistance.png 550w,https:\/\/hackaday.com\/wp-content\/uploads\/2025\/10\/lithium-ion_cell_calendar_aging_capacity_resistance.png?resize=250,209 250w,https:\/\/hackaday.com\/wp-content\/uploads\/2025\/10\/lithium-ion_cell_calendar_aging_capacity_resistance.png?resize=400,334 400w\" sizes=\"auto, (max-width: 400px) 100vw, 400px\" referrerpolicy=\"no-referrer\"\/><\/a><figcaption>Calendar aging of NMC Li-ion cells at 50 &#8451; at various SoCs. (Credit: Wiljan Vermeer, IEEE, 2021)<\/figcaption><\/figure>\n<p>With batteries being such an integral part of smartphones, it&rsquo;s little wonder that extending the period between charging and battery replacement has led to many theories and outright myths about what may affect the lifespan of these lithium-ion batteries. To bust some of them, [HTX Studio] over on YouTube has spent the past two years torturing both themselves and a myriad of <a href=\"https:\/\/www.youtube.com\/watch?v=kLS5Cg_yNdM\"  rel=\"noopener noreferrer\">both iOS and Android phones<\/a> to tease out some real-life data.<\/p>\n<p>After a few false starts with smaller experiments, they settled on an experimental setup involving 40 phones to investigate two claims: first, whether fast charging is worse than slow charging, and second, whether limiting charging to 80% of a battery&rsquo;s capacity will increase its lifespan. This latter group effectively uses only 50% of the capacity, by discharging down to 30% before recharging. A single control phone was left alone without forced charge-discharge cycles.<\/p>\n<p><span><\/span><\/p>\n<p>After 500 charge cycles and 167 days, these three groups (fast, slow, 50%) were examined for remaining battery capacity. As one can see in the above graphic for the Android group and the similar one for iOS in the video, the results are basically what you expect. Li-ion batteries age over time (&lsquo;calendar aging&rsquo;), with temperature and state-of-charge (SoC) affecting the speed of this aging process, as can be seen in the SoC graph from an earlier article that <a href=\"https:\/\/hackaday.com\/2025\/10\/23\/built-in-batteries-a-daft-idea-with-an-uncertain-future\/\" rel=\"noopener noreferrer\">we featured on built-in batteries<\/a>.<\/p>\n<p>It seems that keeping the battery as cool as possible and the SoC as low as possible, along with the number of charge-discharge cycles, will extend its lifespan, but Li-ion batteries are doomed to a very finite lifespan on account of their basic chemistry. This makes these smartphone charging myths both true, but less relevant than one might assume, as over the lifespan of something like a smartphone, it won&rsquo;t make a massive difference.<\/p>\n<p><\/p>","protected":false},"excerpt":{"rendered":"<p>Calendar aging of NMC Li-ion cells at 50 \u2103 at various SoCs. 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