laptop batteries charging myths - Long life OR short life

Question

I'm very conscious about the life of battery.

Some people say that don't keep plugged-in laptop all over the time and remove battery charging at 70% and again charge at 40% so your battery cells don't charge or discharge at their full position, and battery cells will keep at their optimal voltage rate.

VS

Some of says keep your battery plugged-in all the time so that your battery will not be used by laptop and battery's life cycles will not drain and important this is laptop will stop battery charging automatically when it reached to 100%

Which is true?

Answer 1

The best report on this subject

https://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

The lowest aging rate is known to be 0'C 66% SoC which is the approx. SoC charge level used by OEM's to ship/store LiPo batteries.

Depth of discharge %DoD, greatly affects total lifetime Ah capacity.

             NMC     LiPO4
 100% DoD   ~300    ~600
 80% DoD    ~400    ~900
 60% DoD    ~600    ~1,500
 40% DoD    ~1,000  ~3,000
 20% DoD    ~2,000  ~9,000
 10% DoD    ~6,000  ~15,000

Control depends on laptop OEM and bios + drivers. Lenovo has the best user options for float charge level and slow charge option prior to going mobile to get max capacity. Choose Longest life settings for 70% to 80% float SoC rather than 100%.

"A laptop battery could be prolonged by lowering the charge voltage when connected to the AC grid. To make this feature user-friendly, a device should feature a “Long Life” mode that keeps the battery at 4.05V/cell and offers a SoC of about 80 percent. One hour before traveling, the user requests the “Full Capacity” mode to bring the charge to 4.20V/cell"

Also FYI http://batteryuniversity.com/learn/article/why_mobile_phone_batteries_do_not_last_as_long_as_an_ev_battery

https://batteryuniversity.com/learn/article/rising_internal_resistance

https://www.researchgate.net/publication/303890624_Modeling_of_Lithium-Ion_Battery_Degradation_for_Cell_Life_Assessment

https://batteryuniversity.com/index.php/learn/article/bu_808b_what_causes_li_ion_to_die

Answer 2

You'll find yourself in a situation where both are true.

Point is: the aging processes in your Lithium battery are are dominated by usage (especially: decomposition of the electrolytic carriers, and forming of metal dendrites at high currents). Obviously, not using the battery will avoid these. Lithium Batteries have an excellent shelf life.

Leaving them in the laptop while always powering that, however will not guarantee the battery is never used. That depends on how the charging and powering electronics' firmware in your laptop has been designed.

While not being used, the main aging factor in batteries (of practically all kinds) is osmosis of chemicals through membranes that shouldn't let them through – and osmosis speed goes with the square of concentration difference, which goes linearly with charge. So, for prolonged storage, discharging to somewhere between 40 and 70% does seem a good thing.

But: What use is a stored battery? If you ask me, a battery is "old" when it doesn't have 70% of the original battery life. So, if you force yourself to keep below that charge, great, your life is as bad as that of someone with an "old" battery.

So, seriously, use your battery, and buy electronic devices where the main battery can be exchanged either trivially (Business laptops often have batteries that you can simply click in and out – usage hint: for someone who doesn't need a high-end gaming laptop, a used 3 year old business laptop plus a new battery is often better and cheaper than a new consumer laptop) or are known to be well-replaceable with good replacement batteries (phones, mainly).