If we keep a computer charging, does it affect the battery so much that battery-life is greatly shortened?
I am trying to find out why someone else's computer battery always gets bad after a couple of months using it. Is it just education on being aware to remove the plug when batteries are full, or is there any trick to use?
Details
The particular computer is HP, and the battery is Li+. But information about other battery types on this same respect is welcome.
From what I've heard (unsourced, but I'm providing this as an early answer), the ideal behavior... depends on the type of battery.
With Ni-Cad, the best thing was to let them discharge fully before charging again. They suffered from a chemical condition that was often called "memory", as prior actions could affect battery capacity.
Nickle-Metal Hydride didn't have as much issues with "memory", but still discharging them was preferable.
With Lithium-Ion, the best thing is to keep them rather fully charged, at capacity. Fully discharges are detrimental, not beneficial.
With any of these, expect they won't last much longer than years. (Maybe 3-5 years commonly.)
As for what comes after Lithium-Ion, I've heard various things. The correct answer is probably just not solidified yet. Possible advances include wireless charging over some distance, and super-quick charges (which may reduce some need for even having as big of capacity).
Assuming you are using a non-ancient or edge-case laptop it will have some type of Lithium based battery - and my answer makes this assumption.
The worst things for your battery are - in rough order of how stressful they are:
From a longevity point of view, keeping the battery between 40 and 60% charge will increase its lifespan significantly, but will of-course reduce the runtime. (This is why cellphones and laptops are shipped with batteries charged to about 60%) Some laptops have this functionality built into the "BIOS" - including most Dells, and, I think Lenovo's - This would be "the trick" you are looking for.
If you are able to predict when you will need to run it on battery, increasing it to charge close to fully, then running it down is a lot better then leaving it to charge fully overnight - although it is a pain.
Regardless of what you do, the battery will gradually deteriorate. Even unused, the warmer the environment, the faster it will die - but expect it to loose between 2 and 6% per year under normal conditions.
My guess as to why this persons battery keeps dying after a couple of months is that they are allowing the battery to run near or fully flat between charges. (I am assuming they have gone through multiple batteries and its not a faulty battery)
https://batteryuniversity.com/index.php/learn/article/lithium_based_batteries and the pages linked in it are an excellent source of information about Lithium battery characteristics - including results of testing they have done.
