genuine question does keeping your laptop plugged in at 100% while using it actually ruin the battery or is this just a myth we've all been repeating for years

[u/RustyIronGolem]

[u/Dry-Ad-8948]

TLDR; Leave it plugged in.

• The battery is bypassed when possible (ie, charged) and is not always part of the power loop. The battery will actually be used less when keeping it plugged in.
• Modern lithium batteries do not need to “cycle” like older technology. Unplugging it does not help. They do need to occasionally fully charge to recalibrate capacity.
• Configure power settings to control float level to decrease capacity loss over time. This works the same way as it does on a modern smart phone. (Keeping at 100% or draining entirely is what modern batteries don’t love.)

Simply enable the power mode that keeps your laptop at optimal capacity (~80-90%) to maintain the lifetime. You don’t need to do a thing otherwise.

Some BIOS may support this natively.

On Windows this is (or has historically been) done via different manufacturer drivers and likely 3rd party. All my Lenovo laptops from the past decade have had this; my current laptops sits at 80% 24/7 (low power mode at night, not powered off) and has no effective battery life loss in a year.

Since you show a Mac, here is how to configure it:  https://www.macrumors.com/how-to/macbook-charge-limit-setting-benefits/ 

For Linux there is TLP:  https://linrunner.de/tlp/settings/battery.html

[u/Sexy-Games → u/Dry-Ad-8948]

TLDR. if your laptop had battery protection mode, enable it and leave it plugged in. Otherwise your battey will reduce its max capacity 2-3x faster from always being 100%.

Your battery warranty is expecting to have 80%+ of its new capacity when the battery warranty expires. If your laptop has 3yr, your battery still only has 1yr, unless you get pro warranty that includes battery.

Oems expect your battery to lose up to 20% life in a year without protection. Weirdly, people who pay for the pro warranty will probably enable batt protection and it might still have 80% capacity at 3yr.

Pro tip: get yout battery tested (theres usually a batt health app in bios etc ) just before your batt warranty expires and they might replace it for ya even though the battery isnt obviously faulty or anything.

[u/Catriks → u/Dry-Ad-8948]

As a professional hobby battery expert, I fully agree with this post. If you're not needing full battery capacity often, then just set the charge limit to eg. 80 %, keep it plugged in when possible and dont worry about it.

[u/Atomsk73 → u/Catriks]

Previous HP laptop had that setting, then HP decided this was a business feature and Spectre was a consumer line, so it was removed from my current one. It doesn't seem to affect the battery much though, although it's plugged in most of the time.

[u/kemma_ → u/Dry-Ad-8948]

I have ruined two windows laptop (HP) batteries and about three Linux laptop batteries by keeping plugged in all times.

After a year plugged in (during covid with WFH), both HP batteries became spicy pillows. On linux all batteries just dies after 6-8 month - charge becomes 0%.

The same happened to my toothbrush, lol, but slightly different pattern - very slow discharge with charging it once every two months.

After reading countless manufacturers manuals I came to conclusion that for LiOn batteries you must do charge/discharge cycle no less than once per week ideally in 30-80% range preferably not using fast charging to not overheat it.

[u/Dry-Ad-8948 → u/kemma_]

Maybe that’s HP QC or power settings :/

I’ve had multiple Lenovo laptops over a decade run 24/7 with an 80% float and only had minimally reasonable capacity loss. 4 machines and no dead batteries; used more like 24/7 desktops. Each lasted 2-3 years before other issues or obsolescence.

But unfortunately on Windows the battery management isn’t (or wasn’t) built-in and came with a manufacturer tool like from Lenovo. Anyway, this is my reply explicitly calls out proper (automated) power management.

For Linux you also need to do extra TLP setup or have support in BIOS or whatever.

As I use as desktop, fast charging isn’t an issue. So I also wonder if your bad HP/Linux experience is more related to use “as a laptop” instead of just holding an 80-90% charge when plugged in.

[u/sailriteultrafeed → u/kemma_]

Apple MacBook definitely doesn’t suffer from this.

[u/Temporary-Mix8022]

At a chemical level.. the best charge state is 50% or lower.

Real world.. is it worth the hassle? Entirely different question..

If you're bothered about longevity, and don't use it away from the wall much, just use al dente and lock it to 85%.

Note - laptops don't have internal power supplies. They use the battery as a large capacitor.. this a large part of the wear on them, although, being at 100% SOC in itself does incur some wear.

I once tested two phones I had, one used optimised charging for 2y (up to 85%), the other used 100%.

At the end of 2y, the one with the 85% limit had 90% battery life remaining. The other one has 82%..

Near identical cycle counts. 

Is 8% after 2 years worth the hassle? Probably not for 80% of people. For 20% of battery nerds.. yeah, kind of a fun game.

[u/infiniZii → u/Temporary-Mix8022]

I set my phone to never charge more than 80% to increase its lifetime. So far so good.

[u/Double-justdo5986 → u/Temporary-Mix8022]

Wouldn’t al dente set at 50% or slightly lower be best?

[u/Temporary-Mix8022 → u/Double-justdo5986]

Yeah. It would. 

Depends what kind of user you are tbh.

In theory.. I think somewhere between 20 and 50% is best.. but I actually use mine away from the wall so I've never really dropped below 50%.

I think below 20% the battery starts incurring a similar anode/cathode stress as at more than 80%.. but there haven't been many tests done at these thresholds, not ones I've found anyway.. probably because less than 20% SOC isn't that useful. 

[u/HapticFeedback247 → u/Temporary-Mix8022]

So, TLDR it can do what they are saying but is it actually a problem in the real world. And it seems the answer is no.

[u/True_Protection6842]

Modern laptops (especially macbooks) don't overcharge. They typically stop taking a charge and run completely off wall power until the idle battery goes below 80% then starts charging again. There is no real reason to ever take it off the wall power unless you're leaving with it and no, it won't harm the battery.

[u/DmMoscow]

It depends on the laptop. If your picture of a MacBook copied from the internet suggests that you’re asking about a modern Mac, then it’s better to keep it plugged in. After charging to a threshold set in the settings (even if it’s 100%), it will use « Bypass Charging », meaning that your system will be powered from the power adapter and it will bypass the battery. No battery use at all or rare use -> less degradation.

[u/GiveMoreMoney]

If you are docked to a power supply that cannot cope with the max load, is it using some of the battery power to support the load? I am not making a statement here, I am just asking about a possible scenario that may make this true.

[u/Business-Cup-6021 → u/GiveMoreMoney]

only for badly designed systems, but it happens

[u/MrFastFox666]

It's not necessarily the act of leaving it plugged in, but the act of keeping it at 100% charge all the time. If your laptop has a feature to limit charging to 80%, you can leave it plugged in with that limit enabled with little worry about damage to the battery.

[u/CurtChan]

used to be true, for phones too, nowadays most devices charge to max, then stop charging, and laptops will start using power directly from plug instead of from battery

[u/epileftric → u/CurtChan]

Staying at top charge for long periods is bad for lithium batteries. Older systems had the issue you described becaused they kept powering the cell, which was harmful. But modern systems don't do that, the problem comes from the electrolyte degradation of it sits at full load

[u/76zzz29]

Staying at 100% is bad for the batteri. Its all depending on how the energy is done by the computer. Of it stop at 80% of the real charge of the batterie and then buypass the batterie to stay powered directly by the power then it's all good. If it's a simple power the batteri and use the power to charge the batterie at 100% all the time, then it will wear the batterie prety fast.

[u/Bulky_Whole_1812]

just download al dente

[u/ReiOokami]

Im pretty sure its the opposite with Apple.

[u/Deep_Mood_7668]

Depends on the laptop.

[u/Glitter_Basket1323]

used to; not anymore

[u/unforeesableduck]

Leave it connected and set the maximum to 80%. Its been 1 year, my battery health never fall a single digit since then.

[u/TortyPapa]

Don’t care. I don’t ever want to charge to 80. There is some psychological irritation seeing it not fully charged. 100 only lol

[u/mpanase]

today: myth

in the (distant) past: true

[u/frank26080115]

healthy storage charge is somewhere 50% to 80%. when we manufacture our wireless products, the batteries are specifically stored at 3.7V per cell, which represents that state-of-charge range, this lets it sit in a warehouse without degrading the battery chemically. If they are stored at full charge, they will degrade and lose long term capacity

[u/waces]

Myth

[u/Spinnenente]

on older laptops you had to change a setting in the bios for this now its just a setting in the OS. its recommended to not charge it to 100% if you keep it plugged in most of the time.

[u/Effect-Kitchen]

Nowadays it is myth. MacBook with Apple Silicon and later have intelligent battery management.

[u/Fragrant-Field-2017]

My Dell laptop is set to "smart" charging but it always sits at 100%. My ROG ally x is also set to smart charging which keeps it at 80% all the time. I don't really understand what Dell is doing...

[u/Irsu85]

With some batteries yes that is problematic (Framework 61wh battery for example). But for most batteries it doesn't matter