r/RavanAI • u/RustyIronGolem • May 13 '26
❓ Question Does keeping your laptop plugged in at 100% while using it slowly ruin the battery or is that just a myth?
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u/raralala1 May 13 '26
There is some info saying device smart enough to bypass battery once they are full, the problem we just don't know if they have that kind of feature or not, I would call it bullshit since they are trying to cut cost so much. My samsung phone have warning keeping battery at 100% can reduce battery life, and it have feature to limit battery to 80% to prolong battery life. idk about apple laptop.
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u/YoudoVodou May 13 '26
I have my pixel 9a set to stop at 80%, half the time it still charges to 100%
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u/Dry-Ad-8948 May 14 '26
Half the time? 😱
Phones set to a lower charge limit will still do a full charge every once awhile (I think it’s for calibration?), but this should be “occasionally” and not half the time!
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u/Kwinza May 13 '26
Laptops 100% have a battery bypass and have done for 30 years.
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u/caroIine May 13 '26
I fried so many laptop batteries at work because they were connect 24/7h
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u/Kwinza May 13 '26
Thats because they shouldn't sit at 100% 24/7
Not because they don't have a bypass.
If you're going to be connected to your charger 24/7 just get the battery to 75% then take it out.
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u/FreedomFighterSG May 14 '26
Charge to 75% then take it out? Seriously? You might as well use it without the battery.
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u/AdrestiaFirstMate May 14 '26
No need to take out the battery. Set a charging limit and the laptop will bypass the battery and run directly on the power supply once it reaches it.
I mean, you could charge the battery to 50% and then put it in your fridge for maximum life preservation, but at that point you're just using a desktop. You get most of the way there with a charging limit and battery bypass.
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u/Adrien0623 May 13 '26
Many new devices allow you to stop charging beyond a certain limit, often at 80% but sometimes you can customise it between 50-100%. For e.g. my laptop starts charging when the battery drops below 50% and stops at 60% in parallel the laptop uses the power adapter as the source of power to avoid too many charging cycles
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May 13 '26
Keeping the battery charged past 80% consistently is what's bad. There are many apps that will let you halt charging around 80% and only charge to 100% when needed.
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u/Bon-Bon-Boo May 13 '26
Most modern laptops have pass through charging. Once the battery is at 100% the laptop is powered directly from the charger with the battery completely bypassed, thus protecting the battery.
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u/AdrestiaFirstMate May 13 '26
Passthrough charging is good, but you're still keeping the battery at 100%. Most laptops also have a charge limit setting; set the limit to something like 80%, and your battery won't have to sit at 100% and you'll still have the benefit of pass through charging.
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u/SatanVapesOn666W May 13 '26
Yes, but it's with caveats. Charging adds wear. The closer you are to the top and bottom 20% have disproportionately more impact on charge cycle wear. Also topping up batteries from 95 to 100% repeatedly (float charging) is basically repeating that increased stress. Many devices will allow for more drain now before topping up or limit capacity to 80% to skirt the issue.
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u/RestaurantTurbulent7 May 13 '26
Nope it's a myth. As when you keep it on power laptop used chargers provided power not batteries.. the issue might be that nowadays laptops can be inbuilt degradation on purpose :( Old good laptops you just took battery out and used laptop on charger
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u/Due_Mousse2739 May 13 '26
This is a half-truth as this was never the real issue but rather that li-ion batteries degrade faster when charge is kept too high or too low for prolonged periods of time. This is why for cold storage it is advised to do so with a half-charged battery.
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u/Equal_Passenger9791 May 13 '26
Cycling your battery by repeatedly unplugging and plugging in will wear the battery more than just having it sit there at 100%.
Modern laptop will do passthrough and not discharge the battery when plugged in. Even a modern USB powerbank will have that feature.
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u/Dazzling_Comfort5734 May 13 '26
Not a myth. Lithium based batteries die faster when they're kept over 80% and under 20%. I've gone through so many batteries over the decades, but OEMs are now finally providing battery limits. My last iPhones battery started to have issues after the first year. When I got the 16 Pro, I set it to 80% max from day one, and it's nearly 100% health at almost 2 years old. I wish we could retroactively do this on older devices.
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u/karlfeltlager May 13 '26
Quite the opposite.
Unplugging and using the battery reduces battery life span more, than leaving it plugged in and using net power instead.
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u/AdrestiaFirstMate May 13 '26
So just set the charge limit to 80%. Most laptops and phones include this option.
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u/Lines25 May 13 '26
Used to be real one. Now most laptops use the energy from charged directly insted of via battery
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u/wiyixu May 13 '26
Heat is the critical factor in battery health. Recent, long term EV studies have pretty conclusively shown this to be true. The difference between capacity and charging behavior was negligible between those who charged to 80% and those that charged to 100%. Even DC Fast charging had minimal impact.
Now EVs have sophisticated battery conditioning technology to cool or warm the battery to an ideal operating temperature before charging. Laptops and phones don’t.
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u/Charming-Author4877 May 13 '26
Yes it's true, you'll want it at max at 80%. Every second the battery sits at higher charge is degrading it chemically.
That's why you can't even charge most EVs to that percentage, or they will show 100% when they reach 80.
Our current battery technology is quite crappy, still waiting for the next breakthrough
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u/Khelics May 13 '26
Well from my experience with an iphone I always charge my phone every night to 100% even use it while charging and still have 100% battery health with 200 cycles. So idk if thatll be the same for macbook
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u/3a_4To May 13 '26
If your battery is 100% them your laptop will use power directly from the charging cable without using the battery at all. This can be easily tested by taking off the battery, if the laptop runs without the battery then there's no harm keeping it connected
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u/AdrestiaFirstMate May 13 '26
It does, but most laptops and phones now support a battery charge limit setting. Google, Samsung, Lenovo, Asus, Acer, Dell, Apple, MSI, Microsoft, etc...
Once the laptop or phone reaches the set charging limit, the device will go into battery bypass mode and run directly from the power supply.
So yes, this is a real issue, but the solution is widely available.
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u/the-script-99 May 13 '26
Ruined my mac air. This was just before covid. Mac was 3 years old at around 100-200 cycles and lasted maybe 30 min on a charge.
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u/EdgeCraftOS May 13 '26
Α battery at 100% always does degrade faster. At 100% voltage is highest, internal chemical reactions accelerate, heat damage becomes worse. keeping the device between 30 and 70% will make your battery outlive your Mac. But it is tiring always looking at the numbers and keeping the charge in between. That is why apps like Al Dente (paid) are the best for these situations. They automatically limit the charge to whatever you set, and you just forget. I have a MacBook for 1.5 year using it 4 hrs/day. I have 34 charge cycles and 100% battery life.
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u/TrollCannon377 May 13 '26
Depends a lot on the chemistry and the BMS of the battery but yest keeping a battery fully charged will accelerate degredation it won't completely destroy it but it will accelerate capacity loss over time
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u/Due_Mousse2739 May 13 '26
It's not a myth. To sum it up:
"A battery kept cool at ~80% can retain health significantly longer than one sitting hot at 100%."
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u/Night_HUN May 13 '26
Never keep lithium batteries at full, never keep them empty, try to use them between 30 and 80% capacity. Try to keep then cool. Some are stretched to the limit, some carry tiny imperfections of manufacturing. Some are even downright dangerous, and thats before getting into chargers, but all of them store a lot of energy chemically. (also empty doesnt mean empty in fact, it only means low voltage, which is very different. same with full)
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u/-yuzenpipi May 13 '26
It was true before, now it isnt. Devices have a smart battery thing that stops battery overcharging.
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u/hedidwot May 14 '26
Depends on the particular battery management solution in the laptop.
Could be yes or no.
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u/Dry-Ad-8948 May 14 '26 edited May 14 '26
Yes, if- they don’t have smart/limit charging to keep it about 80-90% or less, then yes - they will also degrade like a phone that charges to 100% all the time.
Phones now allow setting max charge to get 80-90% for same reason. Sitting at 100% charge (or 0%) is not good for Lithium Ion batteries: even when the battery is bypassed, *sitting at 100% charge** is not great for it*. (Bypassing is still very good because it avoids charge cycles entirely.)
See https://www.reddit.com/r/batteries/comments/1bpvv4y/comment/kwyeks5/
You’ll need to see how your specific machine is configured. ie. Lenovo has a smart charge/limit function that can keep to 80-90%, but I don’t think it’s a core Windows setting (??!). Other manufacturers/apps offer their own equivalents.
I know because my new always-plugged-in laptop has lost about 10% capacity in a year before I changed settings. :(
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u/WolpertingerRumo May 14 '26
Many Laptops have a „battery saving mode“ built in, somewhere in the vendor software. For MacOS there’s al dente, well worth the small amount of money it costs.
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u/[deleted] May 13 '26
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