Is keeping laptop plugged @ 100% bad for longevity of battery?

Hey all, i just bought a Zenbook UX32LN ultrabook and since it's a built in battery, i really wanna maximize the longevity of it (hopefully 3-4 years atleast!) It seems unanimous from all the googling i've done that dropping below 10% battery life is bad for newer lithium-ion based batteries. so that's done.

However, there seems to be alot of contradictory articles about if we should keep them plugged in @ 100% or only letting them hit 80%. My friends Samsung Ultrabook has an option to stop charging at 80% as that's apparently the optimum level for the battery and it won't degenerate as quick over the years. I also read that Apple also recommended not surpassing 80%, but that their battery chargers actually report 100% when its really 80%, so they have circumvented that problem. Other articles also said the battery should always be between 40-80% charged to maximize longevity. Which is true? if the 40-80 rule is true, wouldn't i just be charging and recharging constantly instead of just letting it go from 100% to 10-20%?

here's the original article about the 40-80 rule:

Keeping Your Laptop Plugged in All the Time Will Kill Its Battery Faster | Gadget Lab | WIRED

and another saying u can just leave it plugged in all the time with no worries:

Top 5 laptop battery myths - which did you believe?

again, many others argue for both, so which is it in 2014 models? thank you for any insight u guys might have!

 

Laptop batteries have failsafe circuits built into them. They know when to cut off charging and when to take in charge. Keeping the laptop plugged in will not harm your battery in any way. Battery degradation will occur when cells age and release the stored electrons faster. You are wasting your time looking up material about maintaining batteries when the material would apply to removable batteries that you could store away and the run the device without one. All those instructions simply don't apply to your situation. Leaving a battery charged to a certain intermediate amount can make the discharged cells inactive as they require a certain amount of threshold charge to keep them active. Once again, nothing for you to worry about. Every battery is rated for a certain number of cycles. A cycle would be a Complete Charge of 100% to a complete discharge to near zero and recharge to 100%. Good quality batteries last for a minimum of 400 cycles and above while the generic ones last for about 100 to 200 cycles even if the ratings are lower.

This has worked for all my laptops. I have a 7 year old Sony whose original battery died after 5 years. It was continually plugged in.

Keep the device plugged in and forget about the battery. If you are still worried, unplug your laptop once in a while (couple weeks or a month) and run it down to about 20% and charge it back up. Keep the laptop away from extreme heat or extreme cold environments. Extreme temperatures promote degradation of the battery. You have to remember that the laptop itself generates heat that is close to the battery. The manufacturer has taken extreme care in their selection of materials that gives you the best possible performance without hurting their bottom line.

Good luck with your laptop. Enjoy it.

My 2 cents.

 

It does reduce the life of the battery but not for the reason you think. Lets cut through some of the contradictory crap shall we?

OK, lets break down the factors that reduce the life of a battery:

1. Heat: The biggest factor, basically, for every 20 degrees of extra heat the battery is forced to operate in, you can permanently lose up to 10% (if the battery is at 40%) or 25% (if the battery is at 100%) of maximum charge. Too much heat and the battery essentially explodes.

2. Storage voltage: Batteries do not output a continuous voltage, a single cell usually has a nominal voltage of 3.85-4.3V (I.e. laptops tend to have multiples of these cells in series to deliver 12V, and several of these units in parallel in order to deliver the current required) from 50%-100% charge level. Cells that are forced to be stored at 4.3V degrade much faster than ones that are stored at 3.85V, you get double the number of recharge/discharge cycles for every .10V less the battery is stored at. This is the reason high quality, long lasting and continuous voltage batteries are so expensive and heavy, you literally have to overprovision on the number of cells. For example, an el-cheapo unit may only have banks of 3 cells in series to deliver 12V so thus the cells are forced to be stored at 100-110% (i.e max voltage), a high quality unit may use 4 or even 5 cells in series but each at a reduced voltage in order to deliver 12V so thus each cell is stored at well below 100%.You typically only see this kind of overprovisioning with medical units or other batteries that cannot be readily changed.

3. Discharge depth: batteries are typically rated on how many 100% discharge cycles are performed, the reason for this is that you get buildup at the anodes every time you discharge. Therefore, if you only discharge 50% and then you top up, you will roughly double you maximum number of discharge cycles.

4: Rate of charge/discharge: Fast/high current charging/discharge reduces the life of the battery, again this is because it encourages the buildup at the cathode/anode in addition to heat being produced. Heat accelerates buildup formation.

All these factors are synergistic.
Now back to the question, why does keeping it plugged in reduce the discharge cycles?. Assuming the battery in question has protection circuits which prevent over charging (this is practically mandatory with all Lithium Ion units to prevent fires).

1. People who plug in the laptop tend to use it for high performance applications. This produces a lot of heat which is then transferred to the battery. Heat reduces the life of the battery. A good laptop design would account for this and insulate the battery + isolate the CPU/GPU from the power delivery area. Ultrabooks, tablets and phones don't have this luxury of isolation so they tend to suffer this degradation the most, thankfully, manufacturers also tend to use the best possible cells for these applications.

2. Pretty much self explanatory, constant charging forces the battery to be stored at a high % thus higher voltage. This is where the recommendation, for 80% storage (presumably enforced by software) for normal applications and 40% for long life, came from.

3. Not very applicable for the issue of constant charging but it can play a role if the power delivery was poorly designed. Some manufacturers (cough, Acer, cough) grossly underspecc their Power delivery systems so under extreme stress, power is drawn from the battery to assist the power brick. Basically, in a plugged in scenario, the battery is continuously being charged and discharged, while this doesn't hurt too badly since the depth of discharge is small, the constant switching means the battery is continuously operating, this means heat is being produced internally. Heat is bad for Lithium Ion.

4. See number 3.

All of the above being said, most manufacturers do use high quality, well insulated cells with decent regulators for their OEM original units so it isn't as bad but the same standards don't apply to replacement/cheapo units. There is a reason why good quality units cost >$200.

So this hopefully cuts through some of the crap and misinformation out there.
Further reading from a very reliable academic source (most of my information was from here):
How to Prolong Lithium-based Batteries - Battery University

 

What do you plan on using the battery for and how long (per charge) do you need it to last?

Leaving the battery plugged in all the time will reduce its ability to hold a charge, but the extent to which such ability is reduced is dependent on a number of other factors, including the age of the battery, how hot it gets on a regular basis, and how many charge cycles it's designed for and have been used, in addition to the specific chemistry in that particular battery. So while leaving it plugged in all the time isn't good for the battery, it's not necessarily going to be the cause of its premature death.

My question about your battery use will help let you know what your answer is. If you intend to use your battery as a backup universal power supply, then leaving it plugged in is probably not going to kill the battery entirely for a few years. You'll probably have only 20-30 minutes of battery life after a few years, but that will be enough to safely power down the system. On the other hand, if you plan to occasionally take the computer to seminars where you will need long battery life as possible, you definitely want to be periodically (say once a week) discharging the battery some to ensure you have maximum battery life for as long as possible.

If you already have a UPS, then I would advise discharging the battery to around 40%, taking it out of the system, storing it in a cool room (say a pantry or closet) and putting it back in and charging it up again when you next plan to use it. This will allow the battery to last as long as possible. And if you plan to be using the battery at least a few times a month, then don't worry about any of this and just use the system as you normally would. Typically, batteries do not simply die; they progressively lose a charge. As an example, the battery on my Thinkpad W530 that initially lasted 8 hours on a charge 2 years ago will now only last 5 and a half hours on a charge. That's still an acceptable amount of battery life for me, so I don't need to get a new battery, although I will probably have to at some point. When your battery starts lasting less than what you need, on a regular basis, then it's time to buy a new one.

As a side note about maintaining battery charge percentages of lower than 100%, one of my all-time favorite pieces of software is something Lenovo issues with Thinkpads running Windows 7. It's called Power Manager, and it allows the user to customize the exact charge characteristics of the battery. So, if I used my computer constantly plugged in, then I could set up Power Manager to set the minimum charge threshold at 40% and the maximum at 60% and thus maintain my battery for longer. I wish there were more programs that had this sort of functionality.

 

Simple Answer: No!
.......

Why people are so concerned about this is beyond me. No, it will not degrade your battery anything significant. Just plug it in, use it, and enjoy it. Biggest battery killers are heat and draining and recharging to any level. Leaving your laptop in a hot car or backpack is significantly more detrimental than charging to 100% and leaving it plugged in. If you need a new one in 2-3 years, buy one for $50-60. If you're concerned about saving a couple percent battery life a year, then nurture it and manage it delicately. But you'll still lose battery life, and at most 2-3% more if you just plug it in and go. But it really is irrelevant over the life of the laptop.

 

The reason why the OP is so concerned is because it's a sealed battery - he or she can't just buy one for $50-60 in 2-3 years (it's not easy finding replacements for non-Apple custom batteries years after the product has been discontinued, and that's assuming the OP is willing to open up the system in the first place) - once the battery is gone, that laptop is finished.

 

Ok, then perhaps it isn't the wisest choice of notebook if it is a concern. Honestly there will be a very small % difference whether you charge fully or not.

Also, as far as batteries, this search seems to say otherwise: https://www.google.com/search?q=asu...OjyAS_6oHwBQ&ved=0CAgQ_AUoAQ&biw=1507&bih=906

$60-80 for a replacement. By the time it needs to be replaced, warranty will be void, so not opening it for that concern is moot.

 

My battery lasted for more than 6 years in my old laptop.

 

My observations:

1. Availability of replacement batteries improves when notebooks are around 3 years old and the 3rd party battery specialists see the demand for replacement batteries increasing.

2. Avoiding fully draining the battery to reduce wear has already been identified. Wear also occurs when trying to fully charge the battery. Most / all notebooks stop charging the battery once it reaches 100% and won't start recharging until the charge has dropped.

3.If you can leave a notebook continuously plugged in the the battery won't suffer. The worst usage is depletion during the day and recharge overnight. This may be a necessary scenario for some users but I've come across people who think a daily depletion is good for the battery (perhaps some left-over thinking from nickel-based batteries which need to be drained.

4. Samsung's battery life extender option (which they discontinued about a year ago) which limits the charge to 80% helps because it avoids the full charging. Both Dell and Lenovo provide quite sophisticated power management software with their business notebooks (I'm not sure about their other models).

John

 

Thank you for all your replies very insightful!

OK, let me explain my laptop usage then to paint a better picture. I bought an ultrabook for its light weight and high specs. I have a very powerful desktop and use that for pretty much everything (4.4ghz i7 with SLI & 16gb of RAM for video editing, gaming, and photoshop). twice a year i travel for 1 month at a time & during those 2 months i don't have access to my laptop and will do everything on my ultrabook. eg writing documents, surfing the net, watching HD movies, and light gaming. during those 2 months of travelling i often go to starbucks to use their free wifi, so i would like my ultrabook to last 4-6 hours on battery mode. when i do light gaming it would be in my apartment or hotel. again, this is for only 2 months of the year when im doing all my travelling (february & august). the rest of the year i use my desktop.

so, marksman30k, for intensive applications (like HD movie watching and light gaming) i shouldn't keep it plugged in to avoid voltage fluctuations and ideally would do such activities in the 40-80% battery range to minimize heat output? This is a highend 2014 zenbook ux32ln ultrabook, doesn't it have built in circuitry to manage voltage delivery and protect the internals from too much heat exposure?

 

Please use the laptop any way you wish to. It shouldn't matter. The vents are placed away from the battery any way. All you need to keep in mind is to keep the laptop on a flat surface which doesn't block the vents (Your lap is not a flat surface). Hot air away from the laptop is good. A lap desk would help a lot too if you find yourself using it in such a way often.

I believe in the KISS principle and apply it wherever I can.

 

Built in, but replaceable. Just can't do it on the fly like in the good old days.


from http://forum.notebookreview.com/asus/747849-asus-zenbook-ux32ln-nvidia-gt-840m-3.html

Remove few screws underneath, remove cover, remove few more screws holding the battery and its cable. Replace in reverse order. I'd say 15 minutes.

I wouldn't worry too much. As it has already been said when the battery fails due old age, laptop will be so old that it's out of warranty anyways and you are free to replace battery with a new one without worries.

 

Battery tech has improved a bit in recent years in terms of longevity; most of the built-in batteries nowadays can withstand more charge/discharge cycles than the external removable batteries from a few years back. I wouldn't be too worried about it unless you go through multiple cycles in one day. Keeping your laptop plugged in will be fine.

 

I can't say this is the case for the OP, but many people are adverse to opening up electronics not because it'll void the warranty, but because all those product safety labels have convinced them that they're going to electrocute themselves and their children to death if they try and that you need to be an "authorized service personnel" to safely open a gadget.

 

Looking at your notebook specs, it uses a Lithium Polymer battery.
A couple of characteristics you should know.
1. Reduced endurance vs Lithium Ion (Li Cobalt), you have maybe the same number of cycles as the worst LiCo batteries and maybe half of the very best LiCo cells.
2. Reduced temperature tolerance. I am assuming this means that heat will degrade it faster than the LiCo types.
3. Extremely volatile and especially sensitive to overcharging. This means that your notebook definitely has failsafes built-in. ASUS may have even overprovisioned your battery too just in case.

As for usage:
I don't think keeping it plugged in is a problem since I am very sure your machine has very advanced safety measures due to the relative frailty of Li Polymer batteries. Your biggest enemy is still heat so avoid using on carpet or a bed if possible, the voltage fluctuations shouldn't be an issue if it was correctly planned for. I wouldn't worry about the 40%-80% as much unless you are planning to store the notebook long-term. Instead, I would avoid full discharges if at all possible though bear in mind this is exactly what a battery is meant for.