Is leaving laptop constantly plugged in is killing it?

[Aghanim]

Some people say that leaving a laptop constantly charged is killing its battery by overcharging, some say that this problem doesn't exist, some say that to solve this problem you can remove the battery, but others say that removing the battery removes the buffer that protects the motherboard from voltage spikes

There is too many contradictory advice on how to make your laptop battery have longer life, what should I follow?

[Albert VDS]

The laptop(or anyother device) stops charging it when it's full and only uses the power adapter when it's charged.

The biggest problem with any rechargeable battery is that people don't charge it properly.

Disconnecting mid-charge and draining the battery completely are a sure way to kill the battery fast.

When charing a battery make sure it fully charges.

[m4v]

The heat is the principal factor that reduces the useful life of lithium-ion batteries, that's why is recommended to remove the battery when you have the laptop plugged, for keep it away from the heat of the computer, and this damage is exacerbated if you keep the lithium-ion battery at 100% charge all the time. You usually want to avoid keeping the battery at low or full charge for long times. Other factors that influence battery life are fast discharges and charges.

You can't overcharge a battery, the charger logic makes sure of that, and that about protecting the motherboard from voltage spikes is rubbish too.

[bsalis]

As others have pointed out, there will not be any overcharging because of the smart circuitry which has been standard for a long time.

My understanding is that the following will shorten the life of a battery...

* Charge-discharge cycles

* Draining the battery to empty (especially for lead-acids)

* (and obvious things like extreme temperatures, short circuiting it, overcharging, setting it on fire etc)

Which is why for my iPad I do not start charging it until it gets to under half charge, so as to avoid draining it to empty and reduce the charge-discharge cycles.

[Streetwind]

Lithium-ion batteries permanently degrade while operating (charging and discharging). There is a point of lowest degradation somewhere a bit above the middle, and the further you move away from it, the worse the degradation rate gets - exponentially. Discharging below a certain limit is actually worse than overcharging: a single complete discharge can destroy most lithium-ion batteries instantly. This is not unusual for batteries as a whole, which is why there are so many non-rechargable battery types. If you want to get really technical, li-ion batteries aren't truly rechargable either, i.e. you cannot really recover once they drain completely empty.

To combat this, li-ion batteries are equipped with control electronics that keep them within tightly confined operating parameters. For example, the battery in your laptop might be set to only use half of its true capacity, operating in a 30%-80% range. Despite this, the control electronics reports to the laptop "I am at 100%" when the battery is at 80%, and "I am at 0%" when the battery is at 30%. With a setup like this, the upper 20% and the lower 30% of the capacity are never used. The battery stays close to its equilibrium point and thus minimizes its degradation through charging and discharging. When the upper bound is reached, the control electronics stops the energy flow from the charger into the battery, ensuring that no overcharging happens; when the lower bound is reached, the control electronics simply disconnects the battery feed to the consumer, ensuring that no deep discharge happens.

As such, the battery itself does not care in any way, shape or form if you leave your laptop plugged in 24/7. You cannot accidentally overcharge it, the battery controller will prevent it; and as long as the laptop is plugged in, no power will flow out of the battery into the consuming device either. Additionally, recommendations for extending battery life generally involve keeping the battery mostly charged and doing small, short charge cycles - i.e. five times from 80% to 100% degrades the battery less than one time from 0% to 100%. You can take out the battery safely and store it somewhere; this does not harm the battery (so long as it wasn't already empty, which invites further deep discharging through passive energy loss over an extended period of time), but it does not improve its lifetime noticably.

Taking batteries out of devices when plugged in for long periods of time is a recommendation that was valid once, when lithium-ion batteries were in their infancy and the best way to control them hadn't been sussed out yet. Modern batteries (those produced in the last 6-8 years) do not have these issues anymore and you do not need to worry about them.

Anecdote: remember how the original iPhone had a reputation for a quickly degrading battery, which would start out very good but over the course of a year would degrade to a point where the battery had only a fraction of its original capacity and frequently shut down early, even when the phone reported it still had battery life left? Those were the signs of improperly configured control electronics. The controller reported wrong/imprecise information to the device and was set to use a fairly large range of the battery's true capacity in order to achieve any sort of usable battery life for that new, revolutionary but power hungry device. This, combined with the fact that people at the time were used to phones living more than five times as long, frequently let their phones hit 0% and thus required very large charging cycles constantly, led to rapid degradation of the battery cells.

Newer smartphones do this better, but due to the extreme form factor constraints and the tendency of users to "buy and throw away", manufacturers still tend to err towards using large capacity ranges and accepting more rapid degradation than you find in for example laptops or electric cars.

Edited September 23, 2014 by Streetwind

[Red Iron Crown]

I noticed on a Lenovo laptop I recently configured for someone that it had different charge optimization settings. You could choose longest battery life, which would keep it charged to a nominal 100%, or longest battery longevity, which kept it charged at about 70%. I assume that keeping it charged to less than its nominal capacity has some sort of longevity benefit; further evidence of this is the fact that laptop batteries never ship fully charged. I suspect shelf life is greater when shipped at 60-70%.

[rtxoff]

I suspect shelf life is greater when shipped at 60-70%.

That or maybe the self-discharge. Even that li-ion batteries suffer the least amount of self-discharge they are loosing around 2-3% of their charge over a month because of it. Also i am pretty sure that li-ion batteries don't need to be charged afted the production. When they come out of a factory they should have 100% nominal capacity.

[Helix935]

hmm this is why i built a cooling ad for my laptop out of K'nex which included a place to wrap my head phones and a place to wrap my charge cable...

Edit: i am just going to leave this because i consider it brag worthy plus i wish i could engineer rockets as well as the my cooling pad...

just so you know the laptop used to belong to my brother who went to college was rather fond of rubic's cubes which he used the stickers to cover up a scratch

i wish i could engineer my rockets as well as i made this

Edited September 26, 2014 by Helix935

[Streetwind]

I assume that keeping it charged to less than its nominal capacity has some sort of longevity benefit

Yep, as I described above, the more closely you hover around the point of lowest degradation rate, the hgher your battery life expectancy will be. However, the difference between those two settings you mentioned would be unlikely to be very pronounced. Maybe the remaining capacity after five years of constant daily usage will be 33% instead of 25% or something (fantasy values here).

[lajoswinkler]

Yes, if the power management is set to constant 100% charge. It will ruin it in less than one year, and I'm being generous here. Source: experience and general knowledge in the field.

Set the charge limit to 60% or, if your laptop is heating a lot, charge it to 60% and remove the battery and store it at few degrees below room temperature. Every few weeks, plug it in, charge it to 100%, then deplete it to 60%, remove, store. Don't drain it.

[SpaceXray]

I just keep my laptop lugged straight in without the battery at home. When I need to take it somewhere I take the battery with me!

[Camacha]

The laptop(or anyother device) stops charging it when it's full and only uses the power adapter when it's charged.

Most laptops keep topping off the batteries when plugged in, so are in a constant charge/discharge cycle. Some models might not do this, but it is advisable to reduce simultaneous battery and plugin use as much as possible. If you can, remove the battery.

[Nuke]

i do a lot of things with bare cells without control circuitry. never go below 3v or above 4.2v and your batteries will live longer. control and safety circuitry on consumer batteries do this automatically instead of with a multimeter like i do.

[Vallius]

I attended a seminar where the presentation was given by an engineer who manufactures and tests batteries. He advised us that most modern batteries have a much longer life if they are not regularly discharged. In other words, the battery will last much longer if it is kept fully charged and in the laptop when it is plugged in.

If I recall correctly, the practice of fulling charging and discharging batteries is only right for Nickel-cadmium batteries. Most electronics these days use lithium ion batteries.

[lajoswinkler]

I attended a seminar where the presentation was given by an engineer who manufactures and tests batteries. He advised us that most modern batteries have a much longer life if they are not regularly discharged. In other words, the battery will last much longer if it is kept fully charged and in the laptop when it is plugged in.

If I recall correctly, the practice of fulling charging and discharging batteries is only right for Nickel-cadmium batteries. Most electronics these days use lithium ion batteries.

Full charge is not advisable. High charge, yes, but not 100%. Optimum is 3/4 charge at 15-20°C and monthly charge to 100% and then discharge back to 3/4.

The problem is that energy management software or the battery circuitry in many occasions simply doesn't support intelligent management, so it mostly goes 100, 99, 98, 99, 100, 99, 98, 97, 98, 99, 100 - it constantly charges and recharges in the almost full charge. That's lethal, and if the battery is being heated by the lousy heat management (HP, I'm looking at you!), it will drop in capacity in only a few months.

[magnemoe]

Most laptops keep topping off the batteries when plugged in, so are in a constant charge/discharge cycle. Some models might not do this, but it is advisable to reduce simultaneous battery and plugin use as much as possible. If you can, remove the battery.

Still the probably the majority of laptops stand connected most of the time without serious problems, yes it might make the battery last longer, but not very much, has also some downsides like if you forget the battery

[lajoswinkler]

Still the probably the majority of laptops stand connected most of the time without serious problems, yes it might make the battery last longer, but not very much, has also some downsides like if you forget the battery

It will make it last longer, and it won't be a small effect. In worst cases the battery drops to pathetic capacities after less than half a year, in other cases it's fine even after two years or more.

Edited September 24, 2014 by lajoswinkler

[KerbMav]

After installing Linux on my ASUS eeePC - because the whole XP dying and stuff - my battery seems to last longer. Does (inadvisably according to Streetwinds short essay) Linux use more of the batteries capacity or did XP use up more power faster?

[Aghanim]

So, leaving a laptop plugged in constantly is a bad idea because most of the battery management system is stupid?

And related with linux: Sometime when I play fullscreen game the battery is nearly empty notification doesn't come and then the laptop suddenly turns off with a click, is that lethal to my laptop battery? Is there any program that will shutdown my laptop when the battery is nearly empty?

[Debra]

Here's what my techie husband suggested:

- It's perfectly okay to recharge your laptop battery whether it is fully drained or not.

- Leave your laptop plugged into the wall socket whenever possible (like when you are at home).

- It doesn't take longer to recharge the battery if you use the laptop while recharging.

[magnemoe]

So, leaving a laptop plugged in constantly is a bad idea because most of the battery management system is stupid?

And related with linux: Sometime when I play fullscreen game the battery is nearly empty notification doesn't come and then the laptop suddenly turns off with a click, is that lethal to my laptop battery? Is there any program that will shutdown my laptop when the battery is nearly empty?

Not exactly stupid, however it will try to keep your battery pretty filled up in case you unplug it, the charger don't know then you suddenly do so.

And as other say running it dry might reduce life length, however its intended use.

Note that newer Apple laptops without user replaceable batteries has to work well for at lest two years or Apple has to replace them for free in much of Europe.

Reasoning is simple as the battery can not be replaced simple they can not claim its a part who get worn out like tires or chocks on cars.

And no usage patterns are not an issue here.

[Kruleworld]

that's why is recommended to remove the battery when you have the laptop plugged, .

Don't a lot of laptops refuse to start if the battery is removed (and rely on the AC)?