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Laptop Battery Life

03/25/2017 11:03 PM

Is it necessary to unplug the power cord of a laptop if battery is fully charged?

As my observation and my peer's, unplugging the power cord when the battery is full extends life of the battery.

Are there not any good design on this? To automatically open charging circuit when battery is full? Or is it intended as market strategy to buy another set of battery?

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#1

Re: Laptop Battery Life

03/25/2017 11:53 PM

It depends on the charging circuit design of your laptop. Many will internally disconnect.

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#2

Re: Laptop Battery Life

03/26/2017 12:23 AM

I've had mine plugged in for about 5 years now, rarely disconnect it to go portable...

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#8
In reply to #2

Re: Laptop Battery Life

03/26/2017 10:00 PM

Same here, mine sits next to my easy chair plugs in. I occasionally take it somewhere for a few minutes unplugged, so I have no idea what its battery capacity is.

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#12
In reply to #2

Re: Laptop Battery Life

03/27/2017 4:26 AM

The one I have at work is like that. The last one stayed plugged in for about three years, so, with the new one I decided just not to fit the battery. At least I will be able to rely on it if I ever do need to take it on site.

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#3

Re: Laptop Battery Life

03/26/2017 3:14 AM

Dear Mr. gutmonarch,

It is true that the battery should not be overcharged. The latest system of design will disconnect the input power once the battery is fully charged so that the battery charging does not occur.

What I suggest is you pl. provide an external switch for the power card with 3 pin plug socket arrangement and use this for charging. Once the charging is done - pl. use the switch to cut off the supply and you need not remove the cable either at your laptop or remove the plug.

We have the option for setting the indicating/ warning alarm when the laptop battery charge falls to the set value. Once the indication/alatm is heard, pl. simply switch on the power supply.

I am following this and by this way we can extend the life of the battery.

DHAYANANDHAN.S

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#4

Re: Laptop Battery Life

03/26/2017 3:17 AM

That is actually a good question. Although I do not think you need to unplug a modern laptop to keep your battery life, I will be able to give you a definitive answer in a few years. I bought 2 identical 17", quad core, HP laptops for my kids at Christmas. My son always has his plugged in, hardly ever draining the battery, my daughter however, is more mobile with hers, only plugs it in when the battery is getting low. If I had to guess, I would think my sons is going to last longer.

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#9
In reply to #4

Re: Laptop Battery Life

03/26/2017 11:03 PM

I would expect the other way around. There is a similar discussion on the battery life of Li ion power tools and people wonder why the spare battery never lasts as long as the original, and this seems to be because people tend to keep the spare fully charged and use the original. Maximum battery longevity is achieved when stored at 40% capacity, not fully charged (as per lead acid batteries). So the original battery, even though it is cycled more, ends up with a longer life because it is not kept in the fully charged state.

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#10
In reply to #9

Re: Laptop Battery Life

03/27/2017 12:26 AM

I've read the same thing. Keeping a Li Ion battery fully charged isn't good for it.

The other determining factor is heat. When a laptop is mobile, it's more susceptible to heat. Sitting in a hot car, or in direct sunlight. The effect of not being fully charge all the time will be offset by the environmental aspects.

Lastly, we do need to factor in the number or charge cycles a Li Ion battery will last. I've read 500 cycles or three years for a daily use cell phone.

The instructions of my Asus tablet says that I should disconnect the charger after the device reaches 100% charge. Ditto for my cell phone.

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#15
In reply to #9

Re: Laptop Battery Life

03/27/2017 9:59 AM

I keep my power tool batteries in my truck in the fully charged state, but I also rotate each one into service as they get used. I put the recharged one in the door on the right hand side of the pocket, and pull a "fresh" one from the left hand side. I also mark a date on them when they were purchased so I know which ones are getting old.

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#21
In reply to #9

Re: Laptop Battery Life

03/27/2017 1:18 PM

Actually, keeping an LA battery fully charged does not give it the best life, also, once you are over 70% of charge, the battery is VERY inefficient as well....

This is why the chargers I make for myself and friends, only charge LA batteries to 70%. There is a switch for a full charge if going mobile for a time.

These are used on Deep discharge leisure batteries and the one I am using still, was bought in 2004.....and is still going strong!!

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#19
In reply to #4

Re: Laptop Battery Life

03/27/2017 1:11 PM

I have the opposite opinion!

Let us know what finally happens please.....

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#25
In reply to #19

Re: Laptop Battery Life

03/29/2017 4:28 PM

Like I said, it was a guess, and these laptops are only 4 months old, and I hope I can't give you an answer for quite some time. They are also used very differently, my daughter plays games on hers, videos, music, movies, all power hungry stuff, my son uses his mostly for homework, some gaming when I kick him off the X-box One. My daughter has completely killed her battery multiple times, the lowest I have seen my sons is about 40%.

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#5

Re: Laptop Battery Life

03/26/2017 7:26 AM

It's more a safety concern. Lithium charging circuits are designed to not overcharge, but if this circuit is damaged or of very poor quality, it may fail. This is rare, but has resulted in some fires from cheap hoverboards.

From Battery University:

"What every battery user should know

A major concern arises if static electricity or a faulty charger has destroyed the battery's protection circuit. Such damage can permanently fuse the solid-state switches in an ON position without the user knowing. A battery with a faulty protection circuit may function normally but does not provide protection against abuse.
Another safety issue is cold temperature charging. Consumer grade lithium-ion batteries cannot be charged below 0°C (32°F). Although the packs appear to be charging normally, plating of metallic lithium occurs on the anode while on a sub-freezing charge. The plating is permanent and cannot be removed. If done repeatedly, such damage can compromise the safety of the pack. The battery will become more vulnerable to failure if subjected to impact, crush or high rate charging.
Asia produces many non-brand replacement batteries that are popular with cell phone users because of low price. Many of these batteries don't provide the same high safety standard as the main brand equivalent. A wise shopper spends a little more and replaces the battery with an approved model. Figure 1 shows a cell phone that was destroyed while charging in a car. The owner believes that a no-name pack caused the destruction.

Figure 2: A cell phone with a no-brand battery that vented with flame while charging in the back of a car.
To prevent the infiltration of unsafe packs on the market, most manufacturers sell lithium-ion cells only to approved battery pack assemblers. The inclusion of an approved safety circuit is part of the purchasing requirement. This makes it difficult for a hobbyist to purchase single lithium-ion cells off-the-shelf in a store. The hobbyist will have no other choice than to revert to nickel-based batteries. I would caution against using an unidentified lithium-ion battery from an Asian source, if such cells is available.
The safety precaution is especially critical on larger batteries, such as laptop packs. The hazard is so much greater than on a small cell phone battery if something goes wrong. For this reason, many laptop manufacturers secure their batteries with a secret code that only the matching computer can access. This prevents non-brand-name batteries from flooding the market. The drawback is a higher price for the replacement battery. Readers of www.BatteryUniversity.com often ask me for a source of cheap laptop batteries. I have to disappoint the shoppers by directing them to the original vendor for a brand name pack.
Considering the number of lithium-ion batteries used on the market, this energy storage system has caused little harm in terms of damage and personal injury. In spite of the good record, its safety is a hot topic that gets high media attention, even on a minor mishap. This caution is good for the consumer because we will be assured that this popular energy storage device is safe. After the recall of Dell and Apple laptop batteries, cell manufacturers will not only try packing more energy into the pack but will attempt to make it more bulletproof. "

http://batteryuniversity.com/learn/archive/lithium_ion_safety_concerns

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#6
In reply to #5

Re: Laptop Battery Life

03/26/2017 7:40 AM

I agree with this report from Battery University with one small exception. A well designed and fabricated charge circuit should easily handle many times the nominal static electricity levels found in the hottest and driest conditions, short of a direct lightning strike. However, if one removes the primary static shield of the case then anything can happen.

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#11
In reply to #5

Re: Laptop Battery Life

03/27/2017 12:28 AM

I remember reading some time ago that Li Ion batteries should not be left on the charger, because a short circuit in the battery may cause it to explode.

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#20
In reply to #5

Re: Laptop Battery Life

03/27/2017 1:13 PM

GA

Great post, many thanks....

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#7

Re: Laptop Battery Life

03/26/2017 4:04 PM

If you buy a new battery, It will us usualy come with detailed instructions on 'conditioning' it. That comes down to fully charging, the once in a while draining it.

Running the laptop on battery alone will get you a few hours. That's not much use for many people, and topping up will probably shorten it's life.

Last time I purchased a laptop battery, it had something like 10 pages of detail. Save the pain and just buy a new one every year or two.

For what it's worth, I keep my laptops on charge when in use. There is some sophistcated circuitry in those things to prevent overcharging etc.

You may get a better answer if you mention computer and battery model. The things vary and one of our jolly group may know first hand.

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#13

Re: Laptop Battery Life

03/27/2017 9:15 AM

If you got a strong battery you can use the factory supplied charging cable to charge up your battery, then disconnect it when your lap top �� is fully charged.

But if you got a weak battery that seems to go dead quickly then you could get an extension cable and always leave it plugged in.

  1. Just remember to wind it up after draging it around the factory floor.
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#14

Re: Laptop Battery Life

03/27/2017 9:52 AM

The best way to NOT use lithium batteries is to run them down to half power and then pull them out. They will sit happily for months without damage.

If your machine will not let you pull them out, then you have to depend on the internal circuits to maintain them. If you pull the power instead, you can run them down and then reinsert the power to cycle them manually.

They do not have "memory" like NiCad batteries, but they do not like to be overcharged or undercharged. They also like to "rest" between charge and discharge cycles. So, if you run them down all the way, give them a few minutes of rest, charge them up half way, and then pull them or stop charging and store them.

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#26
In reply to #14

Re: Laptop Battery Life

04/01/2017 1:40 AM

Excellent advice! GA to you!

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#27
In reply to #14

Re: Laptop Battery Life

04/01/2017 3:25 AM

Its a very good reason NOT to buy anything where the batteries are so designed not to be replaceable by the user.

I do believe that certain Apple products are so designed (I am told!). So I will never, ever buy Apple products, I don't like their marketing strategy anyway....

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#28
In reply to #27

Re: Laptop Battery Life

04/01/2017 11:07 AM

I think you may know that I've been using Apple products for about 37 years, and servicing them for nearly all of those years. I have always been opposed to the way they do indeed make their products difficult to impossible for the user to service. I pay no attention to their marketing strategy, but I keep on using them because they are so reliable and work so well and intuitively!

I'm glad I don't depend on my Mac servicing skills for income, because they rarely have hardware problems. If it weren't for liquid spills, pet problems, and dropped devices, I think our local Apple-Certified repair shop would be out of business!

Yes, the MacBook Pro I'm typing on does require a special screwdriver (which I have) for replacement of its battery. On the other hand, my experiences replacing other people's laptop batteries in recent years has led me to always recommend the official Apple replacements. The third-party replacement batteries cost about half as much, and last about 1/3 as long. I don't believe I've needed to replace any of my own laptop batteries since the turn of the century. When used regularly, as mine are, the batteries last as long as the computers remain useful for my current CAD software; then I get a new computer.

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#16

Re: Laptop Battery Life

03/27/2017 10:32 AM

Once in a while batteries need to be fully discharged and then recharged to increase their life span. I observed this with emergency exit lights. I am not sure whether that is right on laptops too.

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#17

Re: Laptop Battery Life

03/27/2017 11:29 AM

My HP seems to know when it is charged, as the transformer pack in the middle of the power cord assembly, cools of rapidly after the notice of 100% charged appears on the home page. Some do have a shut down mechanism.

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#18

Re: Laptop Battery Life

03/27/2017 1:10 PM

Is it necessary to unplug the power cord of a laptop if battery is fully charged?

Yes if you want it to last a reasonable length of time, as usually the batteries have a far shorter guarantee than the rest of the laptop......

As my observation and my peer's, unplugging the power cord when the battery is full extends life of the battery.

True, but what REALLY extends the life of the battery is to say charge it to 20%, then switch off and remove it. Do this every 3 - 5 months, depending on how much charge remains. Only charge the battery to full, when going "OFF" the mains......

Are there not any good design on this? To automatically open charging circuit when battery is full? Or is it intended as market strategy to buy another set of battery?

I suspect there are some good circuits, but how does one find it out?

Never forget that each and every battery in Laptops, has a specific number of recharges. Just how many, you will only know when it fails, assuming you counted!

A "charge" is ANY tiny or large charge, even if only for a few seconds.....I generally assume between 1000 and 3000 charges....but the number is reliant on many variables, and two identical laptops, with two identical batteries, could have vastly different length of life and the number of possible recharges....

Leaving it always in and on charge, drastically reduces the length of life in my experience....

Its best to only "use" a battery when REALLY needed.....rather than finding out that the charging circuity is poorly designed!! It might fail when you REALLY need it, as no one can predict accurately when it will lose a cell.........

I have an old 486 "Toshie", that I must have had since 20 years ago (guessing!), the battery is still working the last time I used it about a year ago......I have an older version of Eagle CAD that I occasionally need......It only has a hard disk and a floppy...no USB!!

The battery is original!!

Then even if you don't mind buying new batteries from time to time, there is the danger that you might even buy one that catches fire unexpectedly, as has happened to many, even well known makers (Sony for example) have had the problems....

If the replacement is not OEM, you will have to buy a new Laptop yourself, after the fire of course.....

Also, never forget that a battery consists of cells. There is one cell that is the "strongest", it needs a longer charge and gives a longer discharge.

One cell is the weakest. It usually only needs a shorter charge, but does not store as much as the stronger cell.

Most of the chargers do not take this into account, so to get the best average charge, the weaker cell gets "over driven" and fails first.....now the whole battery is defective, just because of one cell.

This is true of any battery of any type, where the cells are not charged according to their needs.....even LA batteries have this problem......

My AA and AAA charger, charges each cell individually, this gives the best average life. Also, I do not run them to fully empty either, that is also what kills a LA battery, other than ones designed for deep discharge of course!

I hope this helps.

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#22

Re: Laptop Battery Life

03/27/2017 10:24 PM

The practice of unplugging the battery when fully charged, then draining them completely before recharging, is a remnant of the days of NiMH batteries that would developed a "memory" as mentioned by deefburger earlier. People were told to do that so they continue to, not understanding that it's no longer necessary.

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#23
In reply to #22

Re: Laptop Battery Life

03/28/2017 12:12 AM

Agreed, except that the problem didn't originate with NiMH batteries, but rather with NiCd batteries.

All Mac Laptops have had lights on the charging cables for at least a decade. Amber indicates charging, Green indicates full charge (not currently charging). The signals that control those lights come from the computer's charging control circuitry, not from the charger.

I've been repairing Macs for about 30 years, and virtually all of the laptops I've seen that had premature battery failure were ones that had been left plugged in 24/7, so the batteries were never used. I use mine on battery very regularly, and yes, the run time does get shorter as the years pass by, but my almost-5-year-old MacBook Pro still gets between 3 and 4 hours on a charge.

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#24
In reply to #22

Re: Laptop Battery Life

03/28/2017 5:00 AM

Actually, there is a bit of a story to that, it turns out this was first noticed when using them in Satellites, quite some time ago. They were being exactly charged (by sunlight sensitive cells) at exactly the same time each and every day.....

It rarely happens when being normally used here on Terra Firma....but many still believe it!!

See here:- Nickel_cadmium_battery

Where you can read:-

Memory effect

Ni–Cd batteries may suffer from a "memory effect" if they are discharged and recharged to the same state of charge hundreds of times. The apparent symptom is that the battery "remembers" the point in its charge cycle where recharging began and during subsequent use suffers a sudden drop in voltage at that point, as if the battery had been discharged. The capacity of the battery is not actually reduced substantially.

BUT! If they do get a little bit low on capacity, a modern charger that "reforms" (I think that is the correct word!!) them, soon gets rid of that!!

There are even chargers that will charge and discharge to recover capacity many times over.....

The main problem appears to be metal particles growing in the battery, that eventually shorts them out, but a stiff jolt of say 12 volts,will usually clear that for a time....they are usually old at that point anyway....

Since using chargers that reform, I must say that generally speaking, AA & AAA of both NICAD and other (NIMH) types, battery life has probably more than doubled for me, except where I bough TOO cheaply.........

Capacity has also steadily improved too....

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