AC usage when battery is at 100% ? (S7-391)

Hi everyone!

I've been experiencing the worse tech-support from Acer, i don't have any problems with the ultrabook itself (Acer Aspire S7-391) but i've some doubts about drivers and stuff, that they avoided to respond in many ways. So here is the thing:

Does this ultrabook has any drivers that could make use of the AC power when battery load reaches 100% to avoid battery weathering?

The thing is that while i've 100% of the battery and the ultrabook is plugged in to the AC power adaptor it still seems to be draining battery power and re-charging it back to be at 100% all the time.

When i ask about drivers, those could or could not be installed, i just need to find out a way to have this feature if possible, and if i can't, i need to know ASAP so i can start unplugging the notebook right after the battery reaches 100%.

Thanks in advance.

Accepted answers

suniljp

As you mentioned with 2 pin power connector can also disconnect the battery from getting charged. It can disconnect the power source from the battery charging circuit when the battery reaches a particular % charge with the laptop running in AC power source. I do not think your laptop support adjusting the battery charging level to a customised %. Your laptop should have a particular hardware and the BIOS should support that. In some laptops the BIOS has the option to set battery charging level to a particular %. I have read somewhere that windows 8 do not support that feature, older version of windows (Vista) support that feature.

Some write up I found online might help you.

Memory Effect

First of all it's necessary to unfold a myth that persists in many peoples head.

The battery memory effect.

In lithium-based batteries this is in fact a myth, it only applies to older Nickle-based batteries. So fully discharging and charging the battery is completely useless and even harmful as we will see below.

The modern lithium battery can be charged regardless of its current percentage, given that it has absolutely no negative effect in its performance.

Should I remove the battery when A/C is plugged in?

Many laptop users have this question and we will answer it right now:

The answer is: YES and NO, it depends on the situation.

Having a battery fully charged and the laptop plugged in is not harmful, because as soon as the charge level reaches 100% the battery stops receiving charging energy and this energy is bypassed directly to the power supply system of the laptop.

However there's a disadvantage in keeping the battery in its socket when the laptop is plugged in, but only if it's currently suffering from excessive heating caused by the laptop hardware.

So:

- In a normal usage, if the laptop doesn't get too hot (CPU and Hard Disk around 40ºC to 50ºC) the battery should remain in the laptop socket;

- In an intensive usage which leads to a large amount of heat produced (i.e. Games, temperatures above 60ºC) the battery should be removed from the socket in order to prevent unwanted heating.

The heat, among the fact that it has 100% of charge, is the great enemy of the lithium battery and not the plug, as many might think so.

Battery discharges

Full battery discharges (until laptop power shutdown, 0%) should be avoided, because this stresses the battery a lot and can even damage it. It's recommended to perform partial discharges to capacity levels of 20~30% and frequent charges, instead of performing a full discharging followed by a full charging.

Laptop batteries contain a capacity gauge that allows us to know the exact amount of energy stored. However, due to the charging/discharging cycles, this sensor tends to be inaccurate overtime.

Some laptops include in their BIOS, tools to recalibrate this battery gauge, which is nothing more than a full discharge followed by a full charge.

So to calibrate the gauge, it should be performed, in every 30 discharge cycles, a full discharge non-stop , followed by a also, non-stop, full charge.

An inaccurate gauge can lead to the fact that the the battery capacity values are are wrong. The battery may report that it still has 10% of capacity when in fact it has a much lower value, and this causes the computer to shutdown unexpectedly.

Discharge (or charge) cycles consist of using all that battery charge (100%) but not necessarily all at once.

For example, you can use the laptop for some minutes in a day, using half its capacity e then fully charge it. If you did the same thing in the next day, it would be counted a discharge cycle and not two, so it may take several days until a full discharge cycle is completed.

All comments

suniljp

Please reffer the below link for the answer

http://acer.custhelp.com/app/answers/detail/a_id/3400/kw/trickle%20charge

How to maintain the battery.

http://acer.custhelp.com/app/answers/detail/a_id/2384/kw/battery%20charging

It’s recommended that once in a week drain the battery and recharge it so this will recondition and will increase the life of the battery. Do not fully discharge the battery as the laptop battery won't charge if the voltage of the battery goes beyond a particular voltage. It need high current charging if the voltage level goes beyond a certain limit.

rAfitiiixxx

Thanks @suniljp for your response, the thing is that the thread you provided a link for, is about a netbook and a diferent model. I've an Acer Aspire S7-391. Do you know if every Acer product has the same features regarding battery? A friend of mine gave me this screenshot of his notebook (another brand but with this feature that i'm not sure if i can have it)

It's written in spanish but it says something like "99% charged (using AC without charging)" Or something similar but equal meaning. While i hover the mouse in mine and it says "100% fully charged" and nothing more. This made me think that my notebook is recharging back all the time while plugged in! Is there any way to know if my ultrabook is at least doing the trickle charge? Is there any driver that will make my S7 use it's AC power only, while connected and over 95% of the charge or similar?

Thanks for your fast response, i will save back that tutorial on how do I maintain and store my ultrabook battery. Hope i can find for what i'm looking for Smiley Happy

suniljp

Does it say 99% plugged in not charging in the picture which you have put up? If so your friend’s laptop battery is not reaching 100 % charge. At 99% it should show reffer the picture attached so your laptop battery is charging perfectly. Most of the modern laptop has a charging circuit which will prevent the battery from over charging and most of the laptop battery has a self-discharge property so the charging circuit will make sure that the battery is always 100% charged. Your laptop is charging perfectly.

rAfitiiixxx

Again, thanks for your great response! indeed, his laptop is showing 99% of charge because it wasn't full at the moment, but he can charge it up to 100% like any other, what i'm saying is that, i don't know if it depends on hardware or software (or firmware) but his laptop can charge as allways but if it reaches 95% or more it won't use the battery energy, instead it will use AC power directly, it's like he could pop out the battery and leave it there, it's plugged but not being used, it's charging but not consuming anything. My lenovo from work (x220) works the same way with a special windows xp driver that you can configure at which capacity of the battery you don't want to use it anymore (if it reaches 95% on default settings it wont run on battery anymore, and run only in AC unless it's unplugged).

So my main problem is not about my ultrabook not charging at 100%. My problem is about a feature, that i've to figure out if it works for this hardware and if not i want to know.

Hope you will understand me Smiley Sad since my english is not perfect.

PS: i've asked him, and re-checked and you can configure if you want your battery to keep charging or not, so his laptop wasn't charging at the moment, and it won't start until his battery reaches 94% Smiley Happy

jonstatt

Do the laptops that have this feature use more than 2 pins from the power adapter to the laptop? Normally the way this feature works, is by providing a 4 pin connection from the power supply to the laptop. This allows one set of power to charge the battery, and the other to provide direct power coupling to the laptop. In the case of the Acer, there is only a 2 pin connection to the laptop.

But to be honest, I am not sure this really makes a difference in preserving battery life. Whether you cut-in at 94% or charge to 100%, I would have thought would have a minimal difference on life expectancy. With lithium ion or polymer batteries, they do not age and degrade in the same way as a NiMH if you are constantly charging from 90-100%.

A statistical test on a generic lithium ion battery showed:-

For a full 100% discharge and full charge that the battery would last roughly 500 cycles, while one that has a 10% discharge and then charging back up to 100% would last roughly 4,700 cycles.

suniljp

As you mentioned with 2 pin power connector can also disconnect the battery from getting charged. It can disconnect the power source from the battery charging circuit when the battery reaches a particular % charge with the laptop running in AC power source. I do not think your laptop support adjusting the battery charging level to a customised %. Your laptop should have a particular hardware and the BIOS should support that. In some laptops the BIOS has the option to set battery charging level to a particular %. I have read somewhere that windows 8 do not support that feature, older version of windows (Vista) support that feature.

Some write up I found online might help you.

Memory Effect

First of all it's necessary to unfold a myth that persists in many peoples head.

The battery memory effect.

In lithium-based batteries this is in fact a myth, it only applies to older Nickle-based batteries. So fully discharging and charging the battery is completely useless and even harmful as we will see below.

The modern lithium battery can be charged regardless of its current percentage, given that it has absolutely no negative effect in its performance.

Should I remove the battery when A/C is plugged in?

Many laptop users have this question and we will answer it right now:

The answer is: YES and NO, it depends on the situation.

Having a battery fully charged and the laptop plugged in is not harmful, because as soon as the charge level reaches 100% the battery stops receiving charging energy and this energy is bypassed directly to the power supply system of the laptop.

However there's a disadvantage in keeping the battery in its socket when the laptop is plugged in, but only if it's currently suffering from excessive heating caused by the laptop hardware.

So:

- In a normal usage, if the laptop doesn't get too hot (CPU and Hard Disk around 40ºC to 50ºC) the battery should remain in the laptop socket;

- In an intensive usage which leads to a large amount of heat produced (i.e. Games, temperatures above 60ºC) the battery should be removed from the socket in order to prevent unwanted heating.

The heat, among the fact that it has 100% of charge, is the great enemy of the lithium battery and not the plug, as many might think so.

Battery discharges

Full battery discharges (until laptop power shutdown, 0%) should be avoided, because this stresses the battery a lot and can even damage it. It's recommended to perform partial discharges to capacity levels of 20~30% and frequent charges, instead of performing a full discharging followed by a full charging.

Laptop batteries contain a capacity gauge that allows us to know the exact amount of energy stored. However, due to the charging/discharging cycles, this sensor tends to be inaccurate overtime.

Some laptops include in their BIOS, tools to recalibrate this battery gauge, which is nothing more than a full discharge followed by a full charge.

So to calibrate the gauge, it should be performed, in every 30 discharge cycles, a full discharge non-stop , followed by a also, non-stop, full charge.

An inaccurate gauge can lead to the fact that the the battery capacity values are are wrong. The battery may report that it still has 10% of capacity when in fact it has a much lower value, and this causes the computer to shutdown unexpectedly.

Discharge (or charge) cycles consist of using all that battery charge (100%) but not necessarily all at once.

For example, you can use the laptop for some minutes in a day, using half its capacity e then fully charge it. If you did the same thing in the next day, it would be counted a discharge cycle and not two, so it may take several days until a full discharge cycle is completed.

rAfitiiixxx

Thank you guys for this responses Smiley Happy

1st of all, i've to say that my lenovo x220 doesn't need an special pin to do this, as i said, it's an special driver installed on windows xp that manages all this. At work i have a dock-station where i put my notebook (x220) and it ads a USB hub, more video and power supply exits and stuff, so i can use it as a desktop pc at my office. Then when it's connected with a special output (below the notebook, similar to an old video-game system catridge, lol) the notebook will charge but not use the battery unless AC adaptor gets unplugged. So yeah, it exists, and i don't know if it has a lithium battery or NiH, but i bet's lithium too. So this option is available in that model and my friend (the screenshot i posted early) has an ASUS laptop, and there's clearly a driver on Windows 8 that manages this power-supply feature wthout external drivers (since it's using the default battery tray icon and not some custom one like my lenovo with windows xp at work).

The feature exists, and i wanted to know if it does for this model too. Aparently it doesn't and i haven't found it. Still your full coment about lithium battery under heat is worse than having it plugged in all the time and also that these are prepared for small charges and discharges, i guess that it's not an exact solution to what i was looking for but it has been all i could have, so i will take it.

Thanks for your support! Smiley Happy

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