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
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.
- 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
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
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.
(or charge) cycles consist of using all
that battery charge (100%) but not necessarily all
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.
How to perform a calibration (full discharge)?
The most adequate method to do a full discharge
(100% to a minimum of 3%) consists of the following procedure:
- Fully charge the battery
to its maximum capacity (100%);
- Let the battery "rest"
fully charged for 2 hours or more in order
to cool down from the charging process. You may use
the computer normally within this period;
Unplug the power cord
and set the computer to hibernate
automatically at 5% as described by the image sequence
below (click images to enlarge). If you
cannot select 5%, then you should use the
minimum value allowed, but never below 5%;
- Leave the computer discharging,
non-stop, until it hibernates itself. You may
use the computer normally within this period;
- When the computer shuts
down completely, let it stay in the hibernation
state for 5 hours or even more;
- Plug the computer to
the A/C power to perform a full charge
non-stop until its maximum capacity (100%).
You may use the computer normally within
After the calibration
process, the reported wear level
is usually higher than before. This is
natural, since it now reports the true current
capacity that the battery has to hold charge.
Lithium Ion batteries have a limit amount of
discharge cycles (generally 200 to 300 cycles)
and they will retain less capacity over time.
Many people tend to think "If
calibrating gives higher wear level, then it's a
bad thing". This is wrong, because like said,
the calibration is meant to have your battery
report the true capacity it can hold, and it's
meant to avoid surprises like, for example,
being in the middle of a presentation and
suddenly the computer shuts down at 30% of
To store a battery for long periods of time,
its charge capacity should be around 40% and it
should be stored in a place as fresh and dry as
possible. A fridge can be used (0ºC - 10ºC),
but only if the battery stays isolated from any
One must say again that the battery's worst enemy
is the heat, so leaving the laptop in the car in
a hot summer day is half way to kill the battery.
Purchasing a replacement battery
If you intend to purchase another battery, it's
recommended that you do it only when the current
battery is very degraded. If it's not the case,
the non usage of a battery leads to its degradation.
If a spare battery is purchased and won't be used
for a long time, the above storage method should
Besides that, when purchasing a battery you must
pay attention to the manufacturing date.
Advantages in using BatteryCare
BatteryCare allows you to have the control over
the discharge cycles number, and when this reaches
30 (or other configured value), it notifies you
that it's time to perform a full discharge in order
to keep the battery gauge calibrated.
Like this, it's guaranteed to always have the correct
capacity values reported by the battery.
Besides, when using the battery, there's the
possibility to suspend some Operating System features
that help degrading the autonomy (only in Windows
Vista or higher):
- Windows Aero,
the theme that allows for visual effects like window
transparency, requires graphics card acceleration,
which obviously will help decreasing the battery
ReadyBoost and SearchIndexer
are three Windows Vista (and higher) services that,
even in battery mode, are using the hard disk a
lot and increase total power consumption, thus decreasing
battery lifetime. Suspending these services has
absolutely no negative impact on the performance
or security of the system.
These features are resumed once the laptop is
plugged in to A/C power.
Table with information about
other types of batteries