My laptop makes a very loud noise (coming from some CPU idles state / power saving mode). This is a well recognized problem, and people on the internet seem to have not found a solution yet.

The problem occurs when my battery is fully charged (and computer switches to only using power from the AC adapter).

  • Is there some way to limit the charging proces to 95% (hence preventing the noise to start at 100%)?
  • Is it healthy to let the battery fully charge (daily) and then put out the cable, and recharge the battery when it is almost empty? I don't khow this will impact my battery, in contrast to using mroe AC adapter at 100%.

thanks in advance

  • It probably won't solve your problem. When the laptop stops charging it starts running on AC power, no matter if it's at 100% or 95%.
    – gronostaj
    Jan 23, 2015 at 11:13
  • My Dell has a tool which limits the charge level to 75%. Which laptop do you use? Jan 23, 2015 at 16:33

1 Answer 1


To answer your first question:

Commercial chargers do not allow changing the charge voltage limit. Adding this feature would have advantages, especially for laptops as a means to prolong battery life. When running on extended AC mode, the user could select the “long life” mode and the battery would charge to 4.00V/cell for a standby capacity of about 70 percent. Before traveling, the user would apply the “full charge mode” to bring the charge to 100%. Some laptop manufacturers may offer this feature but often only computer geeks discover them.

Generally speaking, modern Li-ion batteries suffer very little from degredation.

the worst situation is keeping a fully charged battery at elevated temperatures. This is the case when running a laptop off the power grid. Under these conditions, a battery will typically last for about two years, whether cycled or not. The pack does not die suddenly but will give lower runtimes with aging.

However, the best way to keep your battery healthy is to completely unplug the battery when you're running on AC power for extended periods (i.e. a full week or more on AC power) and store the battery with about 50% charge.

“Should I disconnect my laptop from the power grid when not in use?” many ask. Under normal circumstances this should not be necessary because once the lithium-ion battery is full the charger discontinues charge and only engages when the battery voltage drops. Most users do not remove the AC power and I like to believe that this practice is safe.

Also worth noting, with regard to the second part of your question, is that Li-ion batteries are kept most healthy by being charged when they reach about 20-40% capacity.


For further reading please refer to this article from batteryuniversity.com, which is also the source for the quoted parts of this answer.

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