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I own an Acer Aspire 5755G on Windows 7 x64 and I recently read that keeping your battery charged at 100% the whole time degrades battery life.

The problem is, I always keep it in my laptop but never really use the Battery since the laptop (or should I say notebook) is rather big and I usually use it on my desk with the power cord. Although I remove the battery when gaming, I like to have it on most of the time as a UPS in case the power goes off.

Is there any utility that will keep the battery charged until, say, 20-60%?

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Sony provides a utility for this -- selectable from about 60 to 85%, IIRC. – Daniel R Hicks Aug 18 '13 at 18:36
up vote 1 down vote accepted

"I recently read that keeping your battery charged at 100% the whole time degrades battery life."

This is a myth.

It’s fine to leave your laptop plugged in at your desk when you’re using it, as the laptop won’t “overcharge” the battery — it will stop charging when it reaches capacity. However, just as you shouldn’t store your laptop’s battery at full capacity in a closet, you shouldn’t leave your laptop plugged in for months on end with the battery at full capacity. Allow your laptop’s battery to occasionally discharge somewhat before charging it back up — that will keep the electrons flowing and keep the battery from losing capacity.

Battery University says that “the worst situation is keeping a fully charged battery at elevated temperatures.” If your laptop produces a lot of heat, removing it might be a good idea. If you have a fairly cool laptop that you occasionally let discharge a reasonable amount, leaving it plugged in — even for days on end — shouldn’t be a problem. If your laptop gets extremely hot, you may want to remove the battery.

Read more at "Debunking Battery Life Myths for Mobile Phones, Tablets, and Laptops"

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A battery will last longer if only charged to 60-80% of capacity. This has nothing to do with "memory". This is why many manufacturers supply utilities that will limit charging to lower levels, if you do not need the long cordless runtime of a fully-charged battery. – Daniel R Hicks Aug 18 '13 at 18:36
I never mentioned memory. There is nothing wrong with leaving a battery charged at full power. – Keltari Aug 18 '13 at 18:52
Nothing wrong except it reduces battery life. – Daniel R Hicks Aug 19 '13 at 11:24

This is a topic of hot debate.

For lithium Ion batteries

You should drain the battery on a regular basis. I have seen many Apple laptops come into my computer repair store with dead batteries after just one year. In every case, it turns out the customer never exercized their battery.

Apple states in their documentation.

Apple does not recommend leaving your portable plugged in all the time. An ideal use would be a commuter who uses her notebook on the train, then plugs it in at the office to charge. This keeps the battery juices flowing. If on the other hand, you use a desktop computer at work, and save a notebook for infrequent travel, Apple recommends charging and discharging its battery at least once per month.

This also holds true for an Acer laptop using Lithium Ion batteries.

My general rule of thumb:

Lithium ion batteries last 3 years or 300 charges. Every month without a drain, shortens the batteries life by two.

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The circuitry built into the battery will not allow the battery to be overcharged. However, storing the battery at 100% capacity for long periods of time is bad for it. Completely discharging and recharging Lithium Ion batteries is also not good for them (this is ok for other types of batteries, such as deep cycled Nickel-Cadmium). Discharging Lithium Ion batteries below a certain voltage will ruin them (again, charging circuitry does now allow this to happen, but it is still bad to store them in this state for long periods of time, or even discharge them to 0%). The best way to store a Lithium Ion battery is to keep it between 40% and 60% charged. Some PCs support the functionality of maintaining the battery charge at a certain level (say 60%), as an option to improve battery longevity. If your PC does not support this, then discharging to about half capacity (50%) on a regular basis (perhaps once or twice a month) should be sufficient.

Another thing to consider is the price of replacing the battery (replacing a $100 battery in a $1000 laptop after 3 years of use is not terribly unreasonable, and many batteries are not even close to approaching that, unless you purchased a mac). If you always use the PC plugged into the wall, is it really necessary to replace the battery when it goes bad?

I used to work for a lab that researched Lithium Ion battery technologies, so I might tend to be a little more familiar with Lithium Ion batteries than most people...

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