Today’s Question: My laptop is always plugged in to power, but I am wondering if that is causing damage to the battery? I have heard conflicting advice on this – some say it is best to allow the battery to drain down to 20 or 30% then recharge, others say you can leave it plugged in all the time. And is it best to turn the computer off every day – or is it okay to always have it on (but sleeping)?
Tim’s Quick Answer: In general, I recommend allowing a laptop battery to partially discharge once every week or two. I also recommend restarting the computer every couple of weeks, though shutting it down completely is not necessary.
More Detail: Allowing a battery to periodically discharge can help ensure the battery is able to hold a higher level of charge over a longer period of time. I therefore recommend allowing batteries to discharge to a moderately low level at least periodically.
It is understandable that this topic can be a bit confusing. First off, for today’s lithium-based batteries this issue of batteries losing some of their power if they aren’t discharged periodically is not anywhere near as significant an issue as it used to be for older battery technologies such as nickel metal hydride batteries. It is still an issue, however.
Batteries do have a somewhat limited number of charge/discharge cycles before the effectively wear out. However, this is not likely to be a significant issue for most users, as the battery would likely be replaced before this were to become a problem.
The more likely issue is a decrease in total battery capacity if it is not discharged periodically. This is an issue I have faced myself over the years, since I use my laptop primarily as a desktop replacement, and therefore tend to keep it plugged in much more than I should. My wife, on the other hand, almost always works with her laptop not plugged in to power. Over time my laptop battery has the top power level diminished considerably more than my wife’s laptop.
If you make sure to let the laptop battery discharge to a relatively low level (around 20%) every couple of weeks, you’ll help ensure the battery is able to hold a higher level of charge.
Shutting down the computer isn’t necessary, though it can be helpful to restart periodically just to clear out memory that wasn’t released, clear caches, and otherwise give the computer a bit of a reset. I recommend restarting at least every couple of weeks, or more often if the computer doesn’t seem to be performing normally.