[Q] Is it harmful for battery to use the laptop on AC power when the battery are in and fully charged?

Is it harmful for battery to use the laptop on AC power when the battery are in and fully charged...?

 

It shouldn't make an appreciable difference, my M17x R2 9 cell battery is plugged in all the time for almost 1 year now, and the battery has been fine.

 

thanks Tsunade_Hime is there any over charging issues? or this is only a myth!

 

The new batteries are not affected by this old laptops dating 2005 and bellow had their batteries life depleted by keeping them plugged in that is no longer the cause unless your laptop is basically ancient.

 

Li-ON batteries shouldn't have the memory issues of older nickel batteries. If you planning on not using the batteries for an extended period or if you have spare ones, I think you are supposed to let them go to 30-40% and store them in a dry cool area.

 

The batteries will be fine. If AC power is constant and not intermittent, the battery will first charge to 100% capacity, then stop charging and slowly lose charge by itself. Your computer will still say 100% charged, but if you unplug it you can see it drop down to the actual percentage of charge remaining. Also, it discharges very slowly. You will need days left plugged in to see a difference. But this difference means that keeping the laptop plugged in has no adverse effect on the battery.

 

one year is too small a sample imo.

 

The main issue that may affect your battery longevity is not so much the constant charging but heat. If your laptop chassis tends to heat up a lot with a lot of conduction to the battery then it may be beneficial to remove the battery pack as Lithium Ion hates heat. Otherwise, it isn't an issue.

 

Basically, it isn't harmful. Technically, your battery's lifespan won't be quite as long. But the difference is unlikely to be appreciable. For 99% of it, it makes more sense to keep the battery in all the time so that if you spontaneously lose power to due a power outage, the dog tripping over the cord, etc., you don't lose your work. You might reach an annoyingly low battery life a few weeks sooner, but it'll probably save you often enough to be worth it. It might be different if your power cord is usually connected to a UPS, but I doubt most laptop users do that.

In my experience, leaving the battery plugged in almost all the time, my first battery lasted 3.5 years, and the current one is up to two and change so far. YMMV depending on manufacturer, initial capacity, etc. I suspect actual battery cycles is a considerably larger factor than being plugged in while charged.

 

We need to make a battery sticky thread. In any case my opinion is to leave it plugged in. Period. Batteries lose charge for several reasons:

(1) Too high heat. Usually leaving it in a hot car for a day is more problematic than being slightly warmer in the laptop while gaming and leaving it plugged in for months on end.
(2) Using your laptop on battery. But that's what it's designed for. They say roughly 500 discharges before your battery will provide 50% original capacity. But that's why we have laptops, for portability, right?
(3) Time. Leave it plugged in or take it out, if not used in either case it will lose peak capacity. It's the nature of the battery. There are ways to prolong its life, as noted 40% and store in a cool temperature, but it's maybe adding an extra few months of life.

The battery acts as a built-in UPS. I'd much rather leave it in, in case you accidentally yank out the power cord, power goes out, any number of reasons. People pay hundreds of dollars for UPS for their desktops yet people are stingy with a $50-60 battery that comes standard with their laptop.

IMHO, the risk of losing data and damaging components due to an unexpected shutdown far outweigh the extra few months you might gain from being meticulous about storing it. Leave it plugged in. My $0.02.

 

My 3 year old Vaio and my new Lenovo both have a "Battery Maintenance" option. The Vaio offers a 50% and 80% setting, essentially keeping the battery from fully/over charging. The Lenovo has the option to fully configure the charging levels. The Vaio still reports very good health and, while it never had great battery life, it is nearly the same as when it was new.

I almost always have the laptop plugged in and this kind of option gives me additional reassurance that using mainly ac power does no harm at all.

 

It is a nice feature to have the 80% option, as I've seen many laptops have it. However, keep in mind that whether at 80% or 100%, once it breaks below the "threshhold" %, maybe 99% for fully charged or 79% for 80% setting, it will still charge it until it reaches that capacity. In either case it can take a week for it to drop down 1% so it's not like it's keeping a constant charge on the battery. It's only on occasion when it drops below the "must recharge threshhold" or if you use it on battery and plug it back in.