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CrazeD 05-27-2008 12:45 AM

Does using AC harm the battery?
I've heard that using AC power while having the battery plugged in for extended use will damage the battery and shorten battery life.

Is this true?

I'm getting my new laptop in hopefully 2 weeks or so, if all goes well, and it will be used a lot with AC power...don't wanna ruin the battery.

Luke 05-27-2008 01:55 AM

Re: Does using AC harm the battery?
yes, using the ac with the battery in can harm the battery very quickly.. 2 or three uses of like 2 hours can permanently shorten the battery's charge hold and life span. Always have the battery out when the ac is plugged in. Never use the laptop when its charging. Have the laptop off when it is charging. Keep the battery out of the laptop when not in use.

CrazeD 05-27-2008 06:13 AM

Re: Does using AC harm the battery?
So it wasn't a myth. :)

Thanks for the info.

KurrentEweser 05-27-2008 07:03 AM

Re: Does using AC harm the battery?
I've left all my laptops plugged 24/7 for years and never had any problems.

Laptop battery tips

CalcProgrammer1 05-27-2008 01:12 PM

Re: Does using AC harm the battery?
I'm pretty sure that IS a myth...I leave my laptops (2 of them) plugged in nearly 24/7, only use battery when I take the PC out to the kitchen while I'm eating or if I use it on a trip or something. Most of the time it's on my desk, plugged in, and powered up (running folding@home).

Maybe on older (NiCd or NiMH) battery types this was the case. Nickel Cadmium (NiCd) and Nickel Metal Hydride (NiMH) batteries suffer from capacity loss if they are recharged before they fully deplete their charge. If you unplugged your NiCd or NiMH laptop and used it for like 5 minutes and then plugged it back in, this could damage the battery.

Modern laptops, however, use Lithium Ion batteries (Li-Ion). These batteries don't suffer from the "memory effect" that NiCd and NiMH batteries did. You can unplug a Li-Ion laptop and run it for a few minutes and plug it back in, the battery will charge back to 100%, and the battery won't be damaged.

Also realize that most of the time your laptop is plugged in, the battery is not charging. The laptop charges the battery to 100% and then stops charging it. Most of the time, the battery is just sitting there, just as it would if the laptop were turned off and unplugged. Therefore, the only thing that could possibly hurt the battery if you leave your laptop plugged in and turned on is the CPU/GPU heat, and if you keep your laptop cool (use a cooling pad or something if you do intense processing on it), the battery won't even get warm.

Luke 05-27-2008 04:43 PM

Re: Does using AC harm the battery?
i know first hand with laptops guys, my work gets them in all the time, newer laptops that batteries don't last nearly as long as they should. So follow what i said in my first post.

^ and calc, did you ever use your laptop using the battery properly...becuase if you haven't then you would not be able to tell how long the battery should last.

CalcProgrammer1 05-27-2008 05:37 PM

Re: Does using AC harm the battery?
I do know that laptops shut off the charging system after the battery reaches 100% charge. How is that any different from turning your laptop off and not plugging it in? If a battery is left on a charger 24/7 (a charger that doesn't shut off after the battery reaches full charge), then yes, the battery will suffer significant capacity loss, but modern chargers (such as those in laptops) monitor the charging process carefully.

Also, having the laptop off when charging? What on earth is the point of that? Charging a battery is usually a low-power process. Unless a battery charger is rapidly charging a battery, it is charging with less power than it will put out. As long as your laptop's power supply isn't too low, it should be perfectly capable of both running the PC and charging the battery at the same time. It would be stupid for a manufacturer not to provide an AC adapter that couldn't do both at the same time, as you plug your laptop in when your battery starts to die so that you can continue working or using your computer.

Again, keeping the battery out of the laptop when not in use...The laptop already does this. Charging current is stopped on most laptops after the battery reaches 100%, so the battery is essentially disconnected. The only thing connected is the monitoring system, which makes sure the battery stays at 100%. Should the power drop lower, the charger may slowly feed it power to bring it back to 100%.

Luke 05-27-2008 05:52 PM

Re: Does using AC harm the battery?
arggg, ok. When the battery is left in the laptop when the ac is in the laptop will draw a bit from the battery and most from the ac...but as you draw a bit the laptop starts to charge the battery. IT continues this process. So if you had the laptop off when charging there would be nothing being drawn except for the tiny bit that leaks..thats why if you wont be using the laptop for a while the battery should be out of the laptop.

Please, untill you have seen first hand what this does to a laptop stop filling he's head with things you think are right :).

Put it this way, why would the battery me so easilby removable if you would only have to take it out to replace it...the companies that make the laptops don't tell you how to properly treat the battery for you damage it and buy another one from them eventually.

KurrentEweser 05-27-2008 06:32 PM

Re: Does using AC harm the battery?
Lithium Ion batteries have built-in circuitry that controls and monitor its charge and discharge. The laptop just supplies a stable source of current for this circuitry to do it's job. Batteries will go bad as they age whether the laptop is left plugged in or not. Remember you get what you pay for. Buying cheap generic batteries are a crapshoot. You might get one that only lasts a few charge cycles.

Follow these tips to prolong your batteries life. Laptop battery tips

Ste 05-27-2008 06:37 PM

Re: Does using AC harm the battery?
I use my laptop all the time while it is charging, and I can say with certainty that the battery does not last as long as it used to.

When I first bought it, I could get maybe 2 hours and 20 minutes out of a full charge, now after a year and half, I am lucky to get an hour and 30 minutes.

very lucky.

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