A friend replaced her laptop's battery after only two years because it wouldn't hold a charge. I suggested she shouldn't keep her laptop always plugged in, but I wondered—was this outdated geek lore, rendered obsolete by modern batteries?
Photo by candescent.
Yes and no. It depends, of course, on what kind of battery you have. Battery technology has come a long way over the years, and surely in 2009 you don't have to worry about how long your laptop's been plugged in. However, one major notebook manufacturer (which ships Lithium-ion batteries) thinks you should, and suggests adding a reminder to your calendar to deplete and recharge your battery once a month. To quote: "Apple does not recommend leaving your portable plugged in all the time."
My friend, however, has a two-year-old Dell. Cursory Googling for her model didn't turn up the equivalent of Apple's definitive statement, only lots of opinions which ranged from "it's a non-issue" to "yes, it kills batteries!" Dell.com's battery recommendations page doesn't say anything about not keeping your notebook plugged in. HP's battery tips page doesn't answer the question, either. I pored through my wife's ASUS Eee PC user guide and didn't find any warning about continuous charging. A non-mention might make you think it's a non-problem, but if this is an issue for Apple notebook batteries, it is for PC notebooks with lithium-based batteries too. When I asked, my Twitter followers returned mixed replies, but many notebook users (both Mac and PC) DID report anecdotal battery problems when the machine was plugged in constantly.
Other folks more educated about the differences in battery types than I am dropped knowledge about which ones are problematic and which aren't. Learn from all the respondents' suggestions, research and hard-learned lessons at the full post.
Unplug Your Laptop Regularly (When In Doubt) [Smarterware]