So I downloaded Dell's Power Manager and I see it set to "Primarily AC Use." I now recall setting it that way soon after buying my laptop. But somehow it still is always at 100% and I now see in this article that the "Primarily AC Use," mode does not work on all devices. Seems like I have such a device.
Would I be accomplishing the same thing by putting it in ""Custom" mode and not having it go over 80%? When the laptop is in Primarily AC Use, does the battery constantly get charged until 80%, or does the power bypass the battery to power the device directly?
Was completely offline yesterday... So I'll try to address each of the above comments. (Full disclosure: I am not a PC repairman. My gemach is focused on purchases and component upgrades, primarily laptops. However, I do read about ten computer magazines as well as technology articles. My answers here are based on several articles about batteries and laptop power usage.)
Don't use a battery that has started to expand. Assuming your power cable plugs in well and is not in danger of being pulled out by a passing kid or the like, it is better to do that instead of using the computer with the battery inside - it stands to damage your components if it leaks (even without the possible fire hazard).
So far as a new battery is concerned, generic batteries lack the efficiency of the brand, but this usually translates into less time per charge and an earlier drop to dead than the original. I would think it depends on how often you use the entire charge (as opposed to the occasional two hours off the plug) and how much extra you would need to pay. Not sure where to buy replacements if you go generic, but buy somewhere with great customer service so you can get a replacement hassle free if you get a dud.
The battery doesn't expand because of overcharging unless something went wrong. You can totally use your laptop plugged in always - it is powered directly from the AC. Most laptops that I use have a setting to charge only to 80% enabled, which is a good idea if you rarely use the battery but helps only for how long the battery lasts before it dies completely (which is based on the number of charge cycles used). I let one of my laptops charge to 100% because I often need all of the battery power on that one. You save some stress on the battery by not doing this, but so far as that one is concerned, the tradeoff isn't worth it for me. It isn't the end of the world to let it charge completely.
As MG said, you can take the battery out - but only if you don't run the risk of suddenly losing power. If you would suddenly lose power, you may corrupt the data on your drives. You certainly would lose your work if you haven't saved it (or autosaved it).