Warning: Battery cannot be identified, #5

Hi everyone,

I received this message upon startup:

"WARNING: The battery cannot be identified. This system will be unable to charge this battery."

This happened yesterday 8/13/2014. Some background information:

My laptop: DELL XPS Studio 1340

BIOS version/date: A15, 4/8/2011 (that's what my system information tells me)

Year purchased: 2009 (so the laptop is about 5 yrs old)

All the time since I purchased my laptop, I always have my battery in and AC adaptor plugged in (so, my understanding is that my laptop is using the A/C power from the wall). On Wednesday 8/13, I was using my computer for a little while. Then I turned off my computer. I turned back on shortly and this time the startup screen gave me the message. I hit the continue key. The desktop appeared and everything seemed OK, except that the power light is blinking (or flashing, I don't know the difference between blinking and flashing). I checked the batter meter on the task bar and it says battery fully charged 100%. So, I decided to remove the battery and solely use the A/C power plugged in and I can continue use my computer.

I'm confused and have several questions:

1) The computer says the battery cannot be detected yet the battery meter says fully charged 100%? So, is the battery dead or what?

2) Should I replace my battery? What's the lifespan of XPS Studio 1340 battery?

3) I checked the forum and found out that this problem has been reported by several users. Some suggested to replace the battery, others suggested to update the BIOS. So, I went to dell website and found the BOIS. The release date 4/13/2011 last updated 3/5/2014. So, I've the old BIOS? Should I update the BOIS?

4) I'm very apprehensive about updating BIOS. Will my computer settings, such as personalized desktop settings (screensaver, wallpapers, etc), my custom power settings, etc be changed to the default? Or what will change after updating the BIOS?

5) Right now, I've my battery removed and am using the A/C adaptor plugged in. My computer works fine. So, can I just don't use the battery at all and use the A/C adaptor to power my computer?

Any help would be very much appreciated. BTW, I'm a college student and running on tight budget.

Tom