Problems with dell xps 1330 laptop battery. Battery show 4 lights, but when computer unplugged

[RC]

7. Question - Is the laptop run on the charger most of the time?

Your problem sounds like the laptop battery problems we had at work, before I retired. The laptops sat in the docking station most of the time. The battery was seldom actually used.
What would happen, the battery would be charged up when first put in the docking station, the system would check the battery once, after that the battery would self-discharge, because the system never checked it again.
That is hard on Lithium-ion batteries.
The solution was to remove the laptop from the docking station and run it on the battery a couple of time a month, then but it back. The system would then check the battery and recharge it.