We bought a Lenovo B450 laptop almost a year ago. It comes with a NVIDIA GEFORCE with CUDA graphics and so the battery life is terrible. It will only last 1:30 hours max.

We try to run it on battery as much as possible but because the battery life is short sometimes we can't notice that the battery is so low until the computer blacks out.

Because of the short battery life, the laptop is always plugged on AC power. One night the computer froze. Because it was already late, I just reset the laptop my pressing the power button for 10 seconds. The laptop shut off but I did not bother restarting it.

The next morning, the laptop won't turn on on battery only. It will only turn on on AC power. The computer instantly shuts down(improperly) once the adapter is removed. But the battery was at 100% then. Now it is slowly losing charge (currently at 74%). The battery indicator says, "Plugged in, not charging".

I want to bring the laptop to school but I can't because it won't be portable at all.

Just to summarize it all:

1) The laptop suffered some blackouts already.
2) The laptop was on AC power most of the time.
3) When the computer froze, it was reset (hard shutdown).
4) The laptop won't boot with battery only since then.
5) The laptop will shutdown instantly when AC adapter is removed.
6) The battery won't charge and is gradually losing charge.

======================= UPDATE =============================

We got the battery replaced. Unfortunately, it delivers only 2 hours max of power.