MB won't stay on when unplugged from power adapter

A few months ago my computer would not start up from a fully charged battery. It would start up and stay running if it was plugged into the adapter. I let it get a good few days charge on the adapter and had success with being able to use my battery to power my laptop. This week I tried using it on battery power at school and it worked fine for a few hours. I knew I wanted to conserve battery power that day so any time I left it I made sure to put it to sleep to conserve battery power, since I had not brought my power adapter with me. When I went to use it later that day it would not awake and made the same sound it had made for me a few months ago. I don't get a response when I hit the space bar to awake it so I hit the power button again. It then sounds like it is starts but immediately shuts off. I brought it home and plugged it in to the power adapter and it works fine on it but when I remove the power adapter it immediately shut down. I checked the battery status and all looks good there. It is as if when it is disconnected it thinks there is no battery power. Any ideas out there! It is frustrating having a laptop that can't be untethered.

System Power Settings:

AC Power:
System Sleep Timer (Minutes): 0
Disk Sleep Timer (Minutes): 10
Display Sleep Timer (Minutes): 10
Automatic Restart On Power Loss: No
Wake On AC Change: No
Wake On Clamshell Open: Yes
Wake On LAN: Yes
Display Sleep Uses Dim: Yes
Battery Power:
System Sleep Timer (Minutes): 15
Disk Sleep Timer (Minutes): 10
Display Sleep Timer (Minutes): 5
Wake On AC Change: No
Wake On Clamshell Open: Yes
Display Sleep Uses Dim: Yes
Reduce Brightness: Yes

Battery Information:

Battery Installed: Yes
First low level warning: No
Full Charge Capacity (mAh): 4551
Remaining Capacity (mAh): 4551
Amperage (mA): 0
Voltage (mV): 12543
Cycle Count: 175

AC Charger Information:

Connected: Yes
Charging: No

Hardware Configuration:

UPS Installed: No