First time answering something on this forum!
Disclaimer - I do not own a Toshiba Satellite.
It sounds like the battery indicator in your battery is faulty. However, superuser.com had a similar posting and the following solution seemed to help one person out. Try it out, but otherwise, I think you may have to replace the battery. How long have you had the machine? Also, it helps if you add things like screenshots and more info like whether you've installed new hardware or battery related software recently.
"You can try and remove the battery and turn the laptop on using the AC/DC adapter only. Then turn the laptop off, re-insert the battery and turn the laptop back on using battery power only and no charger plugged in. This may reset the system automatically so the laptop will read the correct amount of battery charge. Then fully charge the battery with charger. Once fully charged, remove the charger and let the battery drain on its own. Fully charge the battery and now see if it got right!"