Battery suddenly drains from 50% to 5%

So suddenly my battery goes from a little over 50% to around 5,6, 7 % and shuts down into sleep or hibernate (it is set @ 10% / 9% for low/critical battery action).

dv6763nr with battery 446507-0017F0814.
Notebook is about 2 years old-but battery check program results in a "Good" rating. EDIT...JUST RAN CHECK again THE PROPER WAY (When charging) and it says replace.

Before i buy a new battery maybe there is some other issue i need to resolve instead. Calibrated the battery today-went into sleep mode @ around 50%, battery then shows under 10% when awakened with a/c plugged in.
Charging seems a little bit faster- but no sudden jumps upward i think.

 

After a year or two, it's normal for batteries to lose their ability to hold charges. They decrease over time and become shorter and shorter...
I remember when I had the Inspriron 1520, I had 3 hours on it, after a year, it started getting weaker and weaker. After about 18-20months of owning the laptop, It started to have 45 minutes with very light usage, and about 20 minutes with wifi and brightness 50% on. Eventually all batteries be it your car, phone, laptop, whatever lose out and get weaker over time. Best way to keep it running is to keep the battery active. If the laptop is plugged in at a desk, at least once a week, take it off, let it run down the battery.

As for the car batteries, I had some crazy moments with them, won't get into it.