Yosemite Battery

After upgrading to Yosemite my battery started acting up-- sometimes it charges, but most of the time it is drained which causes the computer to slow down and eventually shut down. Also the indicator light became unreliable, the battery might show 40% charge, but when I unplug magsafe it changes to 2%.

It is becoming increasingly harder to make the battery charge, I have to fiddle with the magsafe adapter (press on it etc). The battery makes scratching noise while charging and doesn't keep charge. MACBOOK AIR MID 2011

I have reset the battery a few time - no success.

Has anyone experienced these issues? Please help