Is my battery on it's way out.....

[Major Rant]

If the second reading is signifcantly lower than the first then the battery is shorting out internally.

Not true my friend ...  :\

If you charge a good battery to , say, 13.5V and then take it off charge it will still read about 13.5V. Over the next few hours it will decay exponentially to  well below 13V.