Buying battery from non-OEM manufacterers?

Where did you get what exact battery? The 2009 MBPs do not come with user replaceable batteries, thus I thought, only Apple would provide replacements, as the market for non-Apple battery replacements might be too low due to the procedure of replacing the battery.

Maybe the battery is just defunct?

There are lots of "junk" battery floating around. OK to hold u over until u get a new machine, otherwise...

I wouldn't trust or recommend any non-Apple battery, due to the number of problems reported with "knockoff" batteries. Also, there is no assurance that knockoff batteries have the same charging technology that Apple uses, involving the battery, the MagSafe adapter and the Mac's logic board.

Battery Replacement
Replacing the built-in battery in your MacBook Pro
Replacing the Battery in your MacBook Air
Intel-based Apple Portables: How to replace or service a built-in battery

The link below should answer most, if not all, of your battery/charging questions. If you haven't already done so, I highly recommend you take the time to read it.

Not sure about the 'NuPower' stuff from OWC, but I have NEVER heard someone say: "Wow, this cheap battery is Great.."

~ NEVER ~