Battery with reverse polarity?

Hello, my 4th-gen iPod touch battery had died, and i bought a new one on Ebay .

The problem is that the polarity is reversed.

My original battery says " - + " whereas the new one says "+ -" ...This dawned on me after installation.

When i reassembled, everything booted and started charging.

Only thing is the battery does not have any more life to it than my old one.

Is this a failure to charge due to the polarity, or is it just a cheap junk battery ?

Also my iPod says revB on the board, I don't know if this helps.

Thx in advance...