In the beginning top, now very weak

Have this battery bought 2 years ago and was very happy at the beginning, it was even able to keep up with the original battery.
But after about a year (and I photograph really just on vacation, so I would say, after 1-1.5 months in total), it has become much weaker.
I do not know why.
I always have a feeling that even when loading something goes wrong, because the battery is being charged much more quickly than the original battery. Maybe it is not properly recognized by the charger and under charged ... But in the beginning, when it was still new, it had indeed somehow works ...
In any case, you can take the battery for one year, and it's getting worse, just maybe do so at the 50 photos or even less. In addition, my camera is not a flashing red icon with him, but it's just from one moment to the next blank. Already more than once thought that my camera died ...
So now it is no longer brauchtbar.