Battery level, unfortunately, never higher than 80%

I bought this battery because of the many good reviews and the price.
Unfortunately, not everything was fine with it and I had to return him after I had the laptop including the new battery connected when switched off the charger and charged overnight, me only a battery level of 79% was the next day when you turn displayed. Even after I have the laptop repeatedly fully developed and then fully charged again, nothing has changed except for an increase to 80%. Strange was that from these 79% and 80% the power supply has not loaded and it therefore seemed as though the battery is fully charged. I was able to also work more hours without having to connect the device.
To rule out that this error is due to my laptop or the adapter, I have installed my old original Samsung battery again and this completely fully charged. In this case, however, my full 100% were reported.
In the hope that this issue is just exactly this, I sent articles, I have now returned it, and will order me exactly this model again. Should that be any better, I'll revise my review again.
Otherwise was both with the delivery, as well as the battery itself all right and to my satisfaction!