Bought one of these batteries for a S4 last year - lasted half the time of the dead Samsung battery I was replacing it with - returned to takealot for a refund.
The other issue I had is the phone would say 15% left or 20% left - and would then just die... battery dead.
On that note about the battery dying much before it reaches 0%, imagine I only bought this battery 2 days ago but I'm already getting problems. The quality is incredibly weak, it needs a constant recharge.