Whether yours is on the fritz or you just like to keep a spare tucked in your weekend bag, buying a low-quality battery can damage your phone or much worse. This Anker 2600mAh Li-ion battery has undergone rigorous quality control testing and is comprised of Grade A cells to ensure peak performance. Its built in IC-chip prevents overcharging, a major problem with inferior batteries. Good for almost all Samsung Galaxy S4 models, except the Galaxy S4 Active, this little guy can be scooped up for just $13.99 (Prime eligible). With the 5-star reviews, you won’t regret juicing up with this deal.