This product 3200mAh ad, so in view of the original battery that is 2100mAh, it is expected easily double the life of the battery, but in fact it is not. Since this battery recharges the internal battery (like a charger), there is a lot of energy losses in heated, can earn between + 50% and + 80% of battery life, which is already good, but a little surprising when one reads 3200mAh ... I no longer use this product in the end, which generally weighs down my phone, and improves her that too little autonomy. I prefer to use a replacement battery that I needed to load, and I change battery. My phone is lighter and ultimately it is cheaper.
On the plus side, it's nice to see the battery level remaining in the reserve, and be able to plug directly above a charger without having to disassemble it.
This is not a bad product, but it is not effective enough for my taste, it is better to buy a spare battery.