power banks

Power Banks are devices using to charge cell phones and other electronic gadgets they are portable.Powerbanks are rated in mAh (milliamp hours), just like the battery in your cellphone. They have about 70% to 80% efficiency; the rest of the energy is lost to heat. This means, for instance, that a 3600 mAh powerbank wouldn’t completely fill your S4’s 3600 mAh battery. Even a 4000 mAh unit would fall a bit short (do the multiplications – even 0.80 x 4000 is less than 3600). On the other hand, you’ll probably hook up the powerbank before your battery is completely dead