NICKEL- CADMIUM BATTERIES
Old cellphone batteries were big and bulky, forcing many early-version mobile devices to take on their colloquial brick-like shape. Nicad batteries are rechargeable, which was a revelation in the early 1990s, but they suffered from memory effect, which reduced their usefulness over time with every subsequent charge and discharge. It’s from these batteries that the urban myth of having to charge your smartphone up to 100% and then only recharge it again once it gets down to 0% continues to propagate. Modern lithium-ion polymer batteries do not suffer from memory effect, and actually enjoy a prolonged life span if they are charged in short spurts between 20% and 80%, never being allowed to reach full- or zero capacity.