Hybrids are becoming a mainstream, there are many hybrid models offered, and they are more popular than ever. So the question of battery life in a hybrid is only too relevant.  As people search for used hybrid, or an original owners hybrid gets on in years they must face this question.  We know that no battery lasts forever, even advanced rechargeables like those in hybrid cars.  The reason is that after a certain amount of electrons moving in and out of its cells, a battery loses its ability to hold enough charge and is no longer able to perform the way it should.  There is no specific answer for the hybrid battery question.  Toyota claims that its hybrid battery (“traction battery”) is designed to last “the life of the car.” But this has come to be known as a controversial statement.  For Toyota, the life of the Prius is defined as 180,000 miles, and the nickel-metal hydride (NiMH) battery is expected to be effective that long. To verify the claim, they offer an superb battery warranty: 100,000 miles or eight years, in 42 states. In the eight other states that have adopted higher standards, it is 150,000 miles or 10 years.  Other hybrid manufacturers have followed suit with their own warranties on the battery.  Because Hybrids are so relatively new, the oldest ones just reaching ten year, this question will only be answered in the coming years.  A study showed the failure rate for Prius batteries made in their first year of production with a failure rate of only 1%, and the second year Prius’ have a battery failure rate of much less then this.  This is good news, and for Hybrid owners, between the warranties offered and the studies on the older models, a breath of confidence in their vehicle.