Hybrid car battery cost depends on the vehicle manufacturer and the warranty that they establish. For example, you cannot simply replace one battery of a Honda's hybrid IMA system, you must replace them all. Because of the numbers of batteries involved in each rack, you would have to disconnect each battery from the series chain and test it, so it is easier to replace the whole set. Honda has a 6-year/80,000 mile battery replacement warranty, while Toyota's policy is 8 years and 150,000 miles. In either case, you are looking at a $3,000 bill for a Honda Hybrid battery replacement, and about a $3,500 bill for a Toyota battery replacement. If, on the other hand, you are lucky and are just replacing the standard engine battery that feeds the engine (there's only one of them), you are probably looking at a $115 bill with labor.