Rechargeable batteries, which can be used again and again through top-ups from the mains-connected charger, are an investment – the best will last for hundreds of hours of use. They have several ...

(Note that the batteries aren't rechargeable ... Battery life was 7.3 hours for an Energizer, 6.8 hours for a Duracell, and 4 hours for a Toys "R" Us battery.