The OnSite Defibrillator uses a disposable, lithium manganese dioxide, long-life battery with a five-year shelf life plus a (typical) four-year installed life. A spare battery should be stored with the defibrillator. Additional batteries should be purchased for defibrillators used frequently for training and/or demonstrations.
Type: 9 Volt DC, 4.2 Ah, composed of disposable long-life lithium manganese dioxide primary cells
Capacity: Minimum 200 shocks or 4 hours of operating time
Install-by date: Battery is labeled with an install-by date of at least 5 years from date of manufacture
Standby life: Typically, 4 years when battery is installed and when stored and maintained according to directions provided in this document

This battery fits both Philips OnSite and RFx AED models