Philips brand AEDs operate on batteries only. Always have a fully charged spare.This Philips Lithium Battery Pack is the aviation lithium manganese dioxide battery for your Philips HeartStart FR3 AED. This battery pack has a shelf-life of 5 years from the date of manufacture so having an extras on hand is always a good idea. This Philips aviation battery pack will last up to 3 years in your FR3. According to performance data from Philips, a new FR3 Battery Pack should provide up to 300 shocks or 12 hours of patient monitoring capability. Philips HeartStart FR3 Aviation Battery