Rechargeable battery for Heartstart FR2. The battery will take no longer than 3 hours to fully charge. It should be fully charged before putting it into use. Installation procedure: - Charge the Philips HeartStart FR2+ Rechargeable Battery Pack as per the instructions that came with the battery and the charger. - Squeeze the yellow latch on the old battery pack to release and remove it from the AED. - Make sure there are no electrode pads connected to the AED. - Hold the freshly charged Battery Pack by the yellow latch and carefully slide it into the battery cavity at the top of the AED. - Slide the Philips Rechargeable Battery Pack into the AED until you feel and hear it click into place. - Watch for your AED to commence a self test that takes approximately 90 seconds to complete. In order for your Philips HeartStart FR2+ to recognize the rechargeable battery and its present capacity, it is essential to let the battery insertion self test complete.