The Iridium 9555 high capacity battery is designed to provide customers with up to 6.5 hours of talk time and up to 43 hours of standby time in full network coverage. Installation Instructions To install a new Iridium 9555 high-capacity battery as a replacement or spare, remove the current Iridium 9555 battery by lifting the top latch and pulling the battery forward. Install the new battery and charge for a minimum of three hours prior to use.