APC by Schneider Electric Back-UPS Pro External Battery Pack (for 1500VA Back-UPS Pro models) - 24 V DC - Lead Acid - 4 Year Minimum Battery Life - 6 Year Maximum Battery Life - Office Supply Hut
Amazon.com: APC UPS 1500VA Sine Wave UPS Battery Backup, BR1500MS2 Backup Battery Power Supply, AVR, 10 Outlets, (2) USB Charger Ports : Electronics