APC UPS Battery Replacement for APC Smart-UPS Model SMT1500, SMT1500C, SMT1500US, SUA1500, SUA1500US and select others (RBC7) - Newegg.com
Amazon.com: RBC7-UPC Replacement Battery for APC Smart-UPS SU1400, SUA1500, SUA750XL, SUA1000XL, SU1400NET, SU1000XLNET - Scroll Down for The Complete List of Compatible Models : Electronics
Continental Replacement Battery for APC SMART-UPS 1500VA USB and SER SUA1500 12V 18Ah NB UPS
APC Smart-UPS 1500 SUA1500 12V 18Ah UPS Battery - This Is an AJC Brand Replacement - Walmart.com