Amazon.com: UPG 12V 8Ah Battery Replacement for APC Back-UPS 500 Battery - 2 Pack : Health & Household
Amazon.com: Replacement for APC Back-UPS CS 500 BK500 Battery - Replacement UB1290 Universal Sealed Lead Acid Battery (12V, 9Ah, 9000mAh, F1 Terminal, AGM, SLA) - Includes Two F1 to F2 Terminal Adapters
Amazon.com: AJC APC Back-UPS ES500 ES 500 VA 8 Outlet BE500R 12V 7Ah UPS Battery - This is an Brand Replacement : Electronics