Battery kit for APC Back UPS ES 500 replaces APC RBC30
Amazon.com: APC Back-UPS CS 500 12V 8Ah UPS Battery - This is an AJC Brand Replacement : Electronics
APC Back-UPS CS 500 BK500 Battery - Replacement UB1280 Universal Sealed Lead Acid Battery (12V, 8Ah, 8000mAh, F1 Terminal, AGM, SLA) - Includes Two F1 to F2 Terminal Adapters : Amazon.ca: Health