APC SMART-UPS 750 SUA750I Battery Replacement - UB1280 Universal Sealed Lead Acid Battery (12V, 8Ah, 8000mAh, F1 Terminal, AGM, SLA) - Includes TWO F1 to F2 Terminal Adapters - Walmart.com
MIGHTY MAX BATTERY 12-Volt 8 Ah Replacement for APC Back-UPS ES 750 UPS Battery ML8-121152 - The Home Depot
Refurbished: APC Back-UPS BE750G UPS (Back Up Power Supply) - Newegg.com