Triad UPS600 replacement battery pack (rechargeable, high rate)
Triad UPS600 UPS Set of 2 Replacement Batteries
APC BACK-UPS 600 BN600 Battery Replacement - UB1290 Universal Sealed Lead Acid Battery (12V, 9Ah, 9000mAh, F1 Terminal, AGM, SLA) - Includes TWO F1 to F2 Terminal Adapters - Walmart.com
Universal - APC Back-UPS 600 UPS Battery
RefurbUPS Back-UPS 600 (BN600) High Capacity 9 Amp - Compatible Replacement Battery Kit For RefurbUPS APC Compatible - Newegg.com