Amazon.com: ExpertPower 6 Volt 4.5 Amp Rechargeable Battery (4 Pack) : Health & Household
Power Kingdom 6V 4.5Ah PS4.5-6 6 Volts 4.5 Ampere Rechargeable Sealed Lead Acid Battery - Arnaiz Electronics and Electrical Supply
Mighty Max Battery 6V 4.5AH SLA Multipurpose Rechargeable Battery Rechargeable Sealed Lead Acid 645 Backup Power Batteries in the Device Replacement Batteries department at Lowes.com