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Assuming an external 24V power supply, an SDC configured with two Openpath Avigilon Readers and locking hardware uses about 1.1 Amps. To keep the system running for 3 hours with all entries engaged, you need 1.1A x 3 hours = 3.3 AH, so two 12V 4AH sealed lead acid (SLA) or gel cell batteries in series.
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