This calculator is a guide to determining the required back up battery capacity of your system. 

Total DC load is the total Current drawn by the equipment installed based on 24V DC supply.

Back up duration for full load consumption is based on average duty cycle of the audio ( typically 20% for speech ) and the duration required is based on the Consultants' / Authority requirement, typically 0.5 to 1 hr. Standby duration is normally 1 to 3 hours.

Residual voltage of batteries shall be for this calculator is 70% to ensure proper operation of the overall system.

Battery bank capacity shown is the nearest value of standard battery Ah available, normally in 26, 40, 60 and 100 Ah, installed as 2 x 12V block


This is an example for connecting back up supply for small loads, typically less than 25A at 24V DC.

The power packs linked in series to form 24V, shall be terminated at BC9740 Battery Charger's BATT IN terminals and thereafter to PS9400 Power Supply's Batt connectors.


Ensure that the appropriate size of connecting cables are used to suit the total loading. In this setup, we recommend 2.5mm with high temperature PVC insulation cables.

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Last updated on  26 DEC 2019
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