Will the OSI Alarm System still work on Back-up battery during the power failure?

Yes the Alarm System will still function normally. Sensors can still be triggered, wirless Siren (optional accessory) will still work, you can still make changes to the control panel, and you will still get notifications.

Note: please remember to switch the back-up battery from off to on when you first plug in the alarm system, this is defaulted to the off position when you first purchase this product.