A small battery pack can be added to the ACM5000 and ACM5500 model to power it in the event of a power failure. To do this you will need to use a battery pack and an appropriate battery charger in lieu of the Opengear supplied 12V DC power adapter.
The ACM’s can operate between +9V to 30V DC, so the battery pack and charger need to be within this range. Opengear recommends using a 12V DC battery pack. The battery charger should provide the proper charge voltage and characteristics for the type of battery pack you use, Li-ion etc. as well as supply sufficient current to be able to charge the battery and power the ACM unit at the same time. We recommend a 1A charger as a minimum. The Li-ion battery pack also should be equipped with overcharge, over discharge and current limiting circuitry for battery protection.
Depending on the type of battery pack you source you will need to make the proper power connections between the charger, the battery and the ACM’s DC input jack. Here are the general schematics of those connections
Note that there are many options available for batteries and chargers, in this example most of the connections are provided by the battery pack and all that is necessary is to connect the charger to the battery and the battery to the ACM.
Sources for the pack and charger: http://p.globalsources.com/IMAGES/PDT/SPEC/561/K1056158561.pdf
This battery pack has a 2.1mm pin socket and the ACM has a 2.5mm pin in the DC input socket so you will need to use an adapter.
Source for the adapter: http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_1953591_-1
With the 2200mAh battery pack we were able to keep an ACM5004-G powered and connected to the cellular network for ~4 hours.