Question about Battery Backup

I have a question about the battery backup.  Does it work for a maximum of 8 hours total or 8 hours of talk time? That is, if I lose my power at noon today, will the battery backup be done by around 8 pm? Or could I keep it going for a few days as long if I do not use the phone? I have been told conflicting information so I wanted to clarify.  Thanks.

2 Replies
Contributor - Level 3

mmuller ,

The Battery Backup supports voice service for 8 hours.  This will be 8 hours regardless to whether you are talking or not talking.  The battery is constantly charging and  it loses charge after 8 hours.    Please see the following link for more information.


Tonya D.

Enthusiast - Level 1

Hello Tonya D,

>This will be 8 hours regardless to whether you are talking or not talking.

Sorry, that is not correct. Verizon says only that the battery provides up to eight hours. The actual time is indeed affected by phone usage and by other things, including:

  • The condition of the battery, meaning whether it is near the end of its life. The older the battery, the less charge it can hold. In addition, each time that the battery is heavily discharged and left uncharged (as during a prolonged outage after a storm), some of its capacity is permanently lost. This an inherent characteristic of lead-acid batteries.
  • The air temperature. In cold weather, if the battery is located in an unheated area, its capacity will be less that it will be at normal room temperature. The nominal eight hours assumes room temperature.
  • The number of telephone sets in a house that are connected to the FIOS line.  Incoming calls use lots of power for ringing, less for talking and dialing. The more phones connected (and the longer that they ring), the faster the battery discharges as calls come in.
  • The number of calls made and received. Each call consumes power from the battery, which cannot recharge until AC power is restored.

With all these variables, you can see that it is not possible to predict the number of hours of phone service that will be available. Users should be made aware of this and should understand that the nominal eight hours is just a rough estimate, not a number that they can count on.

Fortunately, after the ONT shuts down due to partial battery discharge, about one additional hour of bi-directional phone use is available by pressing the emergency use button on the backup unit.

Doug M. in NJ