When the power quits, Surefire 512H takes over.
When it is used with a common 90 A-hr, deep cycle marine battery,
its highly efficient circuitry provides approximately 8 hours of
operation from a wood pellet stove or stoker in the absence of electricity.

It also works with automatic ignition stoves.

Here is how it works:
The Surefire 512H interfaces between a pellet stove or grain stove and the
AC electrical supply. When electricity is present, the Surefire 512H charges a
battery and surveys the power line. At the instant that a power failure occurs,
the Surefire 512H converts the energy stored in the battery to the AC power.
This assures operation of the stove without interruption during the absence of electricity.
When AC utility power is restored, the Surefire 512H reinstates AC utility power
as the prime energy source to operate the pellet stove or coal stoker.
Simultaneously and automatically the Surefire 512H commences the recharging
of the battery, to return it to full capacity in preparation for the next power failure.

Harman Battery Backup For Pellet & Grain Stoves Brochure