Thread: A Sample Timer (Need Help)

Hi, i'm new to forum and will be great full if somebody help me with this matter.
my need is a timer to to the following:
first the usage environment: a APS connected to home electricity to provide emergency light.
the need of the time is just when the main electricity gone he will turn on the APS for 5 min, then if the reset button pushed it will continue to run till the electricity come again and so on.
i don't know who to write them in electronic way, but u get my idea which is to protect the batteries from running empty if there was no body at home and APS left powered on.
many thanks

Many Thanks for your reply, i already have a low-battery indicator which stops the APS when battery get empty, but this is my needs, the aim is to save the battery for ex:
- main power on, APS Charging, no timer triggered
- Main power OFF, APS starts to work for 5 min and continue working if reset button pressed
-main power On again, APS Charging, No timer triggered.

scenario: suppose u are not at home and there is main power, after a while the power goes off, so the APS will start to work without any interrupt till batteries get empty, so if u put a timer triggers this u will save battery life.

many thanks

thank Boncuk for reply, i know its easy to turn off the APS, what if a u for reason u forget to do this (or have a wife know nothing about these things!!!) ??????... and to get on hard work and modify the APS it will be so expensive !!!, i thought this idea will be sample and powerful (I think) and takes no time to build it and install it... i drew a schema (don't laugh..
i will remove the APS Power Button and replace it with the time..
thank again