At the repeater site we have incorporated a battery-backup system in the event of a power failure. This consists of an APC XS-1500 UPS with 2 external 120AH gel-cell batteries. This will give us an approximate run-time of 6 hours minimum with normal use.
When there is a power failure at the site, the repeater controller makes some changes in how the system operates.
First, the repeater hang-time is reduced to 1 second from 5 seconds.
Second, the letter 'B' in CW is appended to the end of the repeater hang-time.
When you are using the repeater during a power failure, when you un-key your mic, you will hear the courtesy tone, a 1 second delay, then the letter 'B'. This is to let everyone know that the repeater is on battery power and to keep your transmissions short (if possible).
During extended power outages, which are very rare, we have a small generator available.