If the power goes out while you are charging your battery, a manual charger will keep charging as if it was just turned on, but an automatic charger may or may not continue charging depending on where it was at in the charging process when the power went out. If the battery is still sufficiently discharged, the charger will continue to charge the battery, but if the battery was almost fully charged, the charger may go into maintain mode early. This only affects the battery in how long it will take to be fully charged. You may also have to readjust the settings because the charger will come back on with the default settings.