I have a PCM 650VA UPS with a small battery (7AH) which give about 5 mins backup time. I was wondering if I can attach a bigger battery for longer backup time (about 1 hr). has any one tried this here? of course this would mean getting more powerful charger for the battery but as far as i have read they require deep cycle batteries which are really expensive. i would like to hear from some one who have actually succeeded with the Volta/Osaka UPS batteries.