dei 520t backup battery

I have this module installed with my alarm system and to spec. I went to test it today and disconnected the power to the battery and noticed that the siren does not chirp or sound as load as when connected to battery. The lights will flash somewhat dimmer. I also tried arming and disarming the system with my remote when it was disconnected and it was having a hard time communicating with the system. Is this normal or do I have a bad ground possibly? Too many things connected to the alarm for the backup battery to handle? The 520T only a few months old and tests at 12v on meter.  Thanks

The parking lights should not flash if you disconnect the battery and trigger the alarm. I could tell you how to wire it, but you didn't say what you have for a vehicle. Did you use a (+) or (-) output on the alarm for parking lights. You should only use negative when using a 520T.

Even though I've installed just a few of those, I was thinking the same thing. That small battery wouldn't have enough power to flash the car's lights for very long at all. You definitely want it set up so that the battery only serves to provide power to the alarm, and the siren, and nothing more.