Replaced 520t Battery Backup

I searched on here and found a few different people who had problems with the DEI 520T battery backup not working %100. Sometimes when the main vehicle battery was disconnected, the alarm wouldn't trip. None of those topics determined the actual problem or resolved it. I had recently installed a bb on my viper 5900. I bought the kit off ebay so who knows how long and where is had been sitting around. The alarm wouldn't go off when the main battery was disconnected and sometimes the siren wouldn't run either. The voltage on the battery was around 11.29 and I tried to charge it with my triton charger (used for R/C planes etc) and it wouldn't take a charge. I also left it hooked up in the vehicle for a few days of driving and still wasn't working. So I went and bought a power sonic 2.8Ah sealed battery and installed that. Tested it out today and the backup system is working great. The battery is larger but I am still able to hide it easily. Just thought I would share for anyone searching in the future.