[CA] [CA11] Trouble Adding Tacktick T122 to Existing System

[bobcat]

It is likely past warranty (unit is dated 2010) and the highest battery voltage I've seen is < 5v after charging for a week. Also the battery voltage drops like a rock when unplugged from the 12v source.

Given this does it still make sense to sent it to Raymarine or should I just order a TA119 3-up battery pack?

Also a few other T122 questions:

*Why does it have a 2 separate NMEA inputs? In particular is there something special about the input labeled GPS NEMA1 vs ALARM NEMA2? (i.e. can they be used for any 0183 instrument?)

*What is the purpose for the GPS PWR out?

Thanks for your help.