I don't know if the system runs indendently from it's own battery or not.
However, the remote is a common application coin cell which I have.
https://my.lojack.com/Documents/Battery%20Replacement%20auto.pdf
The unit is self-powered, and the battery is expected to last 7 years.
I just had this installed. Took about an hour to figure out where to install it.
Cost with the discount was $295, and the extended warranty was another $99. During my discussions with the sale person, I was told about the periodic checks, which they do every 2 years. Big surprise was not conveyed to me at that time was that service fee for that was an additional $99 to come out for the 3 minute check.
Its good for peace of mind. Now I just hope I never have to use it.