How to calculate how long a car battery will last as backup

[r_wellwood]

Now that would be a serious backup system. I would consider something like the CanTire system, but going gas? (The portion of Scottish blood in my veins is whispering cheap, cheap, cheap...)

If you get this setup, make sure to post some pictures. Heh, do a test and videotape the whole thing. I would grab some popcorn to watch.

RW