12v inverters----update

I am slower than the 7 yr itch and I wanted to add an update on my backup power system for my beloved PR1 machine---I bought the 12v lighter adapter from CPAP.com...bought the female socket with clips from Radio Shack...got one hell'va deal on 5 new 35AH deep cycle batteries off of Craigslist....going to buy a 2 bank Battery Tender from Amazon for now and later I will buy the 3 panel 45 watt solar panels from harbor freight..this is all taking time because I have to stay on my monthy budget..tks--FA