I use car battery for power supply. Its second hand one that cant be used for car anymore cos it has only 150 CCA (Cold cranking Amps) but more than enough to run EK box for whole week
. Its small narrow battery that easy fits next to handle of my Bintel Dob base. I put one screw on opposite side of handle and wrap peace of cable to secure the battery in place.
If you go to any mechanical shop and ask for second hand battery from Toyota Corolla or some other small one they will give it to you maybe even for free.
About serial port; I use serial to USB cable converter that I bought from Jaycar. There is model number here somewhere on this topic I left before. It works great!
The good thing about car battery I use home made dew heaters as well and next day check the voltage and its still 12V! I do have battery charger that can be bought for around $40 dollars.
I got Eee PC Asus netbook that runs CDC software on it. The battery lasts anywhere from 7-9 hours! I got it from Office Works for $379 dollars with Win HP.
Everything works great, thanks to Bojan and Simon for their help! And other guys here who are always willing to give you advice.
cheers
bob