Portable power supply need help

Hi:
Thank you for reading this message. I am scheduled to go to a star party later this month and wanted some help about portable power supply. I am planning on running a Losmandy G11 mount, a SBIG camera (2000XM), laptop and Kendrick Dew removing system. Can anyone help and tell me what type of battery/power source I should purchase and where I can get them. I am hoping to image and run my system for 10 to 12 hours.
I sincerely appreciate your help
Ashton

That's a pretty good load with all devices powered up, guessing 5 to 8 amps. Plus you will want separate power for the SBIG camera unless using a relay box, right? Don't buy the minimum capacity, because you will need reserve for colder weather and discharge between charging times. Factor in the cost of a good charging unit if not included.

Assuming 75% duty at the highest rate, the lowest cost solution would be a 50AH to 80AH deep cycle battery (Batteries Plus, WalMart, Sam's Club, Sears, etc.). [AH = amp hours] These will give you the most capacity per dollar, but are heavy and not packaged for portability. Most are not true "deep cycle" units that can handle 80% draw down, but they are a good start and readily available. RV and golf cart dealers have the real thing, but they are expensive. If you go this route, learn care and feeding of the battery (charging), usually lead acid.

Kendrick makes a very nice 12V 33AH battery in a package for astronomers with built in voltmeter, but it is not cheap ($300+).

I use two 12V 17AH jump start style batteries (usually yellow case), which are about $30 each at home stores and easy to move around for a G-11, Kendrick heaters, and ST-237, but I don't go for 12 hours!

Two more things...use fuses on all your gear. It is very easy to fry a Losmandy digital drive board. And test your rig before going in the field.