Yes if it's a fixed mount it's easier, however, don't despair. I think its on page 29 of the manual it shows the "extra" connector, it goes between the 8AA battery pack connector and the plug that goes into the back of the Unit. It's the little receptacle end you might have a bit of a problem finding, usually called a chassis mount connector. Anyway, you can splice 2 more wires into that present short wire connector to get you to your 12V Gell battery, add a 3A fuse and you're good to go. Another method I did for a friend of mine who had a similar one, we carefully soldered 2 wires in parallel to the ones that come out of the 8AA pack to hook up to the 12V battery. You handy with the soldering iron?