Thanks for the tips, everyone. They're all helpful and I made a lot of notes. Sounds like I have a lot of research left to do!
In the interest of space I won't quote them all individually, but to summarize:
Unfortunately I have to find a solution by tomorrow and I also have my day job, so I don't have enough time to do any real research or shopping, or even to mount 6v batteries if I bought them.
I just checked with my brother-in-law and he can get us free batteries when we're back at home base next month. I'm not sure if he can get 6v GC2s, but we're selling this rig in a few months anyway. Right now I'm more interested in spending a little money on an adequate solution than spending a lot for the "right" one. We just won't recoup any more investments we put into our rig. I'd rather save money so I can invest it in the next one.
I checked the battery connections and they looked pretty corroded so I'll clean them off, as well as looking into any other issues in the system. I have no doubt that the battery is shot, though. It's been completely drained too many times for it not to be.
With all that said, I'm going to go down to Camping World tonight and pick up a cheap Champion portable generator. The one I want is noisy (68db at 23 feet) but it's also $300 instead of $2k+. It should meet our immediate needs. We can run it for an hour or two at night and in the morning to take the load off the battery.
Thanks again to everyone for the help. You guys are great!
