is it difficult to wire in a second battery? my lights love the juice.

 

That should be a fairly easy modification. As I am sure you know you will need to wire the batteries in parallel. Pos to Pos, and Neg to Neg. otherwise you will end up with a 24v system.

I was thinking of doing the same, but for a different reason.

I have the MyGig system, and my son knows it plays DVD's. So I am worried that I will be talked into running my battery dead on my next camping trip. So let me know how yours turns out, and show some pics

 

Look up hellroaring technology, they have kits that make it easy. I believe painless also has one.

 

are they expensive?