On the power issue, I found mixed results on the Lowrance Elite 4x. I made a battery pack that held 10AA batteries. The first set I used ran for about 12 hours total. However, after that when I turned the unit off I didn't disconnect the batts and I think there was some 'phantom' drain occuring, so I went through a set of batteries in about 4 hours when it was on.  My buddy and I did some math on it and decided that 10 D cells would give us the best weight,cost, and run time compared to a 12V motorcycle battery.