Hi gang, I'm new to this forum so please excuse my ignorance....(I am Cornish!!!) My question is... I've just purchased a Garmin 300c F/F for my Perception Kayak. How do you power it - what I mean is what type of power output battery/batteries do I need for a 6-8 hour fishing trip? Do I have to discharge the battery to prolong its life? Would very much appreciate any advise you may have. Thanks.