I bought a Minn Kota 36 & a group 24 deep cycle battery from Walmart, also a plastic battery box to fit the battery.

I am concerned about having the trolling motor & battery connection inside the battery box.  The box has 4 openings on the lid for the battery to "breath".  Now I know that water will seep in the box, cuz of the openings on the lid.

So, if water gets inside the battery box, will the water short out the trolling motor, or will it still work?

I don't know if I need to put a plastic trash bag around the battery while inside the battery box while I'm the water.

What do you guys think???

The water won't short out your battery.  It could rust the connection points of your trolling motor wires and battery terminals.  This can lead to loss of motor power and faulty charging of the battery.  

Some water splashing on the battery during use shouldn't be a problem.  If you the battery becomes submerged, you probably have a bigger problem to worry about.

Wipe the battery down after use and store it in a dry place.  Promptly clean off any signs of rust and you should be a ok.

You should be fine no matter what... Batteries get charged off of water.. I know they get charged off of Distilled water but its still water. I had an older boat that I let go to crap and it filled with water and submerged my batteries and once I came around to taking care of the boat again the batteries still worked fine. I don't have those batteries no more nor do I have the boat but the Batteries still lasted me about 2 years after the water incident.

If you ever have any problems with corrosion on your batteries just take some good ole Coca-Cola and pour it on the connections... Coke has so much acid in it that it will actually clean your batteries extremely well.

Hope this helped

Drill some holes in the corners and everthing will be good.

Garnet