Yesterday I took my boat out on the lake, I used one of my trolling motors. My lights are all wired together and they all hook into a fuse (15 amp) before going to the battery (12v) I've tested the lights a hundred times, I've left them on for hours- no problem. I clamped my trolling motor (30 lb.thrust) onto the same battery and I noticed my lights fizzled out. The trolling motor ran fine for the 4 hour period I was out, I came home checked the battery level it was just below half, I checked the fuse and it was blown, replaced it and the lights are fine, I even left the lights on for 2 hours for good measure. Why would the fuse blow by hooking up the trolling motor to the same battery? The trolling motor was clamped to the main posts, and the lights are hooked under the wing nuts on the battery. I just don't get why this would effect my lights as a total seperate hook-up to the battery? ANY ADVICE WOULD HELP! Thanks D.

By any chance was your TM accidentally set to the "ON" position when you first hooked it up to the battery?  If so, the sudden amperage spike may have taken out the fuse for the lights.  That's the only explanation I can think of at the moment.

No Mike, I remember hooking up the tm in the driveway before I left, I remember making sure the knob was turned to off before I hooked it up and clamped it on the back. The pos. and neg. for the lights were already hooked to the battery and they run through the fuse up the the 4 switch box, and all were turned off till I checked them on the water. I think this week I'll hook both up in the backyard and see what happens? If it blows the fuse again, do you think maybe a 20 amp fuse might do the trick? This is very strange. :-?

Based on what you are saying you have a problem with the circuitry for the lights. Increasing the fuse side could have quite nasty results. Find the problem.

Del, I am alternately scratching my head and my butt.  If you have an ohm meter, measure the resistance in your lighting circuit and get back to us.  Attach the meter to the positive and negative leads of your light circuit while not connected to the battery.

I thought the norm for a TM was a 30 amp fuse alone. I saw you tested the lights, did you by chance have the TM connected and running at the same time.