Depth Finder Issue

Each time I turn my trolling motor on, I loose most of the picture on my finder. The depth reading is still present and correct, and the finder continues to show the bottom detail. However, everything between the surface and the bottom (fish, structure, etc.) disappears.

It does not have to do with the speed. I do not have this problem when running the outboard, or being pushed by the wind/current. Also, the transducer cable and the trolling motor power cable are not run parallel, so that is not the issue.

Could it be that the trolling motor and finder are tied to the same battery? Any other ideas? I would appreciate any thoughts you may have.

my fish finder was on the same battery as my trolling motor. I bought a cheap 12v lawn tractor battery to run the fish finder and the problem was solved. The lawn tractor battery will power my Lowrance LMS336iGPS all day without a problem. It's not a deep cycle battery, so I recharge it after each use and it will last 2-3 years. (not bad for a $20 investment).

Your finder should be on your cranking battery! If it's not move it to the cranking battery.

Your trolling motor should be the accessory on your deep cycle battery!

I had a problem like that. When ever I ran my trolling motor it would wack out my sounder, I ran a groung wire from my trolling motor mount to the negative side of the batteries and made the problem go away.

The only thing that should be on the trolling motor battery is the trolling motor. When you step on the tm's go button the initial current draw is high. This causes the voltage to go down. Sensitive electronics in your depth finders do not like that fluxuation in voltage and it can damage them.

I have been running my front mounted fish finders off of the trolling motor battery for 26 years now and never had a problem......also running the front electric anchor off of it. Had it like this for 22 years on my old BassTracker and going on 4 years now with my G3.

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Originally Posted by G-3 Fisherman

I have been running my front mounted fish finders off of the trolling motor battery for 26 years now and never had a problem......also running the front electric anchor off of it. Had it like this for 22 years on my old BassTracker and going on 4 years now with my G3.

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Ground isolation, trolling motor voltage, connector quality, wire size, quality of fish finder, etc. can all effect how much of a problem you will have or won't have. ISBN is right according to the fish finder makers. Doesn't mean what you've been doing ain't right, cause it's been working out great for you. But that doesn't change the problem the OP is having.

I think the OP should look at isolating his fish finder from his trolling motor battery. DC motors are really good electrical "noise" makers.

I run just the TM off one battery... everything else off the starter battery

Its a possibility that the OP's problem is due to some poor wireing connections. I do not care for twisted and taped connections and I certainly do not like the crimp on butt connectors etc. All the connections on my boat are good mechanical connections ( clean and twisted tightly), soldered properly, and then sealed with heat shrink tubing. I would be interested to know....if the OP's problem has been there all along or just recently started.

Simple solution is to move the FF to the cranking batt. Some, like G-3 don't have problems, but the safest bet is to move it. Not everyone can be "Special" like G-3.

Wannabe...