# Interference from trolling motor on fishfinder???



## ForkliftJeff (Jun 21, 2010)

I'm headin fishing for a week in a few days and it will be the first time using my new trolling motor and fishfinder. I have a Minn Kota Traxxis 45lb with Maximizer and an Eagle Fisheasy 245 DS fishfinder freshly installed in my 12' Lowe. I'm just reading through the manual for the motor and it says, 
"With the Maximizer speed control, you may, in some applications, experience interference in your depth finder display. We recommend using a seperate deep cycle marine battery for your trolling motor and power the depth finder the the staring/cranking battery."
Now I haven't tested it out yet so it may be fine, but I don't want to get up there and have the fishfinder glitchy for a whole week. Has anybody had a problem like this? I don't want to have to haul around a second battery for the fishfinder.


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## russ010 (Jun 22, 2010)

You should be alright - but, some people have interference and other's don't. I've never had any interference run through any of my fish finders on any of my boats.


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## Zum (Jun 22, 2010)

No interference here as well.
If you do get some(I doubt it)you can buy a filter or a small seperate battery(maybe lawn mower even smaller).Fish finders don't draw much power.


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## longjohn119 (Jun 22, 2010)

If you do run into problems try a couple of those clamp on ferrites from radio shack on the transducer cable
https://www.radioshack.com/product/index.jsp?productId=2996360

Place one as close to the transducer as possible **but not in the water** and place the second one as close to the fishfinder as possible/practical. If they aren't a tight fit then tape or heat shrink them into place. 

Motors give off a lot of high frequency harmonics in the RF frequency range. There are basically two points of ingress into the fish finder for this RF interference, the power cable which is usually already well bypassed by the manufacturer, and the shield of the transducer cable. These ferrites chokes 'choke' off any RF induced into the shield and keeps it off the ground system internal to the fishfinder where it causes interference. 

I also use ferrite cores (a different style though, looks like a donut) on the power lines at the livewell pump motor and the bilge pump motor. Not so much to keep interference out of my fish finders but out of my radios (AM/FM, Marine, Bluetooth, wireless mouse, and cellular data modem) plus in AND out of my computer.

I have more of a problem with the fish finder causing interference to my other devices (Mainly my AM radio during a Cubs game) than I do with something causing interference to my fish finders


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## ForkliftJeff (Jun 23, 2010)

Excellent. Lots of good info. Sounds like I should be ok. 

Another thing just crossed my mind. What should I do with the extra transducer cable? Right now its all just bunched up under my rear seat. Should I just wrap it up neatly in a small bundle (like how it came in the box) and zap strap it out of the way under my seat or will it like to be straightened out a little more.


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## russ010 (Jun 23, 2010)

yep... roll it up so that there won't be any kinks in it and zip tie it in 2 or 3 places, and put it where it won't get touched by anything that could damage it


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