Trolling motor interference

[Mikeyman104]

My bow mounted trolling motor causes a crazy amount of interference with my Garmin Echomap. I have to turn the gain way down to get some clarity but was wondering if any one has any tips to help limit the inference. The pic is when I was using my trolling motor to move and then when I stopped. 

[Mikeyman104]

Update: after googling and checking my set up, it looks like i forgot to install a ferrite bead so I'll toss that on the transducer cable near the head unit and hopefully that helps clear up the picture.  

[Shakemsam]

Are you using the TM transducer, or the FF's?

[Mikeyman104]

10 hours ago, Shakemsam said:

Are you using the TM transducer, or the FF's?

The fish finders. The TM has a universal one built into it but it's not connected to any display or anything.

[Shakemsam]

2 hours ago, Mikeyman104 said:

The fish finders. The TM has a universal one built into it but it's not connected to any display or anything.

If you're running the FF on the TM battery, that could be your problem.

[Wargofam]

My two cents on sonar interference:

 

What to look for when experiencing sonar interference issues:

•Use good quality resistor type spark plugs with shielded spark plug wires

•Air under transducer (bubbles, prop wash, turbulence, etc.) – avoid strake and chine areas

•Transducers mounted too close together

•Transducer cables bundled too close to nearby power cables (coupling and crosstalk)

•Poor grounding of electronics (this is a biggie!)

•Clean battery terminals and contacts, recommend dielectric grease to ensure good contact and prevent oxidation

•Good idea to run dedicated power to all your individual electronics, and not share power off the same branch circuit

•Always best to power an electric trolling motor using its own dedicated battery/batteries

•Excess transducer cabling (keep away from alternators and other sources of EMI)

•Bundle excess cables in a “Figure 8” instead of creating big loops of cable

•Low battery/alternator voltage will cause LOTS of problems!

•Interference from multiple transducers using the same frequency

•Inspect sonar transducers and cables for damage (e.g., debris, cracking, zip ties, etc.)

•Underwater LED lighting can sometimes interfere with sonar

•Sonar settings:

1. Traveling at high speeds through the water compresses sonar information. Recommend increasing the scroll speed on your display to stretch out the sonar returns for a better picture. Just be sure to revert your settings when you slow down for trolling as too high of a ping rate will blur out returns.
2. Increase gain, but not too much that you start amplifying clutter
3. Increase “Ping” rate – this effectively increases beam coverage in the water
4. Adjust sensitivity every day to optimize the water conditions for the day

 

All that said, I would avoid using a ferrite core on the transducer cable, as this would likely filter out some of the high-speed sonar data streaming from the transducer to the display unit, resulting in an additional problem.  Rather, you'd be much better off placing that ferrite core on the incoming power cable to the sonar display unit.

 

Hope this helps.

[bluegiller]

if you have a Minn Kota motor check the 3 amp fuse ..this video shows it ..mine blows from time to time and when it does I cant run my motor and depth finder at the same time 

 

 

[Mikeyman104]

Thanks all! Trolling motor is on it's own 24v system and Garmin is on it's own 12v system so didn't think they would really interfere with each other. Only got the one transducer on the back that goes to the Garmin and the transducer on the trolling motor isn't plugged into anything right now. 

 

Actually went out on Oneida last night and while running the trolling motor I didn't have any interference that I could notice. However, I was only in 15 FOW so think that's the bigger reason i didn't notice anything. We'll see what happens when I go out again in a deeper body of water. 

[Mikeyman104]

Took the boat out of oswego last Friday and the interference was pretty bad still. I wasn't catching anything, so I played around with the settings in the fish finder with no significant changes. However, I did determine that the interference is coming only when the bow mounted trolling motor propeller is engaged. At low speeds it isn't bad, but at high speeds, which I needed to keep me steering properly in the waves, it was significant. 

 

The fish finder is on its own dedicated battery, and the 24v bow mounted trolling motor is on its own batteries too. I added the ferrite core and the tranducer cable isn't next to any other power cables. Also, I checked the 3 amp fuse in the trolling motor head and put a meter to the fuse and it was still good. The terrova has a transducer in it but I don't have it connected to anything. 

 

Was reading about adding a grounding wire for the trolling motor but sounds like this needs to be done at a Minn kota service center. Anyone have any experience trying this? 

[HB2]

My depth finder was experiencing this same thing . Also my depth raider was squirrely also . I put a nose filter on my gas kicker and it all  went away . 

 

Maybe you could put one on your negative an positive leads on you depth finder or trolling motor . 

[Mikeyman104]

After doing some more reading online, I think I got it figured out. My 2 trolling motor batteries and my Garmin battery were all separate, except for the fact that I had a 3 bank ProMariner battery charger on all these batteries. I wouldn't have thought that this charger was essentially back feeding the noise from the trolling motor to the Garmin battery, but apparently it did because once I disconnected the bank charger from everything, no more interference from the trolling motor. 

 

Thanks all for the responses and help troubleshooting this issue!