Topic: HELP, I am getting horrible DI and SI interference from my trolling motor

[fishcall]

I just got a brand new boat and can not return it to factory to fix this problem. When ever I turn trolling motor on, I get horrible interference on my DI and SI sonar. Left side of screen is with trolling motor on and right side is after turning it off. As soon as I stop TM from running, the interference disappears. My system consists of 36v Terrova TM connected to a breaker and then connected to 3 batteries. Trolling motor is on bow, Humminbird Helix 10 SI Mega Chirp gen2 in console, and transducer on the stern. The only thing connecting my trolling motor to my house batteries (or anything else on boat) is the Minn Kota Alternator system. This system was designed to be connected this way so I wouldn't think it would be causing the interference. I going to try to disconnect it from the entire system today but wanted to ask if anyone else has had this problem and how did you fix it?

[rnvinc]

Humminbird Customer Service deals with customer interference issues every day  ...

1-800-633-1468

Rickie

[fishcall]

yes, they are sending me a "choke" which don't really understand but I will try it. the difference with my problem is that I do NOT have a transducer on the trolling motor like most others that have had the same problem on this website. My trolling motor is on the bow, the Humminbird unit is in the console, and the transducer is on the stern. I also do not have the trolling motor connected to the Humminbird in any way.

[rnvinc]

yes, they are sending me a "choke" which don't really understand but I will try it. the difference with my problem is that I do NOT have a transducer on the trolling motor like most others that have had the same problem on this website. My trolling motor is on the bow, the Humminbird unit is in the console, and the transducer is on the stern. I also do not have the trolling motor connected to the Humminbird in any way.

There are 2 paths that RFI can encroach into the Sonar system - transducer circuit and/or power circuit  ...

Your noted Setup surely indicates the interference is encroaching thru the power circuit  ...

1 suspect could possibly be a common onboard charger for the trolling motor batteries and the electronics battery  ...

Another suspect is power wires to the trolling motor too close to power wires feeding the electronics  ...
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The "choke" HB is sending is a ferrite ring that works for some and doesn't work for others  ...

Either way the choke doesn't fix your interference problem - it tries to "filter" the interference before it gets to the head unit  ...

The best "fix" for interference is to track down the culprit where it's encroaching into the Sonar system and remedy the encroachment point  ...

Rickie

[fishcall]

the inline choke that Humminbird sent eliminated the problem. This is the choke that goes between the onboard charger (for house) and one of the house batteries. They also had a HUGE negative wire connected between the negative of the 36v system and a negative to one of the house batteries. This is needed for the digital battery gauge to work correctly. I replaced it with  much small gauge wire and added the choke, no more interference.