Topic: ELIMINATING TROLLING MOTOR INTERFERENCE

[metalman]

Despite separate power supplies (batteries), carefully routed wiring and chokes, my trolling motor (24v Minkota Terrova) has has always had an intermittent and varied effect on the display on the display of my 997Si.
 
Certain TM speed setting do nothing while others immediately create havoc on the screen. It seems even the direction the TM is pointing can effect how much interference shows on screen. It's never been a show stopper; more if an irritation I've learned to live with.
Edit. The TM is on the bow, the xducer is on the transom. There are no networking connections and the TM is not connected to the HB unit in any way.

I'm hoping that by the time I get to install my newly ordered Helix unit, I can learn something here that may give me interference-free performance...... if such a thing is possible??

Thank you,

[rnvinc]

There are 2 possible paths of interference encroachment - power circuit or transducer circuit  ...

As you stated the TM is on the bow and the xducer is on the transom - that narrows the encroachment path to the power circuit - somewhere  ...

This can be TM power wires close to HB head unit power wire - common battery - common battery charger etc

Simplifying troubleshooting would be to put a temporary battery right next to the head unit wired direct to head unit  ... this would determine if power wires under the deck are the area of interference encroachment  ...

Rickie

[metalman]

There are 2 possible paths of interference encroachment - power circuit or transducer circuit  ...

As you stated the TM is on the bow and the xducer is on the transom - that narrows the encroachment path to the power circuit - somewhere  ...
This can be TM power wires close to HB head unit power wire - common battery - common battery charger etc
Simplifying troubleshooting would be to put a temporary battery right next to the head unit wired direct to head unit  ... this would determine if power wires under the deck are the area of interference encroachment  ...

Rickie

Rickie,
Thank you for the reply.
I'm not sure what constitutes "too close" but there are no TM cables within 3 feet of the the head unit. I run separate batteries for TM and HB unit. The battery charger is common but the interference is still present with the charger wires entirely disconnected from all batteries.
In the very front of the boat, the TM wires do come close (within a foot) to the wiring for the bow light/front deck light/aux. power plug which ultimately connects to the HB unit via the battery -tive.
I have not yet ran the HB from a temporary dedicated battery situated next to the control head; that would be an easy thing to try.

In a previous attempt to fix this issue, I ran a fused wire between the -tive terminals of the TM and HB batteries and this did reduce the interference by a small but noticeable amount. I also tried running a wire from the TM motor housing to the -tive terminal of the TM battery but it made no noticeable difference.

Thanks.

[rnvinc]

Your troubleshooting steps so far are very valid remedies in some scenarios  ...

Try the battery next to the head unit scenario  ... this will determine if the Humminbird power circuit under the deck is the encroachment area  ...

Rickie

[metalman]

So,
I connected the HB to an external battery but the interference did not change at all.

Currently, this is the set up:
HB connected to external battery.
TM connected to TM batteries.
On board charger completely disconnected from everything.
Transducer wiring rerouted to ensure maximum separation from other wiring with no coils in excess.
Fused bonding wire between TM and cranking battery neg's (presumably a moot point when using external HB battery.... maybe not?)

The TM wiring is a straight shot from the batteries to the bow receptacle and the only place it comes anywhere near the boat wiring is at the small panel at the front where the TM plugs in where there are the bow light wires and and an interior deck light.

Open to any other suggestions.

Thanks

[oschi]

Maybe you have to ground your TM to TM battery.
The coil of the motor is producing a lot of electromagnetic radiation.
I had the same problem with my motorguide.
If you have some spots on the motor nacelle where the paint is gone put a cable (crocodile clamp) on that spot and connect it to TM battery ground (minus). That prevents all that electromagnetic disturbance.
If that works open the motor connect a wire internally to the metal housing.

[metalman]

Maybe you have to ground your TM to TM battery.
The coil of the motor is producing a lot of electromagnetic radiation.
I had the same problem with my motorguide.
If you have some spots on the motor nacelle where the paint is gone put a cable (crocodile clamp) on that spot and connect it to TM battery ground (minus). That prevents all that electromagnetic disturbance.
If that works open the motor connect a wire internally to the metal housing.

Appreciate the suggestion, I've already tried that and it made no noticeable difference.

Thanks,

[rnvinc]

You might want to contact Humminbird and explain all the remedies you’ve tried so far  ...

They might send you some ferrite rings  ...

1-800-633-1468

Rickie