Trolling motor Transducer grounding

[Jetboy]

If I’m getting intferance on my HDS and I’m going to ground the transducer bracket at the bottom of the trolling motor. Do I hook it to the 12v HDS ground? Or to the 36v trolling motor ground? Are they separate grounds ? Or is ground ground?

[billnorman1]

Ground is only ground to the same source of not ground or usually, Positive. Most transducers do not have a ground contact, unless I'm wrong, they are totally encapsulated in an insulator.
For instance, if you had a spare battery in your car or truck, and connected the positive terminal to your car frame, which is "ground" to your alternator, nothing would happen, no sparks no short circuit because that chassis ground is not common to that spare battery.

[Jetboy]

I’m grounding the bracket that holds the transducer. As I’m getting noise or interference each time hit the trolling motor botton.
‘I found it on you tube. It’s the 12v ground same as the HDS. It seems.

[Jonestrollingmotor]

Your signature shows a Motorguide X5. If that is the trolling motor you have, the lower unit of the trolling motor is not grounded, anywhere. Internally, the wires go to the brushes. Externally, it is on the end of a composite shaft. Does you tube not tell you where to get the source of the ground wire?
That being said, on the motorguide the source of interference can come from several different sources, from the control board, to the wiring, to the motor itself. Running a ground wire from the trolling motor ground source (you'll find that under the footpedal / black wire) to a bare spot on the skeg may help and is a place to start

[hookbender]

Your signature shows a Motorguide X5. If that is the trolling motor you have, the lower unit of the trolling motor is not grounded, anywhere. Internally, the wires go to the brushes. Externally, it is on the end of a composite shaft. Does you tube not tell you where to get the source of the ground wire?
That being said, on the motorguide the source of interference can come from several different sources, from the control board, to the wiring, to the motor itself. Running a ground wire from the trolling motor ground source (you'll find that under the footpedal / black wire) to a bare spot on the skeg may help and is a place to start

Is this true for Minnkota?

[Jonestrollingmotor]

Some MinnKota's already have the bonding wire in place. If not, it needs to be connected to the ground side of the light wire. The light wires come off the control board, but are also in the head of the trolling motor.

[Jetboy]

I’m installing a new ultrex. And was just going to be pro active as I was having trouble from the MG.
i read in the manual that the Mk is grounded but I figured I would just run a wire while I’m rigging up,the new stuff.
i have not seen any grounding videos specific to the ultrex.

[Jonestrollingmotor]

the Ultrex is grounded. DO NOT run a separate ground. If you do, you risk causing a short through the transducer and depthfinder.

[C.Warrix]

What about a Motorguide Tour 24 v motor? I'm getting interference on my Humminbird 999 SI DI

[Jetboy]

Thanks I’ll remove it. Before I mess it up.

[CHTXK]

Having issues with Helix 10 SI getting interfere on SI & DI when TM prop is running on my Ultrex. HB tech told me to run ground wire from tm skeg to tm battery neg terminal 08/02/18 ? Would you recommend proceeding with separate ground? Have XHS 9 HDSI 180 T transducer (not using Ultrex US2), latest PC11 power connectors, choke installed between charger and battery, 24V -80LB Ultrex on separate TM batteries, HB sending me ferrite ring to add. Appreciate any help...…. thanks

[Bradrodfish]

Having issues with Helix 10 SI getting interfere on SI & DI when TM prop is running on my Ultrex. HB tech told me to run ground wire from tm skeg to tm battery neg terminal 08/02/18 ? Would you recommend proceeding with separate ground? Have XHS 9 HDSI 180 T transducer (not using Ultrex US2), latest PC11 power connectors, choke installed between charger and battery, 24V -80LB Ultrex on separate TM batteries, HB sending me ferrite ring to add. Appreciate any help...…. thanks

Like John said above do not run a separate ground from the Troll motor Skeg as U Tube subscribes. It will mess things worse. The Ground is already inside the Ultrex. I would however add the ferrite ring that HB recommended. I would also check the fuse inside the troll motor head. It could be blown.

[Lou r Pitcher]

A so called "short" involves introducing an undesired electrical pathway between a powered positive voltage area of a circuit and the negative (or sometimes called ground) side of the power source(battery) .

Adding the above wires described above to a US2 installation is done in an attempt to create a Faraday RF shield effect around the lower trolling motor unit. This will though not introduce a concern for a true "electrical "short" , but could result in an undesirable overload current condition with interrupted TM power flowing on signal grade wiring.......

Adding the additional negative "ground wire" to the trolling motor cited earlier adds a 2nd parallel current return path to the normal high ampere trolling motor negative wiring that carries the full trolling motor current. This added parallel path would be permit TM motor currents through the transducer cable shield, the sonar unit, along its negative connection to the cranking battery and through any common bonding of the cranking battery negative with a trolling motor battery.

This added pathway, though on the negative power side involves delicate sonar signal shield and small ampere power wiring and must be protected (fused) in the event the circuit carrying power to the negative trolling motor battery connection is ever suspect or interrupted.

In such an instance, up to 50 or more trolling motor amps would attempt to flow on the delicate US2 transducer shield and the small negative power wiring of the sonar.

[MichAngler]

Looking at this from the other side of the coin
If the Ultrex is already grounded might this be the source of my RF noise

I have a Solix with the standard transducer SI/DI/2D powered by a standalone battery that does not use the same charger the only vesical connection is at the transducer bracket (TSS aluminum bracket and 2 metal hose clamps)

I have routed the transducer cable away from the Trolling motor power wires the only proximity is up the shaft of the motor and at the motors lower unit
Since the transducer is mounted to the TSS bracket with metal screws directly into the transducer is it possible there is a connection made providing a source for the noise?

Note: I have a “Link” system but have tested it without the link connected and still see the noise

I was thinking of putting a rubber sheet between the TSS bracket and motor housing and using large plastic Zip Ties eliminating any possible metal to metal connection from the motor and transducer

[CHTXK]

The fuse in the Ultrex head is good. I am not using the US2 from tm and have the unconnected transducer cable tucked up in tm head, could this pick up unwanted rf and noise? I was wondering where the mentioned internal jumper was. I put ohm meter on tm motor housing and poked around top tm head but could not find any continuity. Seems like there should be a ground wire coming up through the carbon fiber shaft to complete circuit (is it the brown wire going to tm head fuse?) With Helix 10 SI in simulator mode I could still see interference on screen in DI and SI when tm prop turned on, but nothing close to when is in water in normal mode. Finally, when I changed transducers in network (switched H10 unit to transd from H9 mega) got clear picks in DI and SI with very min intefer. When I switched the H9 head to the H10 HDSI transd, got TONS of intefer in both DI and SI (still in sim mode). The DI pic was heavily distorted and had white breaks in Di image. The Si screen was distorted too. Using blue screen had white lines approx. 1/4" apart across left and right sides. Both images in 800. The H9 Mega didn't like anything coming from H10 SI unit. Could this mean that my xhs 9 hdsi 180 T transducer id bad? thanks again for your help.

[Lou r Pitcher]

A good fuse supports that the Faraday shield effect may be present and if so is reducing/eliminating RF radiating from the lower unit motor. As Mr Jones mentioned earlier, not all TM interference comes from the trolling motor's lower unit. The TM's circuit board and wiring can be an RFI source.

If US2 is being left disconnected, then seems it is not in the path causing RFI to be delivered to the sonar.

[Jonestrollingmotor]

As mentioned above, with the US2 cable disconnected, it will have nothing to do with the interference you're experiencing. I also don't think it's a bad transducer, although it could be a bad transducer cable. RF can enter anywhere the ground shield is broke. The control board emits certain frequencies and usually it's the DI/SI (455/800khz) that has the worst interference. The only way I've seen these resolved it through the addition of chokes and ferrite rings.

[Rick Wilson]

Hello all, I am installing an 36v112 Ultrex with MDI on my boat that has a Stelth charging system that has a common ground for 12v and 36v. Minn Kota notes caution with the ultrex having a common ground. any Idea what I do now? really don't want to buy Minn-kota charging system. Please give me your thoughts?

[SoonerFan]

I’m installing a new ultrex. And was just going to be pro active as I was having trouble from the MG.
i read in the manual that the Mk is grounded but I figured I would just run a wire while I’m rigging up,the new stuff.
i have not seen any grounding videos specific to the ultrex.

I did that and it didn't help one bit. I grounded it to the starting battery, not one of the TM batteries. I talked to Minn Kota several times and they sent me a big choke...that stopped the spurious emissions.



That thing weighs at least a pound or two!

There are things you should do if you haven't already...
1. Make sure that the cables that run to the trolling motor batteries are run on a different side of the boat from your wire powering the sonar. P I A I know but the big motor batteries throw off a lot of unwanted interference.
2. Run completely different wiring for your sonar all the way back to the battery. Don't tap into OEM boat wiring.
3. Excess transducer cable should be coiled and then twisted into a figure 8 and zip tied or taped. Stash that up in the bow as far away from other wiring as you can.
4. Try a ferrite ring. There are a bunch of different ones. I got mine on Amazon.

Here is a link to the very informative discussion I had a few years ago when I was going through the same thing you are. Here you will find some sage advice from the late & great John Jones.... http://www.bbcboards.net/showthread....570&highlight=