Trolling motor disrupts sonar image

[Towrope]

I have a 1997 Minn Kota model 865, bow mount trolling motor with Auto pilot. When operating it interferes with the sonar picture on my Lowrance Hook 9TS. All other features on the 9TS work fine. They share a new Lithium battery. The cables do not run near each other. Why does this occur and what is the solution? Thank you

 

[alldodge]

Guessing, but trolling motor on the bow means it's stirring up the water, and making bubbles. Sonar can not read thru bubbles nor can a depth finder. But will see if @dingbat knows better

 

[airshot]

Is the transducer in front near the trolling motor or in the rear off the transom ?

 

[dingbat]

I have a 1997 Minn Kota model 865, bow mount trolling motor with Auto pilot. When operating it interferes with the sonar picture on my Lowrance Hook 9TS. All other features on the 9TS work fine. They share a new Lithium battery. The cables do not run near each other. Why does this occur and what is the solution? Thank you

Not much to go on..... you didn't describe the type of interference nor under what conditions it happens.

Where is the transducer mounted?
Trolling motor.......12 or 24 VDC operation?
Install the ferrite on power cable?
Common ground connection between the two units?
A bad or failing electric motor will introduce "noise" into the system.

 

[Towrope]

Not much to go on..... you didn't describe the type of interference nor under what conditions it happens.

Where is the transducer mounted?
Trolling motor.......12 or 24 VDC operation?
Install the ferrite on power cable?
Common ground connection between the two units?
A bad or failing electric motor will introduce "noise" into the system.

Transducer mounted on stern, 12volt, common ground. Unfamiliar with "ferrite on power cable"? Interference consists of most all fish and structure images disappearing while trolling motor is running. Bottom dept still on screen. Sometimes I get vertical lines across full water column. The moment the trolling motor is turned off everything works fine.

 

[dwco5051]

https://support.klipsch.com/hc/en-us/articles/4416949281044-Using-Ferrite-Chokes

 

[cyclops222]

What is the voltage when operating ? Of the trolling motor and the sonar battery ? Do they have their own battery or do they share ?
Is the interference only with the motor running at certain speeds ?

 

[dingbat]

Transducer mounted on stern, 12volt, common ground. Unfamiliar with "ferrite on power cable"? Interference consists of most all fish and structure images disappearing while trolling motor is running. Bottom dept still on screen. Sometimes I get vertical lines across full water column. The moment the trolling motor is turned off everything works fine.

Aluminum boat?
Auto pilot connected to Lowrance as well?
Network cables?

Not ideal to power an electric motor and sonar off a common battery. Especially if it’s “switching” power to minimize battery usage.
Throws off large, electromagnetic pulses with each switch. Only get worst as motor wears

Pull either unit off the common battery and power separately. If the problem goes away, you have an EMI problem

Because of the elevate frequencies in use with side viewing, most come with ferrites for the transducer. Surprised Lowrance didn’t supply a ferrite with the unit

 

[airshot]

Should have seperate batteries for trolling motor and for sonar unit. My MK manual recomends that.

 

[Towrope]

Aluminum boat?
Auto pilot connected to Lowrance as well?
Network cables?

Not ideal to power an electric motor and sonar off a common battery. Especially if it’s “switching” power to minimize battery usage.
Throws off large, electromagnetic pulses with each switch. Only get worst as motor wears

Pull either unit off the common battery and power separately. If the problem goes away, you have an EMI problem

Because of the elevate frequencies in use with side viewing, most come with ferrites for the transducer. Surprised Lowrance didn’t supply a ferrite with the unit

Aluminum boat?
Auto pilot connected to Lowrance as well?
Network cables?

Not ideal to power an electric motor and sonar off a common battery. Especially if it’s “switching” power to minimize battery usage.
Throws off large, electromagnetic pulses with each switch. Only get worst as motor wears

Pull either unit off the common battery and power separately. If the problem goes away, you have an EMI problem

Because of the elevate frequencies in use with side viewing, most come with ferrites for the transducer. Surprised Lowrance didn’t supply a ferrite with the unit

Yes, Aluminum boat. No connection between auto pilot and trolling motor other than a shared power source. No network cables and no ferrite beads. I will use separate power sources and obtain ferrite beads and report back on the results. Thank you all for the excellent suggestions.

 

[mmasco]

Buy the Murata BNX002 electronic component from a radio parts store (Farnell, Mouser, Digi-Key) and install it in the gap in the sonar power cable, as close as possible to the sonar, and ideally in the sonar itself.

It will remove all power supply interference, much more effectively than a ferrite filter.

 

[Towrope]

Well, it took a while to get back on the water. Ferrite filters had no effect but, hooking up to a seperate battery from the trolling motor resolved the issue. Thank You all for the advise.