I have a I-Pilot trolling motor and a Humminbird 998cSI. The depth finder is wired directly to the house battery with no switches in line, only a fuse, and the battery is in a rear compartment with the transducer mounted on the transom. The trolling motor batteries are completely separate and are under the center console. When I change speeds on my trolling motor, I get interference on my depth screens including regular and down imaging. It only happens at certain speeds and I can change the speed by a 1/2 number on the I-Pilot remote and it will stop or get better. The only thing the house battery and the trolling motor batteries have in common is the on board charger. Any ideas what’s causing the interference? It doesn’t make sense to me, but could it be the on board charger?
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I’ve seen something similar on a friends boat, except it was the big motor causing interference. His depthfinder had a “noise supressor” in the menu that we had to turn all the way up to stop the false images. We could still mark real fish and bait in water as deep as 45’, possibly deeper, after making the adjustment. It probably affected the sensitivity a little, but atleast we quit marking “ghost fish”. See if you have such an adjustment on your depthfinder. It might be an easy fix if you do. Good luck.
I have a seperate batter I use for my exact same Hummingbird as yours and have no issues. This gives me a backup battery and no interference.
2012 DLV 198 Carolina Skiff
Humingbird 998 Side scan and GPS
GPS trolling motor
My Cherokee indian name is asuvsgi nahna adadudi or Fishes on Credit
It will be simple enough to find out, just disconnect the onboard charger from the house battery. If it goes away, then at least you know where its coming from.
'06 Mckee Craft
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