Interference from TM to from SI unit

[Wayne Gatt]

Hi, I as most have an issue between the trolling motor and my Hummingbird SI unit picking up interference. I have the filter on the wiring for the TM and the power cord for the SI unit has a filter on it.

I’m wondering if anyone has come up with a solution the works better than these do?

I heard that strapping the three TM batteries negative posts to the main battery’s negative post should do the trick, but unsure if that’s a good idea. Any thoughts?

[blkfalc4]

If you have an onboard charger, try disconnecting the starter battery charger leads and check results.

Do you have a jumper switch for the main battery also?

[grout-scout]

Do NOT hook the TM grounds to the cranking ground!

[Wayne P.]

Do NOT hook the TM grounds to the cranking ground!

Do NOT connect the trolling motor neutrals to each other either. Two of those connections are a dead short to positive and negative.

[billnorman1]

Do NOT connect the trolling motor neutrals to each other either. Two of those connections are a dead short to positive and negative.

That's for sure. It would be the 4th of July inside the hull.

[DougL58]

http://www.bbcboards.net/showthread....t=ferrite+ring

[Jonestrollingmotor]

Do NOT connect the trolling motor neutrals to each other either. Two of those connections are a dead short to positive and negative.

One thing for sure, he won't be able to connect all the grounds cause when he does one, it will cause the short since the batteries are in a series connection.
Depending on the trollingmotor, it's not a good idea to connect any grounds to the cranking, but if he does, it needs to be the ground post common with the trollng motor ground