Interference from big motor?

[Ken Hathcock]

I have a 73sv, it all of sudden started getting vertical lines on traditional screen from the merc. The power source is from the trolling battery. there is no connection between the two.

[Larry3215]

You're saying the power source for the 73 is the trolling motor battery and NOT the starting battery?


The rest of this doesnt really apply until you answer that first question..... but Im going to leave it here anyway so I dont have to re-type it if its needed :)


You're sure you dont have an onboard charger or combiner or ACR with any common connections between the starting battery and the trolling motor battery? No common ground even?

You can double check with a volt/ohm meter.

First, have everything OFF except the main battery switch to ON. Set the meter to volts and touch the leads to the ground terminal on the starting battery and the ground terminal on the trolling motor battery. It should read zero even on the 1 volt scale.

If and ONLY if it reads zero, then change it to read Ohms and do the same thing. If it reads anything at all other than infinity, you have a common ground.

Then, check the battery terminals on the starting battery very carefully for any corrosion - especially where the starting leads from the main connect. Then check all the power leads inside the cowling for corrosion especially around the regulator if there is one.