Lowrance 332C/Gps.
Getting darker colors with some black dots over 6 mph. With the perko switch I can run each battery individually to start boat and run electronis or draw from both batteries at same time.
Unit is hooked into console dash switch and I think I am picking up some electrical noise/interferance.
Can I hook unit so I have option of using one/either/both batteries and still eliminate interfearance ?
I would try and re wire the unit away from the console I think if you get out of that bundle of wires and hook to the battery by it's self you should be ok.I think if it's electrcal interfearance just hooking it alone you would see a difference.Make sure you ducer is not getting air from under your boat.which side do you have the ducer on make sure it's as far away from your main motor as you can get away with.It sounds like possable air in the back of the boat because that will cause a loss of signal also.I don't know but it's just a couple of thoughts.Hope this helps
Erin has a good point -- cavitation / bubbles from the bottom of the boat or motor can cause you to have intermittent 'ducer noise issues dependiong on where / how you mounted the 'ducer. Sounds like you may have two issues going on -- one is potential "EMR" (electro-magnetic interference) from the power connection, the other being how the 'ducer is mounted.
I wouldn't change any thing.Hook your finder up to one battery(make sure the wires are not next to your motor or boat wires keep them as far away as you can)then switch to the other battery to start the motor and see if the noise goes away.If not you have to try to find out where the noise is coming from,so hook up to the new battery see if that works if it doesn't double check to see if your ducer is mounted right.It should be away from the big motor,it should be away from as many rivets as you can if the boat is an aluminum(just make sure it not right behind a skate on the bottom of the boat)and it should be 1/8 inch below the bottom of the boat.That should be it if not there might be other issue.But do it by process of alimentation.Between every one on this site we should get you up and running.Just my 2 cents.Somebody might be able to fix your problem first time but This is the best I can give you with out seeing the boat.Hope this helps.Good luck.
If you determine that the transducer is not the cause of your interference, you can try placing a ferrite choke core on the power lines, positive and negative leads, before you rewire. Radio Shack also has a closed ferrite that you can wind the power leads on. I have used these before and was effective, but every case is different. Ferrite Core
If you get to the point of rewiring,try to wire the Sonar positive to the Battery Switch terminal that the Battery Switch feeds the console and wire the negative to the battery, this way you still have the function of the Battery Switch. If that does not work than wire it directly to the spare battery.
