Radio/Electrical issue

[Mylo53]

I have a Bass Tracker Panfish. Over the years I've added a few electrical accessories, such as extra lights, am/fm radio, battery charger, etc. I have two batteries, cranking and trolling. Initially, everything was hooked up to cranking battery and only trolling motor to trolling battery. Over the years I've moved the power supplies to accessories from one battery to another. I've even hooked the batteries up in series (or is it paralell?) so the engine could recharge both batteries at once or the charger could do it. The radio is wired directly to the cranking battery now.
One thing I have always noticed is that when I am fishing/floating and have the radio on, usually AM for talk radio, that if I start the engine, that I almost totally lose volume from the radio. It never goes off, just the volume is so low it can't be heard no matter how much I up the volume. Now, this only happens in AM, not FM. It also happens when I use the bow mount trolling motor. Never had an issue with other accessories not working properly, just the radio while on AM.
I am thinking interferance of some sort, just don't know where/how to look for it. I thought maybe this year that I would put a buss bar near the batteries and then install all the power supplies there to see if the problem would be eliminated. Could it be that the motor electrical "noise" is interfering with a weak AM signal? I use a rubber duckie type antennea mounted on the back cornernear the motor.
Since I am a talk radio "nut" (there I said it) it is annoying to me not to hear my favorite hosts. Any ideas? Or should I just use my iphone with iHeart radio app? (just kidding).
Thanks

 

[Silvertip]

Re: Radio/Electrical issue

First -- put the radio, lights, etc back the way you had them originally -- on the starting battery. Use the troller battery for it's intended purpose -- runing the troller. If you wanted both batteries to charge from the engine the batteries would need to be wired in "parallel". Series provides 24 volts. Try routing the radio power cable (+12 volt and ground wires) away from the engine and the engine harness as far as possible to eliminate interference. Radio Shack also sells a filter you can add to the power wire to eliminate electrical noise. Getting the antenna away from the engine is also suggested. AM radio frequencies are in the the band that most electrical noise comes from. FM is not which is why you don't have the problem on FM. When the radio is powered from the troller battery, the radio is grounded to it. The antenna is grounded to the hull of the boat which is grounded to the starting battery so that is an issue that would likely make the system subject to electrical noise. As for charging the troller battery from the engine -- that is futile effort since you would need to run wide open for hours to fully charge a deeply discharged deep cycle battery from a small outboard (or even a large one for that matter.)