Depthfinder Issues

[montanagriz]

Hey Guys - I have a couple quick depthfinder questions I'm hoping you can help me troubleshoot.

1) I have a FishMark 480 mounted up front by the trolling motor that is running off my trolling motor batteries. Everytime I run the trolling motor I get bad interference which makes it tough to see anything on the unit. Right now I have a skimmer transducer mounted to the bottom of the trolling motor, but am replacing it this week with the "puck" style transducer designed for trolling motors. I'm hoping that may help some, but am I better off running the unit off a different battery than the trolling motor? I don't have a ton of space for another big battery, so would using a smaller Vexilar-type battery be effective?

2) My main depthfinder is an LMS-332c that runs off my starting battery. When I have the depthfinder on, and go to start up my big motor, I instantly lose power to the 332c the second I turn the key. It's annoying cause I have to turn the unit back on, scroll to the screen view I was using previously, and zoom-in again on the structure I was looking at on the Lakemaster software. This wasn't happening the first few months I had the boat, so I'm wondering if it's time for a new battery, maybe a deep cycle instead of a starting battery?

Any suggestions you guys have are appreciated. Thanks for your help!

[rmrakt]

Your noise is from the trolling motor. Depth Finders need to be wired directly to the positive terminal (best to have separate battery) to avoid interfence from trolling motors, etc. Always install an in line fuse as well. I run my front and back finders on my starting battery.

A weak battery will drop below the depthfinder's preferred running voltage and will cut out when you try to start your engine.

[Dahitman44]

Look at some of my other posts. I have had troubles of my own -- one thing I am sure of is you should not run a depth finder off of batteries from a trolling motor.

Good luck

[PerchJerker]

You have battery issues.

Save your money on the puck transducer, the skimmer transducer is fine on your trolling motor.

Wire your FM 480 to your starting battery, use 12 gauge wire for a longer run, and use an in-line fuse holder. That should cure the noise problem.

As the other poster stated, your starting battery is low on volts and that's what's making your 332 shut off. Take the battery to a battery or auto parts store to get it load tested, but chances are it's weak. Replace it with one with the most cc amps you can afford / fit in the boat.

[CrappiesNeyes]

I had the same exact problem that you are having. It turned out that my starting battery was on it's last leg. I replaced it with a new one and I have had no problems since. I am 95% sure this is also your problem.

Good Luck

[zachp]

I use a vexilar type battery for my trolling motor battery(334c), it lasts all day and since it's wired into it's own battery i have no noise issues, I do carry a spare with just in case.

Are you talking about using a deep cycle battery for your starting battery? If so I would advise you not to do that, get a new starting battery and your problem with the 332 will be solved.

[Hookmaster]

I use a Vexilar type battery for my Fishmark 480. It is 12 years old and still lasts all day. No interference at all. The graph is mounted in my old Clearwater Classic Ice setup so I can move it around a little in the bow so it is always where I want it.