Fish finder turns off when boat engine turned on

[Lively1]

I've noticed that my fishfinder will often turn off when i start my boat engine after sitting and jigging for a while. is that normal? can it hurt the finder somehow? not sure how it's wired, I just used the same leads that the original was connected to when i installed the upgrade.

[Roughrider IV]

Battery getting weak.

[Dick]

I have a new low cranking amp marine battery and after trolling a while the voltage drops.

my finder will warn me. when i start the motor, the finder will shut off due to not enough power.

I need a bigger deep cycle battery.

[ray koziatek]

yup agree battery

[Sk8man]

Deep cycle batteries for the most part aren't designed as starting batteries. I have one that is designed for both but I use it only as the battery for my downriggers (and as a "backup" starting battery)and have a high amperage starting battery for the main motor.  Standard deep cycle  batteries are designed to run things that are drawing amperage over time rather than things like high draw initial start ups of big motors.

Edited August 31, 2014 by Sk8man

[jimski2]

For safety of your fishfinder and the ability to start your engine the fishfinder shuts off automatically when the available voltage falls to about ten volts. Many boats do not have a battery charger that maintains the battery at peak voltage when the boat is stored but the owners depend on the main engine charging system to maintain the battery. Running the bilge pump, night lights, radio transmissions, downriggers and rock and roll music will kill your battery especially when the engine is idling while trolling.

Edited August 31, 2014 by jimski2

[muskiedreams]

Lively1,

 

First of all, excuse me if I am teling you some details that you are already aware of.

 

If you have a separate starting battery and deep cycle battery for bowmount and or downriggers, it might be best to connect the fishfinder to the deep cycle battery.

 

What is happening is the voltage "at" the fishfinder is dropping below the threshold required to run it. There are several possible things that can be causing the problem. It can also be a combination of causes.

 

1) Weak battery. If it is not at full charge, or not able to hold a full charge due to age and/or internal fault, when you start the motor it will draw the voltage lower while starting.

 

2) Too many things running off the same battery while the motor is not running and/or the motor charging system may not have enough charging power to bring the battery to full charge during the time it is running.

 

3) If charging system of motor is not charging the battery when it is running.

 

4) Drop in voltage between the battery and the fish finder. This can be caused by poor (or corroded) connections between the battery and the fish finder. It can be fuse connections, battery connections, crimp connections of wires to terminals, switches and/or connectors. Inadequate wire size, possibly in combinations with length of wire and what other accessories are connected to the same wire.

 

I would check it out in the following order.

 

1) Make sure the battery is fully charged and the water level in all of the cells is full. If not, top off with distilled water. Then check the condition of all the cells with a hydrometer. They are inexpensive at an auto parts store. Moderate to poor indication on any of the cells indicates the battery should be replaced.

 

2) Measure the voltage on the battery with everything off and engine not running (it should be about12.5 to 13 volts). Then measure it with the motor running. It should be a volt or two higher, which will indicate that the motor charging system is working.

 

3) If no problems are found from 1 and 2 above, check and clean all connections between battery and fishfinder. Make sure all connections are tight. Clean metal surfaces with scotch brite pad, emery cloth, or sand paper. This includes fuse contacts. Shiny metal is clean. You can use contact cleaner or WD 40 for connectors you cannot manually clean. Any connectors that are questionable, should be replaced. When installing new connectors to wires, make sure the wire is not oxidized or dull looking.

 

Hope I was helpful. Good luck!!

[Lively1]

thanks everyone, this forum is such an excellent place for info on things like this. I haven't even looked at the engine starting battery since buying the boat earlier this year, just been too busy. I have a deep cycle trolling battery, but the only thing running on it is the trolling motor. I will get it all sorted out sooner or later.

[Sk8man]

Sounds as though the finder is hooked up to the starting battery and it needs charging if the boat hasn't been used frequently (or weak battery as noted above)

[Dick]

I should have said I need a 2nd battery a deep cycle.

[Skippers Trophy 01]

On our FF, we have the ability to display the voltage on the screen.  If yours has this ability, put it up and watch it.

[TyeeTanic]

Same with us, we display voltage on our FF.

 

If it drops below a number it cuts out.

[Has Been]

Mine has been doing the same thing for 20 years. I learned to turn the depthfinder on AFTER  I start the engine.

[High Bidder]

My Lowrance GPS turns off when I start my engine but my Humminbird unit doesn't. My Simrad auto pilot also isn't affected by the voltage drop when starting the engine. My batteries are new and fully charged. I do just like Has Been said, Turn on the unit after starting the engine.

[shadster]

 I turn the bilge pump on and the FF goes off. I think they are all connected to the same fuse box. I'm going to put it on its own battery if I can't figure it out.

[Xxx]

On August 31, 2014 at 9:15 AM, jimski2 said:

For safety of your fishfinder and the ability to start your engine the fishfinder shuts off automatically when the available voltage falls to about ten volts. Many boats do not have a battery charger that maintains the battery at peak voltage when the boat is stored but the owners depend on the main engine charging system to maintain the battery. Running the bilge pump, night lights, radio transmissions, downriggers and rock and roll music will kill your battery especially when the engine

 

What if I listen to country music instead of rock & roll will that make my finder stay on then?? gotta give me credit there right??? 

[Sk8man]

Mike I think Classical music is supposed to be easier on the battery

[jigstick]

Having two batteries on a boat is one of the most basic safety checks you can have in my opinion.  Very few things would suck more than not being able to start your motor because of a truly dead battery.  Installing a 2 battery setup and Perko switch is very easy.  Use a "starting battery" to turn over the motor, and a "deep cycle" to use while your engine is off.  Keep them isolated.  And always have power to start your engine.