Changing a portable Fish Finder to built in - Power?

Hello,

I am looking to semi-permanently install a portable fish finder into my boat. I have a Cuda 128 that takes 8 AA batteries. I am planing on supplying the unit with the trolling motor's battery. Is there a danger in using the marine battery? Could I fry my fish finder?

Is 12 volts just 12 volts or do I need to worry about the amps?

Thank you!

Craig

Re: Changing a portable Fish Finder to built in - Power?

cprince,

You should have no problem converting it to a permanent powered unit. I do this all the time with my Cuda 128 and Humminbird Piranhamax215 portable, just have a fuse inline (3 amp) to protect the unit for any voltage spikes.

Rob

Re: Changing a portable Fish Finder to built in - Power?

I had an issue with my old Eagle Fishmark 240 where it did not like the trolling motor being on the same battery. Gave too much noise on the screen while trolling.

I'm sure I could have isolated it somehow, but ended up just buying the D-Cells for the kit. One set lasted a season for me.

This was with a Motorguide 46 lb electric.

Re: Changing a portable Fish Finder to built in - Power?

Thanks for the replies!

I have a whole odd-ball/hillbilly/cheap Scotsman power distribution concept that I am putting in by the end of the week;

One 12 volt Battery ---> a normal household power bar. I bared the plug end and I am putting either alligator clips or those little washer looking joiners that get screwed down onto the battery post. I removed the 15amp breaker from the power bar, as I am told that the trolling motor will draw up to around 40amps.

To power all my 12 volt equipment I soldered together a couple of custom ends;

Trolling Motor - I ripped out the round ground off two three pronged plug u-grounds and soldered them to the end of another u-ground (I work in the hi-tech bizz and have access to an obscean ammount of u-grounds!). This fits perfectly into the trolling motor's feamale plug.

Fish Finder - I have made a wire with a couple of pillaged pins from an old printer cable that fit into the power plug part of the unit perfectly. I was able to get a flexible head to put on behind it on the wire providing a somewhat water resistant connection. On the other end I soldered a 3amp fuse (Thanks RobG!) in line on the black wire (- I think!). And to finnish this bastardization off, I soldered all this to a laptop power plug.

Power Inverter - Simple stuff here, all I have to do is cut the feamale end off a u-ground and screw the wires into the terminals on the inverter.

All of these plug into the raped power bar as you would with 110 appliances. I am going to stow the power bar in a locker with strips of rubberized mat protecting it from splashes.

I may be mad.

Re: Changing a portable Fish Finder to built in - Power?

Some concerns...

The plug strip is rated for 15 amps, not for 40. Feel the plug strip wires when the trolling motor is running at full throtle. They will get very hot. This is the equivalent of putting a penny in the fuse socket to stop it from blowing. By the way, the small wire in the plug strip will really drag down your trolling motor.

As far as the fish finder, add the fuse and it may work. As Tackle washer said, it may get some interference from the trolling motor. My trolling motor actually recommends running the fishfinder off the starting battery if this is a problem.

RobG said the fuse will protect against voltage spikes. That is incorrect, fuses will protect WIRE ONLY against overcurrent, not overvoltage spikes. This is a common mis-understanding.

TerryMSU

Re: Changing a portable Fish Finder to built in - Power?

Thanks for the helpful comments and the concerns you raised. I will double check, but I was careful to make sure that the wires that I am using are at least the same gauge as the wires coming from the trolling motor. As for the power strip, the interior of the thing is "wired" with metal rods. The wire from the power strip may be under gauge.... I will have to double check that one!

As for the penny analogy, I would more likely use a bullet to replace a fuse!

Re: Changing a portable Fish Finder to built in - Power?

terrymsu,

Sorry for the incorrect term for the fuse appication. The fuse is to protect the fish finder against over current not spikes. Most fishfinders I've installed can handle 16 volts with no problems.

Rob

Re: Changing a portable Fish Finder to built in - Power?

Whew...can we say Rube Goldberg. I too agree with terrymsu, the wiring of most plug strips is to accomodate AC wiring. Higher voltage, lower amperage draw. A DC system is opposite. Lower voltage, higher amperage. Those wires on that strip plug will heat up and you will affect everything plugged into it.

Seems as tho you are going to a bit of trouble here, with all the soldering, connectors, etc. One weak link and all that for nothing.

If nothing, cut up an extension cord with at least 14 ga wire and wire nut the whole mess together. Not the way I would do it but it would not create the overheated wire problem you will incur with what you have done. You can get a terminal strip with a common side for the grounds and have each red power wire come off seperate fused terminals.

Also, you should fuse the red wire going to your fishfinder, not the black wire.

Good luck!

Re: Changing a portable Fish Finder to built in - Power?

triumphrick said:

Whew...can we say Rube Goldberg. I too agree with terrymsu, the wiring of most plug strips is to accomodate AC wiring. Higher voltage, lower amperage draw. A DC system is opposite. Lower voltage, higher amperage. Those wires on that strip plug will heat up and you will affect everything plugged into it.

Seems as tho you are going to a bit of trouble here, with all the soldering, connectors, etc. One weak link and all that for nothing.

If nothing, cut up an extension cord with at least 14 ga wire and wire nut the whole mess together. Not the way I would do it but it would not create the overheated wire problem you will incur with what you have done. You can get a terminal strip with a common side for the grounds and have each red power wire come off seperate fused terminals.

Also, you should fuse the red wire going to your fishfinder, not the black wire.

Good luck!

Click to expand...

Thanks again for all the helpful concerns and suggestions. I suppose I will put this off a little for now. I will rethink my whole Hillbilly/cheap bastard setup.

From the trolling motor to the battery; would solid copper interior house wire be ok? Or is there too much impedance?

I am just thinking about what I have available to me without putting out any $.

I suppose I will just have all three units going directly to the battery and not use the power bar at all. I am still thinking about a simple power distribution system that I can make myself, just not sure how to go about it now. The whole thing that I am looking for is ease of connect and disconnect as my charger is not on board and I will have to remove the battery daily.

Hmmm....

Re: Changing a portable Fish Finder to built in - Power?

cprince said:

I will rethink my whole Hillbilly/cheap bastard setup.
From the trolling motor to the battery; would solid copper interior house wire be ok? Or is there too much impedance?

Click to expand...

Hey, watch it! I resemble that first remark (hillbilly)

You are probably talking about romex cable or just thhn copper wire. Sure, that would work just fine. And go to a big box (guess we cant say Ho..De... or Lo...) and in the electrical dept. you will find a myriad of male female disconnects, couplers. Find an appropriate one to attach to the pigtail power wire from the fish finder and hard wire the other two.

In over 40 years as an electronics technician, many problems encountered have been power related, and many of those problems have been connections. So just trying to help.