Fishfinder wiring question...

Discussion in 'Boats and Motors' started by Salmonid, Sep 23, 2008.

  1. Ok folks, here is the problem, when i get to river spot and turn off motor, all is fine, fishfinder stays on but when i restart the motor, the power kicks off and I have to reset it every time, its really annoying. Now if I leave the key turned 90% off but not all the way off, it seems to wok out ok and stay on when i restart the engine. My question is this, is this ok? or am I realy gonna run down more juice by doing this? or shoud I just wire the Fishfinder to one of the non cranking batteries, I assume that when It starts, its pulling enough power to kick it off and the fish finder screen also seems to blink / change brightness wththe RPMs of the motor at idle speed.

    I do some drifting and its really annoying everytime I start up to have to wait 1 minute or so for the GPS to reset to actually track my course.

    Any ideas here on the best way to fix this problem?

  2. If you have a "house" battery available that's what I would recommend. That's how my boat is wired-all electronics are seperate from the starting battery. Sounds like your cranking battery is a little weak and the voltage drop that occurs when the starter engages is causing the FF to turn off.


  3. UFM82

    UFM82 The one others want to be

    The FF is set to shut off during low-voltage conditions. This protects the circuitry in the FF and prevents damage to the components. If your voltage is dropping below the minimum voltage required by the FF, I'd seriously look at load testing your battery or checking the amperage draw of the engine. Batteries in good condition shouldn't drop below 11 volts while cranking. If you have a weak battery it can go down to 10 or even 9 volts, still crank the engine but drop out the electronics. A starter motor can draw 100 amps on a boat engine depending on the size of the engine. If you have a weak cell in the battery and are only pushing 11 volts to start with, the engine may crank but your voltage will dip too low for the finder.
    You see the display flickering because your battery is not back to 12 volts right away and the engine is charging the battery. Smaller outboards have basic charging systems and aren't "clean" as far as power goes so your seeing those fluctuations in the screen. I'd make sure all connections in the harness are clean- battery terminals, connections on the engine itself and even the engine harness. Any dirty connections will increase resistance and increase your amp draw when cranking. Have you ever had a car that cranked slow and the lights turned off when you tried to crank it? Same thing- dirty cables.
    My radio in my boat would turn off when cranking the engine back in the beginning of the year. I'd crank the engine and POOF, the radio would turn off and I'd have to turn it back on and reset the stations afterwards. I found that the battery had a weak cell and resting voltage when fully charged was only 12.1 volts. A load test showed it dropping to 10.3 when cranking. I replaced the battery with a new Grp27 starting battery and the issue went away. That battery reads 12.8 volts at rest and only drops to 12.1 when loaded.
    Depending on your model finder, you may be able to bring up a screen that shows various readings and one of them may be system voltage. My X91 will show me system voltage on one of the screens and you may be able to find the similar screen somewhere in your menu. Check your manual to see if you can find that info.

  4. Thanks guys, Good info U-82! We should cross paths soon on the Ohio, look for the 17 ft Fisher with custom alluminum rod rack across the back!

    I think Ill switch to a "extra" battery I have on the boat. I have the Eagle 502c FF and I know the Lowrance version has the voltage but last time I looked, I didnt see it, doesnt mean its not there though, Im still learning all about it.

  5. you know i never thought of that when we wired that thing up. all you need to do is find a "hot" wire under there that goes to your other battery and not wired to the cranking battery. move the wire there and it will be fine.
  6. Salmonid...when you have your battery fully charged, it should read around 13.4V. If it can't reach that level, it might be time to replace. You can also determine its strength by having it load tested at OReilly or Autozone. A weak battery will almost always cause the problem you've had (if you have verified your connections are not bad).