Battery or Wiring?

[muskielaw]

I bought a used boat last year that came with a cheap lowrance (No gps) on the bow. I bought a new humminbird with GPS on the dash and when I ran both units at the same time I would lose the GPS signal on the humminbird. Turn lowrance on bow off and signal would come back. It wasn't a big deal last year because I rarely used the lowrance. Well I just bought a new humminbird for the bow and interlinked it with the one on dash and am having the same problem with some new ones. When I have both units on I lose GPS signal on both but if I have just bow on get GPS and just dash unit on get GPS. In addition, when I run the bow trolling motor it is shutting the bow unit down completely. It will turn back on but and if I have auto pilot on the unit will remain on but as soon as I increase the speed of the trolling motor bow unit shuts down. Running trolling motor has no affect on dash unit. So where should I start to find the problem? A few addional facts:

1) All electronics are hooked up to fuse box (under counsel) that goes to starter battery.

2) GPS is mounted on gunnal along side steering counsel and power goes to fuse box.

3) Trolling motor is hooked up to its own batteries, however, the wiring runs along the same side of boat as wiring for bow unit and then goes under counsel to batteries stored in the floor in the middle of boat next to steering counsel.

Any ideas would be greatly appreciated. Thanks

Muskielaw.

[upnorth]

If you can, try hooking up a volt meter to the battery when you have everything hooked up. It could be that you aren't putting out enough power to run it all at the same time. On occasion my graph will die when I fire up the pump for the livewell.

[Cliff Wagenbach]

I would not use the dash fuses. Run separate wires for the depth finders to the starting battery, (with an in-line fuse on each).

If the starting battery is in good shape you should not have any more problems. Usually a poor battery will drop your voltage below 12 volts when being used, which in turn will shut down most GPS/depth finders!

Cliff

[muskielaw]

I would not use the dash fuses. Run separate wires for the depth finders to the starting battery, (with an in-line fuse on each).

If the starting battery is in good shape you should not have any more problems. Usually a poor battery will drop your voltage below 12 volts when being used, which in turn will shut down most GPS/depth finders!

Cliff

Well I brought the battery in to the auto parts store and had it tested. They said it was like a brand new batter. I assume the test it under load? In any event, I will try hooking the depth finders straight to the battery and see if that helps. Is it possible that the trolling motor wiring would be causing this or is that only an issue with transducer interference? Thanks for the help guys.

[Cliff Wagenbach]

I do not see how the trolling motor would be giving you interference problems if you have your depth finder hooked to a separate battery, unless your trolling motor has some type of short in it. ???

If your transducers are mounted to close together that could give you problems.

Cliff

[muskielaw]

Wired the graphs directly to the starting battery and no more GPS problems!! The Volatage on the units went from 8.5-11 up to 12-13 with everything runnning. Thanks for the help!!