wiring GPS, sonar etc.

[fishhuntadventure]

I am looking for some input here on how various guys wire up their electronics. I recently had another failure of a color GPS unit; it was suggested to me by an associate of the manufacturer that the GPS and sonar needs to be wired to their own exclusive battery. This made me question some conventions I learned years ago, but I am not settled on changing my setup just yet.

First, let me relate how I am set up now. I have two batteries; a group 27 trolling/cranking battery and a group 29 deep cycle. The 29 runs my 50# Minn Kota. The 27 is my starting battery and is wired up to run everything on board: Mark 5x Pro sonar, stereo, power port for my VHF, socket for cell phone, Elite 5 combo unit, lights, bilge pump. The two batteries are wired through an A/B/Both battery switch just in case I ever 'need' the 29 for a starting battery but that is redundant because my Suzuki 40 pull starts so easily and readily. I have a master disconnect switch which kills everything wired to the terminal block behind it. The bilge pump is not on this circuit but is wired to its own harness and switch. All the other accessories are powered through the terminal block with fuses in the circuit. I have a second redundant "ground" (negative) wire installed which connects to the battery and motor negative leads for the purpose of bonding everything through a path that is not connected to the negative terminal block under the dash. Probably not needed in a 'glass boat but a friend who is an electrical engineer assured me that it wouldn't harm anything and 'could' eliminate non-preferred galvanic fields from existing. Downrigger to battery ground natural voltage is in the 036-ish range everytime it's checked.

The person I spoke with suggested that I needed to remove the GPS and sonar from the starting battery and connect it to its own battery. Not being particular enamored with the idea of having a 3rd battery on board my 14' boat and having 25 years + of exposure to marine and low-voltage wiring conventions I am not convinced this is necessary. I started with sonar on board in 1992-ish with an Eagle Supra Pro ID wired to the starting battery- the only battery aboard- and have never experienced any issues with electronic noise other than some spark noise on the VHF at near WOT. All my power wiring is done with heavy-gauge copper wire, connections are mostly soldered to lugs etc. I have no problems with performance of the GPS unit, but I am on the third unit to have the screen 'die' in 5 years.

Even while trolling with the gas motor my voltage seldom goes below 12.4 as my 40HP has an 8 amp charging capacity which seems to trickle just enough while trolling to keep everything happy, and usually running for a few miles back to the launch after fishing brings it up to 12.8 to 13.2 volts. I just don't understand how my alternator charging the battery would make the GPS display die an early death. That logic would mean that folks who use GPS units on snowmobiles, in cars, out west off road in Jeeps and such would not be able to run their units on their accessory circuits in their vehicles, right? But people do- even in the Baja 1000 I have seen dual GPS units (without the sonar) running in in-car photos of racers. I seriously doubt they are running the units off batteries not connected to the charging system.

This just doesn't make sense to me since bass boats come pre-rigged on the charging system with the exception of the electric trolling motor batteries- all accessories are on the charged circuit. Further, all my other electronics including my sonar(s) are wired the same way and even my 1992 Supra Pro ID still works- and fine. I have had to replace transducers, but never had the head unit die.

Now that my long winded diatribe is over here are the questions:
1] Do you run your electronics off a battery connected to your boat motor's charging system?
2] or, Do you run your electronics off a separate battery?

Thank you for your input-

Mark

[Wallyandre (Andre)]

You're set-up is perfect

[Gecha (Gerry)]

Mark, I have 2 group 29 batteries connected with an A/B Both switch, but I am only using one battery at the time.
All my electronics and downriggers are running on the same battery.
On my 12 year old pontoon boat, I am running everything from a group 24 battery and still running the same 9 year old Lowrance GPS/fish finder.
Your configuration looks good.

I don't think a low voltage should do anything bad, as these new GPS/fish finders tend to shut off when voltage drops too low.
Could it be you may have some temporary peaks that might send too much voltage to the module?

[fishhuntadventure]

Thanks guys. I still can't see why stuff would need to be separate with everything running properly and according to conventions.

digitrol? Thoughts?

[fishingmachine]

whatever the problem is,it is not the wiring,what GPS brand is it?

[VTgooseman]

Been running my Humminbird units off a similar set up without a glitch. Two batteries 27 series to a Perko switch.

[digitroll (ron)]

Everything I run is off a single 1000 marine cranking amp starting Interstate battery charged by a 60 amp charger on the 150 hp engine while trolling or running on plane. I don't have any deep cycle batteries. Or second backup battery. Just a lightweight jump pack battery (purchased at Wallmart) for an emergency for which I have never had to use in 8 seasons of running a single battery.

I don't have an electric trolling motor that would require deep cycle batteries.

Keep it simple. I always check my voltage level on my Smart Craft RPM gauge the night before (12.3-12.5 volts it should read) an outing so there is no surprise at the launch. Also the master power switch is turned off at the end of the my trips. Like trailer tires (every 5 years) I replace the battery every 4 years. I don't wait for cracks in tires (tire failure on the road) or batteries to go dead randomly.

"No one plans to fail they just fail to plan"

[Reel Delight (Walt)]

I have a dual battery set-up. One battery takes care of the main engine,house electrical such as lights,accessories , VHF radio, sound system , bilge pump and my main GPS/ sonar unit. The second battery takes care of my kicker motor, downriggers, wash down system and a second fish finder unit.? Both batteries are wired separately to a battery shut-off witch and treated as separate electrical systems; but they can also be connected together through switches inthe case of an emergency or a no start condition of either battery.

I have no problems losing displays except for a couple of past years with a previous boat and when I was using Lowerance GPS units. It was not a electrical system problem back then ;but it was problem that Lowerance had with their chips over heating.

As others already stated...your wiring is okay. Yet I do suggest that you might want to shutdown your GPS prior to starting your 40hp outboard to prevent a voltage drop to the GPS unit and then turn on the GPS once the engine is running.