Trolling Motor vs Sonar - Battery Question

[WhitESOX]

Hi all, I got a deal on a Lowrance HDS-9 Gen 2 touch at BPR, as they are discontinuing it. This unit will work very nicely with the 12v Motorguide Xi5 which I also scored a pretty sweet deal on, especially with the tanking dollar. Will be installing this setup in time for the ice melt.

Wired a pair of group 27 batteries in parallel as I saved up for the troller - last year just used this overkill bank as house (livewell, bilge, radio, old Lowrance X4, lights, etc). A third (group 24) battery is separate and dedicated to starting the engine.

Apparently wiring electronics up to the same battery as trolling motor is a no-no (and says so in the xi5 manual), but I read elsewhere that wiring it to the cranking battery can cause feedback / interference - perhaps by the alternator charging it. Since the structure scan is a feature I'll want to use while engine is running - it apparently works at up to 30km/h, this could be a problem. Getting a 4th battery not really an option, nowhere to put and I'd be pushing limits with three grown dudes in the boat.

Does anyone have experience with this?

[lape0019]

Granted, it's not structure an or even an HDS unit but I've had my Lowrance elite 5 on the boat wired to my cranking battery for years and have had no interference with the big motor running.

You generally will get more interference with a finder hooked to the TM batteries.

Personally, I run everything off the cranking battery with the exception to the TM. The TM is the only
Item on deep cycles.

[toobinator]

You'll get much more interference off your trolling motor than you will your gas motor. Wire it to your cranking motor. If you fish a lot with your electronics and livewell pumps on and the big motor off, it might be wise to invest in a 27 or 29 series cranking battery, or, failing that, a set of booster cables.

Ed

[StarTzar]

You'll get much more interference off your trolling motor than you will your gas motor. Wire it to your cranking motor. If you fish a lot with your electronics livewell pumps on and the big motor off, it might be wise to invest in a 27 or 29 series cranking battery, or, failing that, a set of booster cables.

Ed

A set of booster cables is a must have.

[Lunker Larry]

You'll get much more interference off your trolling motor than you will your gas motor. Wire it to your cranking motor. If you fish a lot with your electronics livewell pumps on and the big motor off, it might be wise to invest in a 27 or 29 series cranking battery, or, failing that, a set of booster cables.

Ed

A set of booster cables is a must have.

And make sure they're long enough.

[scarkner]

You can use a good quality car stereo filter on the sonar, then you can hook it to either battery.

For example, search for "12 amp pyramid noise suppressor" on Amazon.

[WhitESOX]

I appreciate the responses, thanks. Should have mentioned we wired up a A - B - A+B switch between the batteries to act as that booster if/when ever needed. Occurred to me since the ground is shared between the two, perhaps I wire up another switch on the hot lead to the HDS, to alternate between the trolling bank and cranking battery (as I'll never use both the outboard and troller at the same time) selecting opposite power source. Have to take apart most of the boat anyway so this isn't much extra work.

It would result in an experiment of sorts - seeing if there actually is a poorer signal if powered from the cranking batt while powered from it. Will post the results in - hopefully - May!

Thanks again.
Al

[WhitESOX]

Have another wee issue planning this thing: Want to utilize existing fish finder as backup / other location on boat, but can't place another xducer of the same frequency on the transom due to interference. Found this thing which is a start (but gakkkk! at the price for a few ounces of wire). Can't seem to find a switch to do the opposite (switch 1 xducer between 2 units). The Xi5 comes with a built in sonar which connects to the HDS but obviously this can't be used at speed when the troller is parked up, and hopefully the length of the boat will avoid the problems with interference.

I would imagine a few folks on the board here have multiple sonar units on their rigs - how is that overcome, and does such a switch exist?

Thanks!
Al

[toobinator]

Al: I think I have a transducer switch at the store. I will have to root a bit for it though as it was one of my mistakes from a few years ago. If I find it I'll sell it cheap.

Ed

[WhitESOX]

Super, Ed. Thanks. That would be worth the drive to Winchester.

[jjcanoe]

I have the same setup, all is wired to the crank battery, only my trolling motor is wired to the deep cycles, never had a problem with interference off the crank battery. This is over 2 different boats and 4 different fish finders, some basic finders and recently fish finders with down scan and gps

[toobinator]

Found the switch. It's for switching between 2 tranducers into 1 head.

Sorry.

Ed