We have had issues with some high current carrying cables causing EMI with a sounder, like when the autopilot motor was engaging/windlass/electric reels, etc. We've usually be able to minimize it by rerouting the transducer cable in most cases. Is this your house bank or engine bank? To be totally honest I've never had situation with the transducer up against battery itself, so the these suggestions are really just conjecture.
Not really worried about the transducer as much as I would be concerned about the xducer cable. Even though they're shielded, if we're talking a heavy enough current, there could still be problems. If it's possible to route and run the X-Ducer cable up and away from the battery cables, do not run them parallel , maybe clamp on a few ferrites to the cable, you might be able to mitigate the radiated EMI from the battery cables/terminals.
A good litmus test before installing it would be to place the transducer in bucket of water in the bilge right next to the battery, leaving plenty of slack XDucer cable nearby as well, then connect it to the sounder and start turning on loads one by one to see what kind of noise is produced on the display. Even though the screen won't show anything resembling a water column considering you're in 6 inches of water, you should still notice what is usually vertical specks of noise across the entire display. If you do end up getting noise, start collecting the slack cable near the battery and heavy cables, get it away it away from the source. See if that changes things. If not, then it may just be that the transducer isn't going to fly in that spot. Best of luck, wish I could provide better input, but like i said this one's new. Curious to see how it goes.
Thanks Chris. The battery is just a starting group 27 for the generator. It just works out as a good place to put it. I'm going to go ahead and put it together as planned, if there's an issue once launched (new build) I can relocate things. Thanks again for your input, I'll update this in the spring.
Interference can be reduced by wrapping the cable with foil-backed tape, or just wadding tinfoil around it.
This has worked for me where all the wires had to run together in a duct to the upper helm.
As mentioned above, autopilots are usually the worst item on the boat for interference.
I haven't tried it yet, but thought about wrapping the autopilot wires to isolate them as well.
BTW, if you are serious about sounder use, put the ducer in the water. Shooting through the hull is like having fogged up sunglasses.