Any inputs are welcome ?

Some things to look at:
How did you mount the Xi5 and the HDS (how much of them?),
did they have (maybe unwanted, unrecognozed) common ground? (- from HDs to -from one of the the Xi5 Batts.)
ALU Boot? Maybe common ground over the Transducer, hull of the boot to the Xi5?
See what happens after unplug the NEMA Cable from the HDS.
Try to disconnect one plug at the time to see if you could find the transmission way of the interference.
How does the interference look like?
Sparkles at the screen or white areas, or?
Does it relate to the rpm of the XI5?
More or less if the rpm increase?

... a bit more informations about, so maybe the Pro's here can help you..... :-)

NMEA connections are very specific. make sure ALL your Devices (Xi5, power, and head unit) are plugged into the TOP of the T connectors
the straight connectors are only to connect T's together and terminators.

send a screen shot of what you call "Interference". is our Xi5 saltwater or freshwater with a transducer built in?

running 2 transducers at the same frequency will cause interference in the water as each transducer picks up the others echos
happens to me when another boat gets too close

The Interference shows as solid blue vertical bars.

The NMEA set look like this.


placed in a flight case with the battery and the units mounted on top.


And the motor is mounted on a removable bracket to mount it on different boats.

Wil try to connect the NMEA network like fonso2616s drawing and hopefully try it out tommorow

Please make a Screenshot/Screencopy of the interference.

I find it hard to belive that intereference would follow the NMEA-cable as long as it has a good ground. But that small battery might not be enough of solid ground. So just to eliminate that, I would try with a larger battery and rewire the ground as well. The solid vertical lines tou are seeing are from the variations in power when the TM draws power, and unless the TM itself does not have solid ground, those variations are a sign the rest of your system ends up as grounding for the TM.

I use the same setup, just on a larger scale, with no intereference. Two 100A AGMs for the TM and 63-126A for my HDS-units.

So how do i create a proper ground connection ? the problem is that i have to mount everything and take i of when i go out, so that's why its in a case and on the mount.

Picture of interference, i got even worse after i mounted the NMEA network the other way.

This is a rather extreme solution: gifflar.blogspot.no/2014/11/hur-man-far-...gar-pa-ekolodet.html

Start by going over your wiring between the TM and its battery. In a system like this, the battery is ground. But with extreme top-outs in voltage sometimes that ground is not enough and since electricity simply follows the path of least resitance you might end up with something other then your battery acting as a ground. This is a bad spot to be in, as you are seeing on your screen. It can also be quite dangerous (if one charged the batteries in the boat) and cause corrosion, so you really want to get rid of this. If rewiring the TM to its battery does not help, contact the agent for the TM (Thermoprodukter) as well. There might be something wrong with the wiring inside the TM, leading current somewhere else then battery-ground.

Thanks for the informaiton ill try that, when i get the time. :D

Is there a way to make the ground connection on the HDS better as well?

The amp-draw in your HDS is very small, depending on model but under 2Ah. Xi5 is in the 50-60A neighborhood at max. But to answer your question, no not that I know of apart from the usual stuff (better connections, thicker wires, larger battery).

How long is the wiring between your TM and its battery, and what size cable are you using?

Use about 3 meters og awg 5 (16mm^2), and then Connection to the TM with Anderson plugs, and everything is soldered on properly.
I could trim the cables down to something like 1-1½ meters,