Wire guage for running sounders?

[Camhawk88]

I have hooked up an LCX27c through a LBS-1 but am not getting a decent showing.
If I hook the transducer direct to the sounder I get a fairly patchy showing and often it will have a few seconds pause and break ups of the display. If the transducer goes through the LBS-1 unit I get nothing.
The LBS-1 is powering up and the ethernet is working- green network light flashes but the info is not coming through. I have the sonar setting correct so it is running through the LBS-1.

For the wiring I have the sounder, LBS1 (red and yellow wire), GPS and NMEA2000 back bone positive wires all running to a 4mm wire which connects to the positive bus. On the negative side I have them all hooked into the bus via a 2.5 mm wire. The wires run about a meter to the buses.
I figure I may need to upgrade the negative wire to 4mm. Is this the likely cause of my problem? I feel that the sounder is not getting enough voltage.
ANy help would be appreciated.

Cheers,

[patrol50]

mate no expert but my understanding is that the smaller 2.5 mm neg wire controls even if you have 4 mm on the + ve side ( in fact the 4 mm is now acting pretty much a 2.5 mm wire or similar ) - i would upgrade the neg wire to 4 mm if it was me

cheer rob

[Owen]

Very unlikely a 1m run of 2.5mm2 cable is causing any significant voltage drop, so upping that section to 4mm2 will make little difference..
You need to calculate total load over entire circuit to battery and back (i.e. add both +ve & -ve)

This may help.
http://www.calculator.net/voltage-drop-calculator.html

[patrol50]

Very unlikely a 1m run of 2.5mm2 cable is causing any significant voltage drop, so upping that section to 4mm2 will make little difference..
You need to calculate total load over entire circuit to battery and back (i.e. add both +ve & -ve)

This may help.
http://www.calculator.net/voltage-drop-calculator.html

probably quite right but a process of elimination is always good - and the run is actually 2 m (approx 1m of each each way both acting as about 2.5 mm wire ) and if its not the wiring size then any other likely or helpful suggestion such as a loose crimp, dirty contact point, etc ??
cheers rob

[Owen]

probably quite right but a process of elimination is always good - and the run is actually 2 m (approx 1m of each each way both acting as about 2.5 mm wire ) and if its not the wiring size then any other likely or helpful suggestion such as a loose crimp, dirty contact point, etc ??
cheers rob

All of the above may apply as could the size and condition of the wire from battery to bus bars.
If the copper isn't nice and shiny (should be tinned) then it's probably degraded and will cause voltage drop and/or reduced current capacity.
Cut your lugs off and strip some wire to check would be my suggestion.


Cheers
Owen


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[Camhawk88]

All new wiring and the bus bar connections are good.
Will replace the negative main wire and see how it goes when I next get out.
As a point of interest I turned the ethernet wire around between LMS and sounder and on dry land it seems to have made an improvement- wont know until it goes in the water again but.

[patrol50]

All new wiring and the bus bar connections are good.
Will replace the negative main wire and see how it goes when I next get out.
As a point of interest I turned the ethernet wire around between LMS and sounder and on dry land it seems to have made an improvement- wont know until it goes in the water again but.

think its possible to kink the ethernet wire and they dont like that so that could be your prob - still would upgrade the neg wire though - ethernet needs to be a nice smooth curve if needs to curve around something - i have run mine thru a meter and a half of 32 mm gently curved poly around the bow of the boat to get it from one side to the other to hook up a lcx27c to hds 7 so as to avoid any chance of a kink
cheers rob

[Camhawk88]

Pulled my finger out and replaced the neg wire with 4mm. Did the trick nicely.

[Fed]

Replacing the cable wouldn't have fixed it you must have inadvertently fixed a bad connection or something else.

[patrol50]

Pulled my finger out and replaced the neg wire with 4mm. Did the trick nicely.


way to go and glad the swap to 4 mm has done the trick - another good reason to use 4 mm is that its much easier to get a better crimp with it than with 2.5 as not much copper wire thickness in 2.5 ( i avoid 2.5 wire if possible) - but some expert will disagree of course !!!

[Camhawk88]

Yeah I cant see how there were any poor connections with what was there. The terminal was crimped and soldered. The other end was soldered to the other wires in a junction. The same was done with the 4mm wire- simple cut the 2.5mm at the junction, wrapped the 4mm around it and soldered. Terminal afixed the same as previous.

Not saying it was impossible but I dont see where the bad connection could have been. If I was really curious I guess I could put on the 2.5mm wire again and see if it works but Im not curious enough to mess with something that is now working. But I know in theory that with the amount of current draw that 2.5mm wire should have been sufficient.