Voltage drop seems excessive

[icefisherman]

Great and very informative post Dan.

Appreciate the time you've put into it as I am sure it'll be good reading for many on the board.

We'll be doing more testing with Brian using your instructions in the next few days to see what it'll add to what we already know.

 

Using the original Lawrance wires/fuses/fuse holders etc.

520, 525 and the GPS antenna all come with the black rectangular rubber waterproof fuse holder with blade style fuses inside.

 

Cheers,

Ice Fisherman

[SlowPoke]

Thanks to Dan's VDT (voltage drop test) post we can narrow down the problem. To further diagnose it means removing interior panels to test harness plugs. We tried cleaning the fuse and fuse holder connections with no change. VDT testing tells us there is more than one issue with a .05v drop through the fuse block and an additional .13v drop between the block and switch. By Dan's description drops of that value are acceptable across a circuit but the combined loss .35v is unacceptable.

 

Battery Terminals 12.58

Battery Connected 12.58

Fuse input 12.57

 

VDT via Boat harness

VDT Batt to Fuse input -.17

VDT Batt to Fuse output -.22

VDT Batt to switch input -.35

 

VDT via jumper wire from battery to switch input

VDT Batt to switch input -.17

 

So, now we have the switch connected to battery 2 and showing normal readings and not taxing the main/starting battery. We'll save destructive testing for a later date!

[vinnimon]

You mean NON DESTRUCTIVE TESTING! Right?

What is the voltage reading at the plug(s)with it disconected? On the dash their was onother plug! Are they tied into each other?

Edited October 30, 2010 by vinnimon

[SlowPoke]

You mean NON DESTRUCTIVE TESTING! Right?

What is the voltage reading at the plug(s)with it disconected? On the dash their was onother plug! Are they tied into each other?

 

You haven't seen me work LOL

By destructive I meant taking the boat apart.

They are running off the same circuit. Voltage when disconnected is okay but nose dives when they are powered up. Everything is okay when connected direct to the battery so that eliminates the possibility Lowrance connectivity issues.

[DanD]

Would fishing a new wire not be easier then actually finding the corroded section?

I guess that would depend on what else is running on that circuit eh?

But if its just the graph; kill that wire at the source and run a new wire.

 

Dan.

[Fisherman]

There's corrosion in them there wires and connectors, rip it out and rebuild..soldered connectors with liquid tape and non of those open to air and corrosion crimp connectors. Quit wasting time, there's fish to be caught.

[Tybo]

Time to do a amperage draw test. Set meter up to do amps. Look in the manual it will

tell you how much amps the unit draws.Put test leads in fuse holder. turn unit on .if amps are to high it's the unit.to low it's your wires.

Like I always say. IT'S NOT ABOUT THE VOLTAGE BUT THE AMPERAGE.

[SlowPoke]

Would fishing a new wire not be easier then actually finding the corroded section?

I guess that would depend on what else is running on that circuit eh?

But if its just the graph; kill that wire at the source and run a new wire.

 

Dan.

 

It's just the graphs on that circuit and we've avoided it by powering the switch from battery 2. The downside of this is battery 2 also powers his bow mount trolling motor but he only uses that once or twice a year. Battery 2 is being charged when the kicker motor is running.

 

There's corrosion in them there wires and connectors, rip it out and rebuild..soldered connectors with liquid tape and non of those open to air and corrosion crimp connectors. Quit wasting time, there's fish to be caught.

 

I still haven't seen the mess in person; I don't know if its a tough job or a breaze. I do think we should VDT the other circuits to find out if this is an isolated issue -or- a tow call waiting to happen.

[Fisherman]

I took a quick look, each unit only draws 3 amps max, therefore I doubt it's actually a wire rating issue unless he's used something thin like 24 awg for a looong run. I've seen some of that spagetti wiring in some boats (and other vehicles), some people should not be allowed to play with their wires.