Correct Dual Battery Switch setup

[sam am I]

P.S. Silver spotted that/those diodes (good eye silver!) hang'n off the back of that switch, Is perhaps that (remaining) diode dropping voltage and is somehow re-wired and is now inline with the boats voltage gauge?.........Hmmm? And where does that other fried wire go? What was it for? Are your Anchr/Nav light working okay?

 

[foilled]

P.S. Silver spotted that/those diodes (good eye silver!) hang'n off the back of that switch, Is perhaps that (remaining) diode dropping voltage and is somehow re-wired and is now inline with the boats voltage gauge?.........Hmmm? And where does that other fried wire go? What was it for? Are your Anchr/Nav light working okay?

There like 5 prongs on the back of the nav switch. There’s ones prong empty with the the burnt diode and there’s another prong with a wire going in and another diode going directly to another prong on nav switch with the other end of the burnt diode. The nav lights only works in one direction turns all red green and white lights on. The other direction in which only the white moorning light should come on, no light does at all.

 

[foilled]

In order to find the drop and given its consistently there and is around 1.2-1.5V volts with varying loads

A few other ways are possible but, none simpler than walking down the path and checking nodes..........

Above, you found the drop to be on the positive side of things, therefor........

1) Find and identify the main positive voltage feed from the battery to the helm, there's ONE main path with branches (your meter is/on a branch)

2) Turn on load/s that create the repeatable drop.

3) Go back to your positive side test you did above, one meter lead (pos) to the battery + and the other meter lead (neg) to the gauge +

4) Re-verify drop is occurring..you said you can get 1.2-1.5V.

5) Leaving the meter lead (pos) alone and remaining securely connected to the battery +,

6) With the OTHER meter lead (neg) that is on gauge +, start working (probing) your way backwards towards the battery down the main feed path you identified in #1 above backwards towards the battery probing points of interests (connection, junctions., slices and what have yous)

Example A

You probe (pierce the insulation with a needle) of the wire 2" down from where the gauge + point, you look at you meter and it still reads that 1.5V drop........

Explanation A......

This result seems logical because it only 2" from the gauge + connection and the wire looks normal and in good shape (not been hot, frayed, spliced etc etc)


Example B

You probe (pierce the insulation with a needle) of the wire 3' down the main path from the gauge + point, you look at you meter BUT now, the drop is GONE, it reads 0.03V.

Explanation B......

This is because as you moved the meter probe (neg) further from example A's probe point towards the battery along the main feed path, you jumped over THE ****ty connection.

Now, logically you know the problem (the voltage drop) HAS to be between example A and example B. Work your way FORWARDS toward example A looking for a suspect connection, splice, hot spot.

This is most likely how a mechanic would find the problem, no real other way and I really don't think I personally could make a better explanation of this process.

If this process is confusing, hard to follow and you can't seem to use this method of logically dividing and conquering, then perhaps the mechanic would be the better choice for you to get your problem (voltage drop) resolved.

If I turn I no accessories on how much of a volt drop should I expect from each alone? The nav lights. Bilge pump or lighting? How about all on together?

 

[foilled]

That's your side, start hunting....Should come down to around .03V like the neg is when you find your issue. Also, add that drop (1.2-1.5) to all your past meter readings........Make sense now?

Reading back on this what’s your opinion of my voltage drop is a higher number at gauge then the number from battery positive to gauge positive. Ex. I’m down to on .3 to .4 volt dropage from battery postivr to gauge positive. While the gauge is reading over 1 volts shorter then the volts tested directly off battery?

 

[Silvertip]

The "amount" of voltage drop along a circuit depends on lots of things. 1) state of battery charge 2) battery condition (ability to hold a charge), 3) number of connections and splices in the circuit, 4) condition of splices and connections (corrosion), 5) current draw of the device(s) in the circuit 6) the wire gauge used in the circuit and 7) the accuracy of the meters and gauges. Cheap meters provide inaccurate readings. Boat gauges are notoriously inaccurate (at least for the purpose you are attempting to use it).