12 volt wiring help........please!

[ColinR]

Gauges on my boat started acting up so I do some investigating......tracing out power I'm only getting 6-7 volts at the fuse. Pull the fuse and at the fuse holder I have 12 volts. Put fuse back in and it drops back down to 6 volts. Thinking it's maybe a fuse problem I took one off my mule (tested it before I removed it, 12 volts on both sides) and get the same result when I put it in fuse holder on boat. I'm stumped. Could it be a grounding issue?


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[Marion]

So when you have the fuse in the holder you measure 12V on the battery side of the holder and when you put the fuse back in then you measure 6-7V on the fuse? If this is the case then it sounds to me like you either have something putting to much of a load on the battery or your battery is bad and it will measure 12V with no load but when you put a load on it the voltage drops. I'd bet that your battery is weak and won't hold 12V when a load is applied to it.

[Txnative78]

fuse holder is corroded and not getting a good conection to the fuse.

[Txnative78]

try bending the blades on the fuse so they will fit tighter in the holder.

[Txnative78]

Most boats the fuse that runs the gauges is on the engine, can you see for sure that that fuse is supplying power to the gauges?

[12RingKing]

sorry, I think my original prognosis was wrong

[ColinR]

fuse holder is corroded and not getting a good conection to the fuse.

try bending the blades on the fuse so they will fit tighter in the holder.

Most boats the fuse that runs the gauges is on the engine, can you see for sure that that fuse is supplying power to the gauges?

The fuse holder is not corroded, the fuse fits tight kinda snaps into place. The main fuse on the motor is good. Motor starts fine has plenty of juice for cranking.

[ColinR]

So when you have the fuse in the holder you measure 12V on the battery side of the holder and when you put the fuse back in then you measure 6-7V on the fuse? If this is the case then it sounds to me like you either have something putting to much of a load on the battery or your battery is bad and it will measure 12V with no load but when you put a load on it the voltage drops. I'd bet that your battery is weak and won't hold 12V when a load is applied to it.

When the fuse is not in the holder I read 12v on the power supply side, obviously 0v on the equipment side. When I put the fuse in the holder I read 6 volts on both sides. And the wires get hot. I'm thinking you might be right on something putting too much load on this circuit. Batteries are good as all other electronics work fine and motor starts just fine.

[DRT]

fuse holder is corroded and not getting a good conection to the fuse.

DC circuits have oxidation issues.

[ColinR]

Boy these boats nowa days are way too complicated. I think I have traced the issue to the NMEA network. Had to google it to figure out that is is. Lol That is where the gauges get there power and it's the power supply to this network that I'm not able to maintain 12 volts. Now to try to figure out what the heck a NMEA network is and why is it doing this.

[bowhuntntxn]

If I were you I would start disconnecting one gauge at a time until your voltage goes back up to 12VDC. That will be the bad component loading down your battery.

Or if you are in a hurry, you could hook up two batteries in parallel, turn it on and follow the smoke.

I reccomend method one.

[ColinR]

I went with option 1. Lol

Actually was outside doing that when you posted but yea started disconnecting feeds into the network till I got my voltage back. Found the bad feed and it is what I believe is a water temperature sensor. Just leaving it disconnected for now, I can just stick my hand in the water to see what the temp is. Lol