Chasing down an electrical issue

[seasick]

A comment about plotter low voltage alarms:
There is a difference between a low voltage alarm and a reset (shutdown) and that is basically the actual low voltage condition. I also have low voltage alarms turned off on my plotters since I can get an alarm every time, I crank an engine.
Point here is that low voltage alarms may not be anything to worry about but a reset or shutdown is.
I have to be honest; I am not sure anymore what issue we are trying to address Russ, you are a cowboy!

 

[Bloodweiser]

Don't assume that the fuse is under power. Get the spec off of the pump.. If you can't see it. Search online for the spec by using the brand and model number.. Not Good practice to install larger Amp fuses if not needed.

 

[RussGW270]

Lol that was my Navy callsign heh

Anyway, it shut down once, but I had everything turned on. It did not shut down when I had only a few things on. The voltage dropped more as more things kicked in. I think we are drawing too much power and the chartplotter is usually the most picky electronic on the board so, will know more after I get to cleaning.

Am at HD trying to locate plug jumpers, dual prong connectors, in case I need to replace one.

 

[SmokyMtnGrady]

I don't recall your background Russ , so pardon me if I am writing something you already know. Your electronics, the GPS is sensitive to voltage drops. You should think of voltage and amps this way. Voltage is how wide a river is and amps is how fast the water is moving in the river. Your circuit breakers and fuses are controlling the amps going through a circuit. Too much current and you start fires because the conductor heats up.

Something is gobbling up voltage . It's either a loose ground , intermittent wore and or an internal short on a motor. Motors consume the highest amount of amperage at start up. Your bilge pumps need to be on the isolated circuit like mentioned above with a wire directly connected to your battery with an inline fuse. You do have a manual start through a switch on the panel. You could have an internal short on the motor and see the drop.

Too many voltage drops are not good for computers which your plotter is. I would suggest finding this problem and using a multimeter to test the drop and don't turn on the plotter until you figure this out. Good luck.

 

[wrxhoon]

A bit of advice Russ, When you say you will clean terminals with a dremel, that takes off all the tinning and exposes copper then copper will corrode much easier/quicker and it will give you more problems . Not saying you shouldn't clean terminals/connectors, you should but after you put them together spray a bit of battery terminal protector. It doesn't have to be CRC brand. This will protect your connections/ terminals for a long time even on a boat. Don't spray this before you connect them . If you want something to clean them you can get the battery terminal cleaner if you like and follow instructions how to use.



Lol that was my Navy callsign heh
Call sign suits you, sorry I couldn't help myself..

 

[seasick]

Boeshield T9 works well also . Just don't overdo these treatments.

Back to the too many devices causing the voltage drop:
The ABYC spec for conductor sizing state that the allowable voltage drop on a run is either 10% or 3% depending on the type of load. In general, electronic devices like plotters should see a voltage under load that is at least 97% of the voltage at the source, A simple example is a battery that has a standing unloaded voltage of 12.5 volts' if connected to a plotter it should not experience a voltage drop greater than .375 volts or 12.125 volts.
A mechanical load on the other hand would be designed for a 10% allowable drop or 11.25 volts in that case.Think bilge pump
The main feed wire from the accessory breaker near the battery should be sized to prove no more that 3% drop at about ( subject to discussion and arguments) of 80 - 100% of the breakers spec. So in theory if you have a 30 amp breaker, the wires should be sized to carry 30 amps (for a while) and have no more than a 3% drop at the bus bar/fuse panel ( at least at 80% of load or 24 amps). It is critical to remember that the current flows in the positive AND negative (ground) conductors and both need to be sized accordingly. The length of the conductor is needed to look up the proper cable gauge and that length is the total round trip length including the ground. If you installed wires to power a devise 15 feet away, the round trip wire length is at least 30 feet.
That said, the boat would have been wired correctly to carry the current permitted by the original breaker. Of course that could have been changed and perhaps to one larger than permitted size but regardless, the circuit should be able to handle all the original loads as well as some reasonable electronics. Butt kickin monster entertainment systems are often not reasonable loads! Things like plotters, sonar, VHF are generally low draw devices. Things like winlasses and halogen spreader lights or search light are a different story.
My long winded drawn out point is that if you have turned on the typical devices, like GPS, VHF etc, the voltage should not drop more that 3 % at the main bus. If it does, you have wiring issues, not just load issues.

 

[RussGW270]

@seasick yes sir, we pulled the bilge pump and it was seized. When I pulled it out, we tested the voltage and it dropped from 12.6 to like 7 as it was drawing so much voltage to try to spin it up that it was sucking down the draw. So, opened it up and as soon as we broke it free, I heard a “crack” as the salt buildup broke loose.

the voltage returned to normal at that point.

We also tested, prior to breaking it free, the float and same effect.

So, this was due to the bilge pump being stuck. The float was sketchy but either way...once it seized up, rust and corrosion will set in so I am swapping it out, float and all. No sense messing with it since it would randomly seize even in testing.

So, cancelled the trip and am going to look for either an identical Attwood 1700 and float or a Rule 2000 and float.

I started a New thread at the request of othrrs, but updating you here.

Good experience, but would have liked it to last a trip lol.

Weather was turning crap on Sunday anyway.

Thanks for the awesome input.

All my other boats were a lot easier to deal with lol. Needed more light. I could not see the pump at first. The Livewell looks new and is a Rule, so thought I was going nuts trying to locate this one. Was gray and so in the low light it blended in. Add that to the fact the boat was tilted forward, the bilge kept dry, or looked like it, so was like, “water must be going somewhere” and no-one was there to watch for me lol.

Anyway, will take it to the bilge thread as I progress.

 

[Lite Tackle]

Russ, if you have a bad bilge pump and voltage dropped to 7V when you turned it on and the fuse to that pump did not blow, either the fuse rating for that circuit is incorrect or it is not in the circuit. May want to confirm that along with the replacement of pump.