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sail69

Raymarine Low Voltage...

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So started getting battery low warning from instruments (ST-40 and ST-60s) first with engine off, then with engine on.  Batteries are not low per voltmeter.  This happened once last year but mysteriously stopped (and was forgotten).

 

This time Autopilot (on same circuit) is "failing" and the other instruments reading wacky or blinking on and off.   Now with engine off, some wont come back on and some are on but not correct.

 

Checked all the instrument wires.  Checked engine ground and positive and negative connections.  All clean.

 

Before I dig into the dreaded back of the breaker panel morass and working the negative bus bar any suggestions?  I assume its that, but if I can avoid...

 

Thanks in advance.

 

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No way to diagnose this with minimal info. If the back of the breaker panel is dreaded, it's probably for good reasons. One or more of them may be causing your problem. Time to suck it up, dive in, and clean it out. Negative bus bars, tinned wire, new terminals, and proper crimps are your friend.

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Yea I get that...trying to salvage the rest of the season before I start rebuilding.  Was hoping there was a unknown gremlin in the system that I have yet to  check.

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My Raymarine ST6000+ AP would intermittently show a low voltage msg and then shut off all last year.  I pulled all the wire this winter and found a butt splice the previous owner had put in poorly for no apparent reason.  The negative side was corroded and crumbled apart when I pulled on it.  Rewired it and no more problems.  Simple fix.

Inject 12vdc into the SeaTalk bus with a wire from the batteries and see if the problem goes away. 

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48 minutes ago, IStream said:

No way to diagnose this with minimal info. If the back of the breaker panel is dreaded, it's probably for good reasons. One or more of them may be causing your problem. Time to suck it up, dive in, and clean it out. Negative bus bars, tinned wire, new terminals, and proper crimps are your friend.

^^ Correct answer. Today the instruments, next week the radios, then the lights. Maybe even smoke and a fire to liven things up!

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Well, if you're just trying to get by for a few weeks, I'd suggest starting at the AP power connections and working your way backwards. Raymarine likes to power their Seatalk busses with the APs so if you can find a fault with that, you may have an easy fix for both problems. My S3G uses those confounded stranded wire screw terminals where the stripped end is inserted into the cage and a set screw is tightened down on the wire bundle. Periodic re-tightening is advised so if you've got those on yours, and even if you don't, maybe you'll get lucky.

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7 hours ago, IStream said:

Raymarine likes to power their Seatalk busses with the APs so if you can find a fault with that, you may have an easy fix for both problems. 

Stream they actually don't other than to encourage a proper data and power cabling sequence either daisy chained or otherwise. I recall for your S3 they even include instructions on how to disable power from the AP going into the ST buss to avoid having to fire up AP.

7 hours ago, IStream said:

My S3G uses those confounded stranded wire screw terminals where the stripped end is inserted into the cage and a set screw is tightened down on the wire bundle. Periodic re-tightening is advised so if you've got those on yours, and even if you don't, maybe you'll get lucky.

Yes stranded terminals and boats are not a good mix. These are your friend.

images (84).jpeg

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5 minutes ago, jack_sparrow said:

Stream they actually don't other than to encourage a proper data and power cabling sequence either daisy chained or otherwise. I recall for your S3 they even include instructions on how to disable power from the AP going into the ST buss to avoid having to fire up AP.

True dat.

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IIRC, instruments are fused at 0.5 amp while autopilots are fused at 5 amps and up.  I did it anyway by use of an in-line fuse, which I normally hate doing, but the number of circuits in the panel was getting out of hand.  (Don't wanna use the autotiller? Don't plug it in!)  I did buy a set of those crimp-on ferrules last winter, but so far have not remembered that I have them at the appropriate moment.  

As per the OP, as we learn in hi skool, low voltage = high resistance.  Get out thine multimeter. 

 

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2 hours ago, toddster said:

IIRC, instruments are fused at 0.5 amp while autopilots are fused at 5 amps and up.  I

Instrument bus usually 5A and AP say 20A plus depending on drive size.

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Run a wire back to the negative terminal of your battery and use that as a reference negative when you're measuring with your multimeter.

That will eliminate or confirm your earthing / ground / negative connections.

It takes very little to bugger 12 volts.

With a big load (autopilot), poor contacts will get warm and, in the dark, may show a glow / spark.

Wire that has become inflexible is a clue too.

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