Electrical bug...
 

Ok stumped on this 1. After I installed stereo system sometime during the winter months my boat came up with a weird bug. First off it's a 98' sport nautique with a gt40. I installed 3 amps running to distribution blocks and 2 batteries ran as a bank to a perko plus a starting battery,1,2 & all. So the bug is all of a sudden my voltage meter is pinned to 18 when boats running. When auxiliary is on it's at 12ish then after starting it's pinned. When i honk my horn all the gauges bog down as well if I turn the stereo all the way up and the bass hits. I swapped out the 2 banked batteries cuz they were 5 years old,no help. Then assumed it had to be a grounding issue went through and tighten and cleaned all my grounds. No help. The boat does have a 20 amp charger to tend the batteries. Any suggestions? I also checked all the daisy chained grounds in the dash all seem to be solid.

Alternator regulator is shot. It's what ensures the voltage stays around d 14.4V while running. I would not keep running the boat until you fix or you may fry electronics real quick!

What makes you come to this conclusion?

Is there a way to test it?

Because a alternator should never exceed 14.4V when it is making power. If it is, the voltage regulator inside and has gone bad. Remove the alternator and take it to an auto parts store to test it, like NAPA.
Years of working on cars is why I came to this conclusion.

I agree the alternator is full fielding .Not only can you really screw up electronics you can cook your batteries and even cause a fire .

You can easily test this by disconnecting the pos and neg from the alternator (to avoid doing more damage) and putting a voltmeter on it while the engine is running. That will isolate the alternator from all other electronics and tell you how much voltage your alternator is putting out.

Thanks guys everything I've researched is pointing to alternator. Sourced out the upgraded 100 amp alternator going to pick up today and install it after I test mine at atozone

The fact hole time I figured it was a bad ground. Fml

Make sure you get or only use a Marine alternator. Automotive alternators are Not shielded and they can in some cases cause a explosion. Error on the side of safety

Yup

Starters even more so.

Well alternator didn't fix it. Fml just threw $ at a problem like a *******. At least I got a upgrade.

Electrical bug...
 

That makes no sense. How can a new alternator put out more than 14.4V? You didn't wire the 2 batteries in series to make it 24V did you?
Remove those extra battery you added, completely from the system, and try that. If you want to run two batteries together, they have to be wired in parallel! Like this:
https://uploads.tapatalk-cdn.com/201...724d905eaa.gif
If you wired them in series then you get 24V per the image on the right below which is bad!
https://uploads.tapatalk-cdn.com/201...25be05a50.jpeg

lol they are ran correctly that's the first thing I double checked. Don't even know if the boat would run like that?

I don't know what to tell you then. I have heard of replacement alternators being bad too. Aside from the batteries it's the only voltage source. Did the replacement alternator wire up exactly the same as your original one? The other thing I would check is to see what voltage it is producing not connected to anything, but while spinning

You must have some sort of wiring issue that is back-feeding or looping power back into the circuit.

I would start over with your battery wiring. Try posting a diagram here of exactly what you've done.

Someone did this same thing on themalibucrew.com and he totally botched the wiring and had similar symptoms. You should have tested the Alternator voltage output before spending hundreds of dollars on a new one.

Man I know I took the old 1 off to get it tested 3 places couldnt test due to they couldn't find a cross reference. At that point I was like f it. Worst case scenario I upgraded my alternator. Building and nuts and bolts I'm great at but electrical systems I'm horrible at. Going to buy a volt meter today and learn how to use it.

Has to be a battery wiring issue...show us a diagram and pics of what you did.

How about this. Take out ONE of the extra batteries you added and see what happens. I still think that they must be feeding in series.....I know you said otherwise, but call me stubborn.

When I get home I'll disconnect them to see. I mean I do chief a lot but not that much! If it running 24v wouldn't that tiatally screw everything up?

depends on what you're running. short answer, yes. wiring in series its about the only way to get more than 14 volts out of a 12 vt battery system

What he said. Try running with JUST the main battery for the boat. If you voltage is good, then its highly probable you wired the other 2 in series.

FML!! Bad gauge! Lol at least I have a upgraded alternator and a back up now. I've never owned or operated a multimeter,it's my favorite tool now. Can't believe all the years building houses,working on everything I have cuz I refuse to pay another man to a job I can do myself,lol, I've never owned this tool. Gauge is getting 14.2v but reading 18++. I did my own install on my stereo,and it's clean af and sounds awesome, knew I wired everything correctly even checked yesterday to be sure and man you guys had me doubting myself. Cheers! Time for some DUBS basketball.

Cool!

that's great news!

I got on here this moring to write I still think its a bad gauge.


Only because the gauge on my supra reads low and I chased my tail a few summers ago. Until I put a multimeter on the alternator.

Ya I left my charger off for 6 days with my ignition fuse in making my batteries low and didn't realize alternators don't start working until 2k rpms or so. I have 20 min 5 mph to fast water so no charge there and was getting weird symptoms of low power. But I'm stoked to know my boats tip top and I learned a bunch of stuff.

Awesome news dude !!! Can you order a new gauge for it ?