Perfect Pass beeping and gauges cutting out

[mikemcclain8]

I am finally getting to the boat today and started it. Both batteries are sitting at 12.7 and 12.8. Start the boat no problem, but voltage gauge only says 12 while running. I check both batteries and they are at 13.3-13.4 while running. Check output on alternator and have 14 volts which is what I would expect. Am I missing something here?

On a side note, I turned the battery switch to both off (thats how I test alternators usually at work) and the engine kept running but the PP was beeping like crazy and the voltage gauge was spiking. Seriously, I need to know if there is a problem or I am going crazy. Thanks for any replies.

I had this happen this summer when hitting choppy water. Mine ended up being the wire that runs to the nut on the back of the tach. Sounds like you've already checked that, but I had trouble reproducing with a wire wiggle until I got under the helm.

[dmaxx04]

how is your switch wired? you said you had 13.3-13.4 on both batteries while running, what position was the switch in?

I had the switch on one battery. Every way I turned the switch, the batteries stayed the same except for when I turned it completely off.

[tigemech]

hmm do you have a battery isolator? both batteries should not be charging if the switch is just on one battery. One battery should be used for cranking, and the other used as a house battery. Id be curious as to how the batteries are wired.

[dmaxx04]

That is a good point. I should probably take the isolator off and check it out. I know the positive cables are separated at the isolator. The ground cables go from the starboard battery to the port side, then to the ground on the engine. You think the isolator has corrosion on it and isn't working anymore? I don't have the automatic iso, just the perko switch.

[tigemech]

Sorry for the confusion, but you have a perko switch, and a battery isolator? Or just the switch, the switch itself isnt an isolator.

[dmaxx04]

I have just the perko switch.

[dmaxx04]

I took the boat out on Tuesday and ran in the lake. Checked batteries while running and monitored voltage at the batteries all day. The switch worked correctly and I could watch the voltage go up and down(slowly) as I switched between 1/2/combined and everything is working correctly. I didn't have any problems at all, charging wise. The batteries were always at around 13.5-13.8. My gauge up front never went above 13 though. This is the only problem I see. Could there be that much of a voltage drop from the rear to the front?

[IDBoating]

A bad ground is a common cause of a voltage drop like that. A voltmeter can often measure a voltage difference across a bad ground - even though "it's all metal!" and "I can see both sides!". That voltage difference can show up as weird problems like the one you're describing.

Your boat is 12-13 years old. Might be time to go through the grounds, starting at the batteries and starter and working outwards toward the helm and other systems.

I have checked all the wiring for voltage and multiple points for continuity. Checked all grounds for continuity off the batteries for sure.

"Continuity" is not the same as a good ground (or other connection). How are you measuring continuity? An ohmmeter, preferably a digital one, is the only way to be sure.

Before you start, though, here's a quick test: What does a voltmeter say the voltage is between the big B+ and Ground bus bars under the helm? I'd trace along from there, heading toward the gauge(s) that are giving you the low voltage reading. I bet the gauge(s) are reading properly - there's a voltage drop between them and the "voltage at the batteries".

[freeheel4life]

Dmaxx,
So I am probably going to start a debate here, but in my experience turning off battery switch while engine is running is a no no. Good way to lose diodes in the rectifier and then induce "AC leakage" which can cause problems as well. Worth checking alternator output with meter in AC to confirm or deny.
At this point though you've gone thru enough diagnosis to know without a doubt that your alternator is functioning. Batteries are good. You can chase a voltage drop/skewed reading at gauge and get it perfect, or know that if it reads less than 12 you have problems. Good luck. Keep posting results.

[chpthril]

No debate, NEVER turn main battery switch off with engine running. Creates a full-field scenario for the alternator, leading to a smoked unit.

[dmaxx04]

A bad ground is a common cause of a voltage drop like that. A voltmeter can often measure a voltage difference across a bad ground - even though "it's all metal!" and "I can see both sides!". That voltage difference can show up as weird problems like the one you're describing.

Your boat is 12-13 years old. Might be time to go through the grounds, starting at the batteries and starter and working outwards toward the helm and other systems.

"Continuity" is not the same as a good ground (or other connection). How are you measuring continuity? An ohmmeter, preferably a digital one, is the only way to be sure.

Before you start, though, here's a quick test: What does a voltmeter say the voltage is between the big B+ and Ground bus bars under the helm? I'd trace along from there, heading toward the gauge(s) that are giving you the low voltage reading. I bet the gauge(s) are reading properly - there's a voltage drop between them and the "voltage at the batteries".

You make a good point on the grounds and age of the boat. I will start pulling the grounds off at the engine and cleaning any corrosion on them working out. Would you just replace these ground cables?
To answer a couple questions: 1. To check continuity, I started at the ground on the engine and followed it to the first battery. Then followed the each wire that was on the battery at the other side. All was good. 2. I have been using a digital Fluke for all of my testing.

[dmaxx04]

Freeheel and Chp, I have never heard of not turning the switch off, but you have a valid point. No need for debating you guys, I just won't do it anymore. Better safe than sorry.

My plan of action going forward is to clean the grounds up and check the voltage at the helm bus bar like ID said.

Freeheel, your theory is correct as in if it drops below 12 on the gauge, I got problems. Even when I was filling ballast and everything, the gauge didn't drop below 12.5, with the engine running.

[IDBoating]

Would you just replace these ground cables?

I would carefully examine the interface between the lugs on the ends and the cable crimped into them. Might even nibble back the insulation from the lugs a touch to see how the wire looks inside. You can have corrosion hidden in there. If anything looks amiss either trim the cable back and install new lug(s) (if you have the excess cable length) or replace with a new cable. When I replace with new cables, I commonly step up one wire gauge size to further reduce I2R losses.

I have been using a digital Fluke for all of my testing.

Excellent. But I'd take that meter off simple "continuity" and put it on the lowest resistance range. Then when you measure, you will have a quantitative value rather than just a "beep" that says it can see the other side to some unknown extent. I have a Fluke meter like that one, with a continuity function, but I don't know what threshold it uses to say "yep, I have continuity". It might be fine for small signal work but some of those cables you're testing carry hundreds of amps, and I2R voltage drops can be significant with even a small amount of resistance.

[dmaxx04]

I will check all that stuff. Thanks for the inputs. I really appreciate all the help everybody has offered. I will keep y'all posted on what I find.

[RDeLacy]

Dmaxx, I have had similar problems with my 2003 22V. All my gauges would just keep bouncing instead of maintaining the reading. The light on the perfect pass would keep blinking even when I tried to turn it off. I have the cruise PP so it does not beep. I finally pulled the fuse out of the perfect pass and that had fixed the bouncing gauges problem.

After reading this, I will go back and check the grounds on the Perfect Pass, but for now, the PP remains disconnected.