Electrical issue with 1988 Cajun bass boat

[Bannister 6905]

I just purchased a 1988 Cajun 19' bass boat and have discovered a serious electrical issue that has me off the water until I can get it resolved. In the process of troubleshooting the issue (low voltage to the live well pumps and bilge pumps) I have come across what looks like a capacitor that is wired into the power distribution block (see attached photo). Does anyone recognize this set up and what is the function? Background - When I measure voltage going into the block, it checks 12.6V. The positive connection that attaches to the cap(?) also measures 12.6V. However, when I connect my voltmeter to the "other" unmarked lug on the "cap", I measure around 8V...that value never changes, even when I remove the "cap" from the circuit. When I check the voltage on the "cap" removed from the circuit, it measures 0.3V negative, when the meter is connected + to + and neg to the other lug. Any ideas? Thanks. Bannister

 

[wrench 3]

I'm wondering if it's something that someone added for radio static suppression. How is it wired into the system?

 

[sam am I]

If the cap is just across the helm's primary 12VDC, most likely just added to minimize noise to anything at the helm you'd hook up to this 12VDC (looks like three things already, maybe two and the feed, hard to see)...FF, Radio, VHF, etc....Just a filter cap is all.

Your 8V issues sounds like the cap's ground is flaky...The term block looks corroded!

 

[Bannister 6905]

Thanks for the information - I tried cleaning the attachments from the block to the cap and that made no diff. I'll take a closer look at the rest of the block itself. I didn't see anything serious so far, but better safe than sorry!
I'll try eliminating the cap and see how that affects voltage. Also, I'll verify there are no shorts in the wiring going from the bar to the switches.
Bannister

 

[sam am I]

Use the battery's neg post as your main "mother earth" reference......i.e., connect the volt meter's negative lead to the batt's neg post (the lead-Pb part) and leave it there. Now using the meters positive lead probe things.....

As you probe things with the positive lead of the meter, ALL grounds (usually blk wire) even the unmarked (neg) post of the cap, if wired properly, should NOT read anything higher than 0'ish volts......If so, you have flaky ground somewhere allowing its ground to "float" up above the battery's 0V terminal voltage .......hence "8V".

Same goes with the positive stuff, with the meter's neg lead STILL attached at the "mother earth ground referance point".........Any 12VDC feeds have to be 12V'ish, else you have a flaky connection in the 12V feed lines allowing the 12V to "sag" below the battery's terminal voltage of 12V'ish

 

[Bannister 6905]

That sounds like a plan - I'll let you all know what I find!

 

[Bannister 6905]

IMG_0980.jpg Well, issue resolved. The second aerator pump is totally frozen and was causing the electrical issues...Whew!

 

[Bannister 6905]

 

[sam am I]

Very cool!!....glad you found issues.

What concerns me a tad bit still is why a fuse never blew? Esp since the motor was locked up? I'd think, unless that pump had internal protection, you should have been either a) heating wires red hot and/or b) blowing fuse/s.

Hmmm....that is unless you had a flaky connection somewhere in a feed limiting current.....Limiting it such that a voltage drop of 4V (12V-8V = 4V, recalling your "8V" measurement) volts exists in series with it....

Guess I'm suspect still you have connection issues lurking about somewhere