Reply
 
Thread Tools Search this Thread Display Modes
 
Old 05-22-2022, 10:05 PM   #1
Member
 
City: Monterey, CA
Vessel Name: Scrimshaw
Vessel Model: 1990 GB 42 Classic
Join Date: Jan 2020
Posts: 17
Amp hour shunt melted

On our new-to-us 1990 GB 42 the survey called out a non-functioning amp hour meter - turns out that's because the shunt actually melted (hmm).

Ideally, we'd like to find an exact replacement - 2nd best is a newer 'compatible' shunt and of course last resort is to replace the gauge and shunt

The main part of the shunt has the inscription:

VDO Made in Germany
10/87 03 330/114

The brass terminal connector says:

108 6mV 80A

I can't tell if that's 108.6 mV (that seems odd) or 6mV? And what does 108 mean?

Does anyone know the actual spec for this shunt?

Thanks!
jwag956 is offline   Reply With Quote
Old 05-22-2022, 10:14 PM   #2
Veteran Member
 
City: Michael
Vessel Name: Piaro
Vessel Model: Rinker 24
Join Date: Apr 2022
Posts: 29
What is the max amp reading on the meter itself, and a part number if you can read it?
Piaro is offline   Reply With Quote
Old 05-22-2022, 10:22 PM   #3
Member
 
City: Monterey, CA
Vessel Name: Scrimshaw
Vessel Model: 1990 GB 42 Classic
Join Date: Jan 2020
Posts: 17
-80 to +80 Amp - alas I am away from the boat so no part number...

I've attached pics of gauge and shunt
Attached Thumbnails
IMG_2466.jpg   ammeter.jpg  
jwag956 is offline   Reply With Quote
Old 05-22-2022, 10:30 PM   #4
Senior Member
 
HTurner's Avatar
 
City: Corpus Christi
Vessel Model: Willard Vega Horizon
Join Date: May 2021
Posts: 375
Quote:
Originally Posted by jwag956 View Post
On our new-to-us 1990 GB 42 the survey called out a non-functioning amp hour meter - turns out that's because the shunt actually melted (hmm).

Ideally, we'd like to find an exact replacement - 2nd best is a newer 'compatible' shunt and of course last resort is to replace the gauge and shunt

The main part of the shunt has the inscription:

VDO Made in Germany
10/87 03 330/114

The brass terminal connector says:

108 6mV 80A

I can't tell if that's 108.6 mV (that seems odd) or 6mV? And what does 108 mean?

Does anyone know the actual spec for this shunt?

Thanks!

The part # is VDO N03-330-114.


The closest part I could find online has been discontinued (VDO N03-330-116) but available:


https://vdo-webshop.nl/en/ammeter-sh...178728721.html
HTurner is offline   Reply With Quote
Old 05-22-2022, 10:32 PM   #5
Veteran Member
 
City: Michael
Vessel Name: Piaro
Vessel Model: Rinker 24
Join Date: Apr 2022
Posts: 29
Here's the data sheet i believe:


https://www.vdomarinegauges.com/wp-c...e-Ammeters.pdf


And it apparently is 108.6 mv at 80 amps of current
Piaro is offline   Reply With Quote
Old 05-22-2022, 10:52 PM   #6
Guru
 
C lectric's Avatar
 
City: Gibsons, B.C., Canada
Vessel Name: Island Pride
Vessel Model: Palmer 32'
Join Date: Oct 2007
Posts: 3,903
Before just replacing the shunt ask yourself why it melted. Most likely the draw was far beyond its capacity. Overload them badly enough and they become a fuse, a poor one though.

Look around at your electrical system:
--What is the output of the alternator?
--do you have an inverter and what can it draw? What is its output rating?
--Battery charger?
--thrusters?
and so on.


80 amps these days is not a lot with large battery banks, inverters, thrusters, larger alternators. THe load may not be continuous long term but there is a reason it melted.
C lectric is offline   Reply With Quote
Old 05-22-2022, 11:05 PM   #7
TF Site Team
 
Comodave's Avatar
 
City: Au Gres, MI
Vessel Name: Black Dog
Vessel Model: Formula 41PC
Join Date: Jul 2015
Posts: 15,835
Quote:
Originally Posted by C lectric View Post
Before just replacing the shunt ask yourself why it melted. Most likely the draw was far beyond its capacity. Overload them badly enough and they become a fuse, a poor one though.

Look around at your electrical system:
--What is the output of the alternator?
--do you have an inverter and what can it draw? What is its output rating?
--Battery charger?
--thrusters?
and so on.


80 amps these days is not a lot with large battery banks, inverters, thrusters, larger alternators. THe load may not be continuous long term but there is a reason it melted.
+1. Probably underrated.
__________________
Boat Nut:
If you are one there is no explanation necessary.
If you aren’t one, there is no explanation possible.
Comodave is offline   Reply With Quote
Old 05-23-2022, 01:51 AM   #8
Senior Member
 
grahamdouglass's Avatar
 
City: Vancouver Rowing Club, Coal Harbour, Vancouver, B.C.
Vessel Name: Summer Wind 1
Vessel Model: Marine Trader 41
Join Date: Nov 2012
Posts: 330
I just installed a new blue seas DC panel for my 12 volt loads (8380). It has 22 circut breakers and a DC volt meter for 3 battery banks and an 0 - 100 amp meter. The amp meter has a shunt with a 50ma/500 amp capacity. I think you could just get a larger shunt and it should work fine.
grahamdouglass is offline   Reply With Quote
Old 05-23-2022, 06:21 AM   #9
Senior Member
 
City: St. Petersburg
Join Date: Oct 2007
Posts: 328
#8:
Quote:
50ma/500 amp capacity
That should be 50mV/500A.
__________________
Charlie Johnson
ABYC Master Technician
CharlieJ is offline   Reply With Quote
Old 05-23-2022, 07:46 AM   #10
Guru
 
wkearney99's Avatar
 
City: Bethesda, MD
Vessel Name: Solstice
Vessel Model: Grand Banks 47 Eastbay FB
Join Date: Feb 2018
Posts: 1,852
Also note that current draw can become excessive if there's too much resistance due to corrosion and/or poor connections. Wire that's gotten corroded inside the insulation can lead to problems too. The simplest way to test this is to measure voltage drop between sections while there's a load active (stuff is turned on and working).
__________________
-- Bill Kearney
2005 Eastbay 47 FB - Solstice, w/Highfield CL360 tender
wkearney99 is offline   Reply With Quote
Old 05-23-2022, 09:13 AM   #11
Valued Technical Contributor
 
DavidM's Avatar
 
City: Litchfield, Ct
Join Date: Aug 2012
Posts: 6,293
That shunt/ammeter is not a typical type installed on boats and almost certainly is too small. You can replace it with one from Blue Seas or even better with a battery monitor that gives amps, amp hours used and percent charged. Victron makes a good one.

David
DavidM is offline   Reply With Quote
Old 05-23-2022, 09:37 AM   #12
Guru
 
twistedtree's Avatar
 
City: Walkabout Creek
Join Date: Jan 2013
Posts: 7,714
Any chance of seeing a picture of what melted? If you have power on the boat then the shunt it still working. My guess is that it's the plastic mounting around it that melted. Does the ammeter work at all?
__________________
MVTanglewood.com
twistedtree is online now   Reply With Quote
Old 05-23-2022, 10:12 AM   #13
Member
 
City: Monterey, CA
Vessel Name: Scrimshaw
Vessel Model: 1990 GB 42 Classic
Join Date: Jan 2020
Posts: 17
Thanks for all the input - I realize that the question was somewhat GB specific and didn't give enough overall information.

First and most important - this ammeter/shunt is measuring (I believe) alternator to battery. With engines off, it reads 0 (on the port side that works). The result is that under power, we aren't charging batteries. On shore power etc. everything is fine. And for the record, we don't have an inverter.

The alternator was replaced by PO - it is a Wilson 90-17-8067 - which on the Wilson site claims 55A though I have seen other parts sites list it as 80A.

My *guess* is that the old alternator went berserk and fried the shunt - PO didn't notice that and just replaced alternator. Our marine survey tested that alternator functioning properly (but apparently didn't check that it was actually charging the batteries under way)
jwag956 is offline   Reply With Quote
Old 05-23-2022, 10:13 AM   #14
Member
 
City: Monterey, CA
Vessel Name: Scrimshaw
Vessel Model: 1990 GB 42 Classic
Join Date: Jan 2020
Posts: 17
Thanks - I believe that shunt/gauges come matched - can't just replace a shunt and expect the gauge to work/be accurate.
jwag956 is offline   Reply With Quote
Old 05-25-2022, 07:53 AM   #15
Guru
 
City: Olympia
Vessel Name: Rendezvous
Vessel Model: Blue water 40
Join Date: Aug 2021
Posts: 529
Whenever I had a sweep amp meter like that I considered it more of a “at a glance” indicator that the alternator was working. Plus side good, minus side bad.
Now I’m more likely to replace that gauge with a volt meter. Better information in my opinion.
Everyone’s situation is different though, I understand all the things that come into play if changing out something on the dashboard. Good luck with it.
Bmarler is offline   Reply With Quote
Old 05-25-2022, 10:02 AM   #16
Guru
 
City: Boston
Vessel Name: Adelante
Vessel Model: IG 30
Join Date: Nov 2016
Posts: 1,413
Quote:
Originally Posted by jwag956 View Post
Thanks - I believe that shunt/gauges come matched - can't just replace a shunt and expect the gauge to work/be accurate.
Correct. For example, all Blue Sea Systems ammeters read full scale deflection at 50mv. A 75mv or 100mv shunt would not give accurate readings.
SoWhat is offline   Reply With Quote
Old 05-25-2022, 10:41 AM   #17
Guru
 
Marco Flamingo's Avatar
 
City: Dewatto
Vessel Name: CHiTON
Vessel Model: Tung Hwa Clipper 30
Join Date: Jan 2020
Posts: 758
Quote:
Originally Posted by Bmarler View Post
Whenever I had a sweep amp meter like that I considered it more of a “at a glance” indicator that the alternator was working. Plus side good, minus side bad.
Now I’m more likely to replace that gauge with a volt meter. Better information in my opinion.
When I replaced my amp meter with a volt meter (same brand/style fit the dash hole), I saw that the old amp meter had a nice big unfused wire running from the ER to the helm, then to the upper helm, then to ground. Not something I really wanted on a 40 year old boat given that the information provided was minimal. A fused volt meter spliced into the helm instrumentation gives the same "at a glance" info. Generally, below 12 bad, above 12 good, above 15 bad.

As part of the same project, I also installed a modern battery monitor (not in the helm cluster as it didn't match the original gauges). For $50, you get all the digital info you need (amps and volts to several decimal points), including a countdown on the actual amp hours that you have used while at anchor.
__________________
Marco Flamingo
Marco Flamingo is offline   Reply With Quote
Old 05-26-2022, 04:32 PM   #18
Member
 
City: Monterey, CA
Vessel Name: Scrimshaw
Vessel Model: 1990 GB 42 Classic
Join Date: Jan 2020
Posts: 17
Quote:
Originally Posted by wkearney99 View Post
Also note that current draw can become excessive if there's too much resistance due to corrosion and/or poor connections. Wire that's gotten corroded inside the insulation can lead to problems too. The simplest way to test this is to measure voltage drop between sections while there's a load active (stuff is turned on and working).
Interesting - I was thinking of disconnecting the lead and measuring resistance. So if I am understanding your suggestion - in this case I have a (big) wire from the alternator to shunt, and one from shunt to battery. So I would measure voltage at the alternator (when running), then voltage at shunt and finally voltage at battery to make sure neither of the 2 wires is seriously compromised?
jwag956 is offline   Reply With Quote
Old 05-27-2022, 07:58 AM   #19
Guru
 
City: Olympia
Vessel Name: Rendezvous
Vessel Model: Blue water 40
Join Date: Aug 2021
Posts: 529
Quote:
Originally Posted by jwag956 View Post
Interesting - I was thinking of disconnecting the lead and measuring resistance. So if I am understanding your suggestion - in this case I have a (big) wire from the alternator to shunt, and one from shunt to battery. So I would measure voltage at the alternator (when running), then voltage at shunt and finally voltage at battery to make sure neither of the 2 wires is seriously compromised?
You can test sections of wire by setting you meter to dc volts. Put one lead on one end of the wire and the other lead on the other end. Put the leads on the terminal, not the wire. That way you get the crimp connector in the measurement.
The higher volt reading you get, the bigger the voltage drop. Your operating voltage is battery volts minus the meter reading.
Ideally, you only want to see millivolt readings.
Bmarler is offline   Reply With Quote
Old 05-27-2022, 09:51 AM   #20
Guru
 
wkearney99's Avatar
 
City: Bethesda, MD
Vessel Name: Solstice
Vessel Model: Grand Banks 47 Eastbay FB
Join Date: Feb 2018
Posts: 1,852
Quote:
Originally Posted by Bmarler View Post
You can test sections of wire by setting you meter to dc volts. Put one lead on one end of the wire and the other lead on the other end. Put the leads on the terminal, not the wire. That way you get the crimp connector in the measurement.
The higher volt reading you get, the bigger the voltage drop. Your operating voltage is battery volts minus the meter reading.
Ideally, you only want to see millivolt readings.
This is the concept most don't understand. While you have an active load on the wire, measure from two points on the wire. You should not see much difference between the two points. If you do then that stretch between the points you're measuring is bad.

You're not checking voltage between +/-, you're, basically, using the meter as an alternative path for the electricity. If the wire is good then the flow won't favor the meter and you'll see only millivolt values. But if the flow is bad then some portion of it will try to follow the path through the meter, and that can be measured. You should do this on BOTH the positive AND the negative sides of the circuit. Because the circuit depends on all parts of it being in good shape, not just the 'hot' side.

This link covers the idea pretty well: https://www.hagerty.com/media/mainte...-voltage-drop/
__________________
-- Bill Kearney
2005 Eastbay 47 FB - Solstice, w/Highfield CL360 tender
wkearney99 is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Trawler Port Captains
Port Captains are TF volunteers who can serve as local guides or assist with local arrangements and information. Search below to locate Port Captains near your destination. To learn more about this program read here: TF Port Captain Program





All times are GMT -5. The time now is 11:11 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2022, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012