Reply
 
Thread Tools Display Modes
 
Old 11-14-2012, 11:34 AM   #41
Scraping Paint
 
City: Fort Lauderdale
Vessel Model: CHB 48 Zodiac YL 4.2
Join Date: Oct 2007
Posts: 3,804
I guess guys can stop "tooling for a number out there that doesn't exist" now.
__________________
Advertisement

RickB is offline   Reply With Quote
Old 11-14-2012, 11:36 AM   #42
Guru
 
Moonstruck's Avatar
 
City: Hailing Port: Charleston, SC
Country: USA
Vessel Name: Moonstruck
Vessel Model: Sabre 42 Hardtop Express
Join Date: Nov 2008
Posts: 7,848
Quote:
Originally Posted by Forkliftt View Post
True. Or the increased resistance of a cold engine.
All of that was in Stray-Cats formula. Didn't you see it?
__________________

__________________
Don on Moonstruck
Sabre 42 Hardtop Express & Blackfin 25 CC
When cruising life is simpler, but on a grander scale (author unknown)
http://moonstruckblog.wordpress.com/
Moonstruck is online now   Reply With Quote
Old 11-15-2012, 07:10 AM   #43
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 16,524
"Really, what danger is that? Has there been a rash of shunt induced boat fires "recently?

The danger is when the Start button is pushed , there is not even the sound of a click.

A "Much Ungood" way to start the day.
FF is offline   Reply With Quote
Old 11-15-2012, 07:28 AM   #44
Scraping Paint
 
City: Fort Lauderdale
Vessel Model: CHB 48 Zodiac YL 4.2
Join Date: Oct 2007
Posts: 3,804
Quote:
Originally Posted by FF View Post

The danger is when the Start button is pushed , there is not even the sound of a click.

Would you be so kind as to explain the sequence of events that would lead to such an event?

Has there been a rash of shunt failures lately that have caused loss of DC power on boats?

It makes for a nice throwaway line FF but unless you can back it up with some examples and tell where the failure would occur and for what reason I think you are just blowing smoke ... and none of that smoke is from overheated electrics.

If you are afraid of shunts and can't sleep at night maybe a Hall effect sensor would take some of the fear out of your boating experience and still deliver the information you want.
RickB is offline   Reply With Quote
Old 11-15-2012, 08:17 AM   #45
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 16,524
A shunt in a start circuit such a poor practice that an example of starter shunt failure is hard to show.

A shunt in the house side is very desired IF one widhes to monitor the SOC.

Asking for a shunt starter failure is on par with asking for examples of 60 ft boats blown ashore because their 1/4 inch anchor line failed.

1/4 inch tie up is very common on moorings when the boat is being "sold" to the insurance co, but sort of rare otherwise.
FF is offline   Reply With Quote
Old 11-15-2012, 09:15 AM   #46
Scraping Paint
 
City: Fort Lauderdale
Vessel Model: CHB 48 Zodiac YL 4.2
Join Date: Oct 2007
Posts: 3,804
The sky is not falling and placing a shunt in the starting circuit is not "bad practice."
There are thousands of high current DC shunts installed in motor and other power circuits onboard ships where the current flow far exceeds a tiny engine starter.

What is it about a shunt that freaks you out so much? Why is it so much more dangerous than a cable terminal or - gasp - a battery terminal?

This is the kind of myth and "sea story" nonsense that make small boat mechanics and electricians rich ... people read utter nonsense on boating forums and actually believe it even though the people who post the garbage can't support their position with anything more than rumors and their "net creds."

I challenge you to show us why a shunt installed correctly with clean terminals that are properly tightened is any more likely than any other electrical component to fail and cause the sky to fall.

http://www.megacon.com/admin/uploads...ton.Shunts.pdf
RickB is offline   Reply With Quote
Old 11-16-2012, 07:04 AM   #47
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 16,524
I challenge you to show us why a shunt installed correctly with clean terminals that are properly tightened is any more likely than any other electrical component to fail and cause the sky to fall.

A shunt installed "correctly" would have to be large enough to take the LRC of the staterr motor.

This can be 2x to 7x the running current of the starter.

With a say , 1000A or 2000A shunt , what purpose would the setup serve , its accuracy at the minor DC loads of lighting or a bilge or water pump would be outside the accuracy percentage of most SOC monitoring systems.

So as already asked , why bother to monitor the starter for 5 seconds , when the 24/7 ships use of charge and discharge is probably the desirement?
FF is offline   Reply With Quote
Old 11-16-2012, 07:30 AM   #48
Scraping Paint
 
City: Fort Lauderdale
Vessel Model: CHB 48 Zodiac YL 4.2
Join Date: Oct 2007
Posts: 3,804
Keep trying FF, maybe some day you will find a reason to believe your own myths.

Quote:
"why bother to monitor the starter for 5 seconds?"
Because it is his boat and his desire to do so ... your boat and your desires don't count. Just because you wouldn't do something doesn't mean you have to create some fantasy about why someone else should not do it.
RickB is offline   Reply With Quote
Old 11-16-2012, 09:46 AM   #49
Guru
 
City: Carefree, Arizona
Country: usa
Vessel Name: sunchaser V
Vessel Model: DeFever 48
Join Date: Apr 2008
Posts: 6,363
Meridian

I recently had a well known yard install a new Magnum 2800 inverter charger and two battery monitor kits (BMK) on our vessel. One could assume these BMKs use shunts. One BMK was for the house batteries and the other for the main engines. The purpose of the BMK for the house batteries is hopefully obvious to those reading this thread. The engine start BMK was installed to insure that I know the operating and at rest health of the 2 8D engine batteries and related charging systems.

This entire system is nicely monitored by Magnum's ER mounted modem and helm location remote. I chose Magnum because they are like my boat, located in the PNW. Had I been on the East Coast, I may have considered Victron.

These 21st century operating and monitoring systems are well worth the cost for the type of remote cruising we do. If you care to, I'd suggest you talk with the suppliers and recognized marine electricians for any shunt related fears and phobias related to this thread.

In my industrial experience shunts are everywhere, with the most interesting on a 0 to 18 RPM electric motors (you read that right, 18).
__________________

sunchaser is offline   Reply With Quote
Reply

Thread Tools
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





All times are GMT -5. The time now is 09:48 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012