Cruisers Forum
 


Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 21-10-2008, 10:00   #1
Registered User
 
S/V Mother Ocean's Avatar

Join Date: Nov 2005
Location: Beaufort, SC
Boat: Lagoon 37 Catamaran
Posts: 54
Battery Shunt ? ? ?

What the #$%@ is a battery shunt? & Why do I have/need one?

Ok, I have this french built boat, and it has 2 starting/house banks of batteries, 2 T-105s on each side as both house and starting banks. They are split in to 2 seperate banks. I am instaling a starting bank of group 27s, 1 at each engine and going with the T-105s as a single house bank of 4 T-105s in series/paralle (spl?).

The battery switches are a Positive switch for each side (total of 2), 1 negitave switch for both sides and then a postive "SHUNT" switch. Why ?
Dan
__________________
Mother Mother Ocean, I've heard you call, I've wanted to sail upon your waters since I was 3' tall.

S/V Mother Ocean
S/V Mother Ocean is offline   Reply With Quote
Old 21-10-2008, 17:19   #2
Registered User
 
Aussiesuede's Avatar

Join Date: May 2008
Location: Vancouver, BC & Seattle, WA
Posts: 639
Quote:
Originally Posted by S/V Mother Ocean View Post
What the #$%@ is a battery shunt? & Why do I have/need one?

Ok, I have this french built boat, and it has 2 starting/house banks of batteries, 2 T-105s on each side as both house and starting banks. They are split in to 2 seperate banks. I am instaling a starting bank of group 27s, 1 at each engine and going with the T-105s as a single house bank of 4 T-105s in series/paralle (spl?).

The battery switches are a Positive switch for each side (total of 2), 1 negitave switch for both sides and then a postive "SHUNT" switch. Why ?
Dan
In the most basic terms. A shunt is a resistor in the circuit to control current. (Think Voltage regulator in your car.)

You have to have a means of measuring/regulating both the power coming from your batteries, as well as the power going into them. Without knowing both, you could never get an accurate measurement of the state of charge and would be prone to over-charge or over-discharge. All the shunt is doing is measuring/regulating the current going in and out of the battery so it can assess & manage battery charge levels. It's a bit curious that yours says "positive" at your switch unless they are trying to imply that "Positive" simply means "On" (ie opening the circuit for measurement/regulation?) Still kinda odd imo
__________________
I'm On point, On task, On message, and Off drugs. A Streetwise Smart Bomb, Out of rehab and In denial. Over the Top, On the edge, Under the Radar, and In Control. Behind the 8 ball, Ahead of the Curve and I've got a Love Child who sends me Hate mail. - (George Carlin)
Aussiesuede is offline   Reply With Quote
Old 21-10-2008, 17:39   #3
Registered User
 
AnchorageGuy's Avatar

Join Date: Mar 2003
Location: Wherever the boat is!
Boat: Marine Trader 34DC
Posts: 4,619
Areyor sure this is a shunt or perhaps a high amp fuse bar?
__________________
Chesapeake Bay, ICW Hampton Roads To Key West, The Gulf Coast, The Bahamas

The Trawler Beach House
Voyages Of Sea Trek
AnchorageGuy is offline   Reply With Quote
Old 21-10-2008, 18:22   #4
Moderator Emeritus
 
David M's Avatar

Cruisers Forum Supporter

Join Date: Sep 2007
Location: Eastern Tennessee
Boat: Research vessel for a university, retired now.
Posts: 10,406
It is very common to measure the amount of current flowing into or out of a battery. This may be the purpose of your battery shunt.

Besides what was mentioned above, shunts can also be used for determinng current. The voltage difference across a shunt is directly proportional to current flow through the shunt. Analog ammeters that use shunts are actually volt meters with the scale in ampres. There are also digital ammeters that use shunts. Shunts are typically 500mV shunts which means a current of 500 amps flowing through it creates a voltage difference of 500mV or 0.5 volts. 50mV shunts are also common.

They typically look like this:


Is this what you have? If there are two smaller wires that lead from each side your shunt to an ammeter, then there is your answer.
__________________
David

Life begins where land ends.
David M is offline   Reply With Quote
Reply

Tags
battery

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Best Battery cburger Electrical: Batteries, Generators & Solar 50 04-12-2007 10:26
battery replacement irwinsailor Electrical: Batteries, Generators & Solar 30 26-07-2006 05:40
Battery charger to replace battery? lilly Electrical: Batteries, Generators & Solar 5 22-07-2006 18:11
link 10 shunt on +? Ryan Electrical: Batteries, Generators & Solar 6 27-09-2005 14:17
BATTERY VALUE GordMay Electrical: Batteries, Generators & Solar 5 17-07-2003 21:42

Advertise Here


All times are GMT -7. The time now is 01:25.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.