Battery grounds: Individual or common? - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > On Board > Gear & Maintenance
 Not a Member? 
  #1  
Old 04-10-2010
cghubbell's Avatar
1977 CS27 ~ Ravat
 
Join Date: May 2009
Location: Ontario, NY (PYC)
Posts: 161
Thanks: 5
Thanked 0 Times in 0 Posts
Rep Power: 6
cghubbell is on a distinguished road
Question Battery grounds: Individual or common?

I've been combing threads and diagrams to no avail, and hoping someone can slam the lid on this question for me...

I have two battery banks (one battery in each bank) on my boat. Is it *best* to take the negative terminal from each battery individually to a ground bus, or to join the two negative terminals, then take it to a ground bus?

When purchased, the boat was wired with the two negative posts joined, but since I'm re-doing almost everything right now and replacing the battery wires it's a now-or-never moment to get it right. Unfortunately, all diagrams seem to just show things going to ground without specifying the actual path... (Or maybe I'm just not in on the secret code!).

Thanks in advance,
Chris
__________________
CS27 #1254 ~ Ravat
PYC, Lake Ontario

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote Share with Facebook
  #2  
Old 04-11-2010
CarelessNavigator's Avatar
Member
 
Join Date: Mar 2007
Location: Grande Prairie, Alberta
Posts: 64
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 8
CarelessNavigator is on a distinguished road
Quote:
Originally Posted by cghubbell View Post
I've been combing threads and diagrams to no avail, and hoping someone can slam the lid on this question for me...

I have two battery banks (one battery in each bank) on my boat. Is it *best* to take the negative terminal from each battery individually to a ground bus, or to join the two negative terminals, then take it to a ground bus?

When purchased, the boat was wired with the two negative posts joined, but since I'm re-doing almost everything right now and replacing the battery wires it's a now-or-never moment to get it right. Unfortunately, all diagrams seem to just show things going to ground without specifying the actual path... (Or maybe I'm just not in on the secret code!).

Thanks in advance,
Chris
There is no secret. Electrically they are the same. Electrons cannot tell the difference one way or the other. Just make sure the size/gauge of the wire is the same or able to handle the batteries you have. Two terminals on one wire = heavier wire gauge. One terminal and cable for each = lighter gauge wire. Most setups I have seen usually put the two terminals on one wire/cable.
Reply With Quote Share with Facebook
  #3  
Old 04-11-2010
cghubbell's Avatar
1977 CS27 ~ Ravat
 
Join Date: May 2009
Location: Ontario, NY (PYC)
Posts: 161
Thanks: 5
Thanked 0 Times in 0 Posts
Rep Power: 6
cghubbell is on a distinguished road
Quote:
Originally Posted by CarelessNavigator View Post
Electrically they are the same. Electrons cannot tell the difference one way or the other. Just make sure the size/gauge of the wire is the same or able to handle the batteries you have. Two terminals on one wire = heavier wire gauge. One terminal and cable for each = lighter gauge wire. Most setups I have seen usually put the two terminals on one wire/cable.
I knew it was essentially the same in an electron's world (assuming proper wire gauges as you metioned). I thought there may be a difference in terms of some safety scenario, or just a best practice / ABYC rule that tends to be used. It surprised me that I didn't find anything specific in some of the books since everything else is so specific.

Thanks,
Chris
__________________
CS27 #1254 ~ Ravat
PYC, Lake Ontario

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote Share with Facebook
  #4  
Old 04-11-2010
nickmerc's Avatar
Senior Member
 
Join Date: Nov 2008
Location: O'Fallon, MO
Posts: 563
Thanks: 0
Thanked 1 Time in 1 Post
Rep Power: 6
nickmerc is on a distinguished road
When you are connecting batteries and components you want to make sure to use a "star pattern" for the ground wires. What this means is that each battery/device has only one path to ground. If not ground loops can be created and cause all kinds of gremlins. You can daisy chain components, just make sure only one end of the daisy chain is connected to the common ground point.

I like to use ground buses in areas where there are multiple components (radio panel, cabin lights and fans). I then run one wire from the bus to my main ground point.
________
Glass Pipe Pictures

Last edited by nickmerc; 08-18-2011 at 06:25 AM.
Reply With Quote Share with Facebook
  #5  
Old 04-11-2010
Maine Sail's Avatar
Senior Member
 
Join Date: Jan 2003
Location: Maine Coast
Posts: 5,412
Thanks: 11
Thanked 125 Times in 93 Posts
Rep Power: 15
Maine Sail is just really nice Maine Sail is just really nice Maine Sail is just really nice Maine Sail is just really nice
The real concern is to be sure you have only ONE common ground point to the earth. This is usually the engine. You can tie it all into a common buss then from the buss to the engine or ships ground. What you want to avoid is the use of multiple grounds to earth throughout the boat.

Using one ground wire for the batts is fine, and less expensive, but as others have noted make sure it is of a large enough gauge to support the entire system.
__________________
______
-Maine Sail / CS-36T


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.




© Images In Posts Property of Compass Marine Inc.


Reply With Quote Share with Facebook
  #6  
Old 04-11-2010
Senior Member
 
Join Date: Mar 2008
Posts: 886
Thanks: 0
Thanked 1 Time in 1 Post
Rep Power: 7
GaryHLucas is on a distinguished road
If you are redoing the wiring I would take each bank of batteries separately to the ground bar. That reduces the number of connections between any load and any battery. When (not if) you have an electrical problem, troubleshooting will be much easier too. If you aren't an expert in wiring it will also keep you from creating inadvertent ground loops that can drive you nuts. When loads share a common path then one load does affect another, with respect to electrical noise and voltage fluctuations. So a single large ground point has many advantages.

Gary H. Lucas
Reply With Quote Share with Facebook
  #7  
Old 04-11-2010
hellosailor's Avatar
Plausible Deniability
 
Join Date: Apr 2006
Posts: 10,711
Thanks: 2
Thanked 93 Times in 91 Posts
Rep Power: 10
hellosailor has a spectacular aura about hellosailor has a spectacular aura about
Aside from ONE common ground point...You also want the shortest possible cable run form the batteries to ground, with the fewest splices/lugs in it. And, if you ever are using the batteries in "combined" mode, in theory you want the cable runs to both batteries being equal. Identical cables, each from one battery to the common ground point, would do that best. Installing a ground bus (bar) or similar at that point would be a good way to ensure that everything else can be joined up to "the same" point, while still not glomming them all on one terminal.
Reply With Quote Share with Facebook
  #8  
Old 04-11-2010
mitiempo's Avatar
Senior Member
 
Join Date: Sep 2008
Location: Victoria B.C. Canada
Posts: 7,154
Thanks: 0
Thanked 71 Times in 62 Posts
Rep Power: 8
mitiempo will become famous soon enough mitiempo will become famous soon enough
I would try not to have more than one connection on each battery post. Negatives from each battery to a big bus, from the bus to the single engine ground point. Same for positives, one connection on each post, to switch and to a bus before the panel.
Attached Thumbnails
Battery grounds: Individual or common?-1.jpg  
__________________
Brian
Living aboard in Victoria Harbour
Reply With Quote Share with Facebook
  #9  
Old 04-11-2010
cghubbell's Avatar
1977 CS27 ~ Ravat
 
Join Date: May 2009
Location: Ontario, NY (PYC)
Posts: 161
Thanks: 5
Thanked 0 Times in 0 Posts
Rep Power: 6
cghubbell is on a distinguished road
Ok. I'll install a ground bus very near the battery boxes, give each battery its own wire to the bus, then take that bus to the engine grounding lug. Sounds like a plan. Thanks for all the responses!
__________________
CS27 #1254 ~ Ravat
PYC, Lake Ontario

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote Share with Facebook
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Battery Bank Design Kevin Jeffrey Gear and Maintenance Articles 0 05-12-2003 08:00 PM
Battery Bank Design Kevin Jeffrey Cruising Articles 0 05-12-2003 08:00 PM
Installing a New Battery Bank Sue & Larry Gear and Maintenance Articles 0 09-26-2002 08:00 PM
Boat Battery Power East Penn Manufr. Gear and Maintenance Articles 0 01-18-1999 07:00 PM


All times are GMT -4. The time now is 06:11 PM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.