Cruisers Forum
 


Join CruisersForum Today

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 17-01-2020, 15:56   #1
Registered User
 
japawil's Avatar

Join Date: Apr 2017
Location: Southern CA
Boat: Alajuela 33
Posts: 9
3 battery bank; how far apart?

I currently have a 2 battery house bank (group 31) on the port side of the engine and a starter battery on the starboard side. Iím looking to add another battery to the house bank.
There is basically no room to expand for another battery on the port side, but there is room for another battery on the starboard side.
What would be the consequences of having a 3rd battery say a 6/7ft cable length away from the other 2 as part of the same bank?
__________________

japawil is offline   Reply With Quote
Old 17-01-2020, 16:03   #2
Registered User

Join Date: Sep 2018
Location: Maryland
Boat: 1985 Ericson 32-3
Posts: 249
Re: 3 battery bank; how far apart?

Assuming you are like most in not regularly running high C charge or discharge on the house bank, there'd be no problem by connecting with heavy enough cable.
__________________

Checkswrecks is offline   Reply With Quote
Old 17-01-2020, 16:04   #3
cruiser

Join Date: Jan 2017
Boat: Retired from CF
Posts: 13,304
Re: 3 battery bank; how far apart?

Are we talking paralleling 12V units?

Not ideal, imbalance issues will reduce lifespan.

But not a critical issue, use nice fat wiring
john61ct is offline   Reply With Quote
Old 17-01-2020, 16:06   #4
Registered User

Join Date: Oct 2015
Posts: 1,833
Re: 3 battery bank; how far apart?

Quote:
Originally Posted by japawil View Post
I currently have a 2 battery house bank (group 31) on the port side of the engine and a starter battery on the starboard side. Iím looking to add another battery to the house bank.
There is basically no room to expand for another battery on the port side, but there is room for another battery on the starboard side.
What would be the consequences of having a 3rd battery say a 6/7ft cable length away from the other 2 as part of the same bank?
Making a parallel battery bank isn't quite as simple as it looks at first glance, especially if charging or discharging at high currents. The small, but non-zero resistance of batteries and cables can cause significant problems with keeping charges equal across the bank.

You'll find some reasons and data and solutions here:
https://fetchinketch.net/boat_though...y-connections/
billknny is offline   Reply With Quote
Old 17-01-2020, 16:34   #5
Registered User

Join Date: Jan 2014
Location: Panama City FL
Boat: Island Packet 32 Keel/CB
Posts: 513
Re: 3 battery bank; how far apart?

I have 6- 6V GC2, 4 midship and 2 in the fwd bilge, normally all 3 sets in parallel. Connecting wiring #4 AWG maybe 30 ft round trip (+ fused on both ends). Fwd bank is tapped directly to run bow thruster (330 Amps), anchor windlass (75 Amps). Start 3GM from the main bank. Been running that way for 14 years and if it has created any significant problems I haven't noticed.


Frankly
Frankly is offline   Reply With Quote
Old 17-01-2020, 16:39   #6
Registered User
 
Stu Jackson's Avatar

Join Date: Jan 2011
Location: Cowichan Bay, BC (Maple Bay Marina)
Posts: 7,965
Re: 3 battery bank; how far apart?

I have 3 Grp 31s, two forward about 6 feet from the third. I used proper sized wiring between them and used the run-through wiring (+ / -) as recommended by the right stuff guys. Been working fine for 22 years. Not an issue if wired properly.
__________________
Stu Jackson
Catalina 34 #224 (1986) C34IA Secretary
Cowichan Bay, BC, (Maple Bay Marina) SR/FK, M25, Rocna 10 (22#) (NZ model)
Stu Jackson is offline   Reply With Quote
Old 17-01-2020, 17:01   #7
Registered User
 
Cheechako's Avatar

Join Date: Aug 2006
Location: Skagit City, WA
Posts: 21,969
Re: 3 battery bank; how far apart?

It will work fine. Forget all the theories. That's all about micro effects to the user. Just use big enough cable.
__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard











Cheechako is offline   Reply With Quote
Old 17-01-2020, 19:05   #8
Registered User
 
japawil's Avatar

Join Date: Apr 2017
Location: Southern CA
Boat: Alajuela 33
Posts: 9
Re: 3 battery bank; how far apart?

Thanks for the replies.
Billkinny, thatís what I had in the back of my mind when I asked the question. I guess the easiest/best thing would be to put a couple terminal posts in the engine compartment and feed the batteries equidistance from there to give me the best bet at maintaining equalization.
The house bank is currently at the farthest run of the cables, so I wouldnít need to buy any more cable than I would have to connect to the opposite side of the compartment anyway!
japawil is offline   Reply With Quote
Old 18-01-2020, 11:17   #9
Registered User

Join Date: Jan 2016
Location: Portsmouth, UK
Boat: Westerly Conway 36ft
Posts: 161
Re: 3 battery bank; how far apart?

I found this article useful on this subject:
SmartGauge Electronics - Interconnecting multiple batteries to form one larger bank

about connecting batteries so they are balanced. Might be of help to you?
Clivevon is offline   Reply With Quote
Old 18-01-2020, 11:26   #10
Registered User

Join Date: Jan 2016
Location: Portsmouth, UK
Boat: Westerly Conway 36ft
Posts: 161
Re: 3 battery bank; how far apart?

Or as a simpler alternative, as there isnt room for a third battery there, is there room instead to put 2 larger house batteries on the port side to get some extra capacity?

The problem with unbalanced battery connections meaning batteries possibly failing at different times is that I have always understood it is best to replace all house batteries together so the older ones dont pull down the new one? Balancing the battery banks helps to extend overall battery bank life in that situation.
Clivevon is offline   Reply With Quote
Old 18-01-2020, 12:33   #11
cruiser

Join Date: Jan 2017
Boat: Retired from CF
Posts: 13,304
Re: 3 battery bank; how far apart?

less of an issue with parallel than serial

fine points for ideal longevity vs good enough adapting to what needs must
__________________

john61ct 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
Anti-fouling: why are these quotes so far apart? Gary Dean Construction, Maintenance & Refit 8 06-08-2018 04:44
In a galaxy (marina??) far, far, away.... jimp1234 Monohull Sailboats 1 18-04-2018 11:55
AC temperature sensor - how far is too far? Ostinato Construction, Maintenance & Refit 18 15-12-2015 14:20

Advertise Here


All times are GMT -7. The time now is 05:52.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.