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18-06-2018, 04:53
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#1
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Registered User
Join Date: Jun 2017
Boat: 1980 freedom 33 and 2005 hunter 41
Posts: 39
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1/0 or 2/0 battery interconnections
I am going to install 4 trojan 6 volts 400 amps at 20 hr rate, L 16, shoud i go with wich cable size?
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18-06-2018, 06:03
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#2
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Moderator Emeritus
Join Date: Oct 2013
Location: Jacksonville/ out cruising
Boat: Island Packet 38
Posts: 31,351
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1/0 or 2/0 battery interconnections
The bigger the better, or said another way, you can only be too small.
Really depends on if you expect starting loads, windlass, big inverter etc.
Smallish charger and low level loads only and even 10ga would work.
However I’d go big, cause you don’t know for sure what the future holds.
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18-06-2018, 06:24
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#3
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Registered User
Join Date: Jan 2014
Location: Panama City FL
Boat: Island Packet 32 Keel/CB
Posts: 995
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Re: 1/0 or 2/0 battery interconnections
When you are into cables that size handling/ bending can become a PITA. Unless some strange arrangement, I would go with no bigger than 1/0. If you want to reduce vour connection resistance use crimped on battery post clamps (assuming L16s come with a post). I used #1 for what it is worth.
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18-06-2018, 06:45
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#4
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Senior Cruiser
Join Date: Jun 2009
Location: South Carolina, US
Boat: Valiant 42CE
Posts: 215
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Re: 1/0 or 2/0 battery interconnections
Really depends on what amps you plan to draw and round-trip distance from bank to load. We have 840Ah and use 4/0.
This ABYC table should help you (courtesy of Genuidealz.com):
Voltage Drop Calculator Genuinedealz.com
And don't forget to fuse your bank w/in 7" of the + post.
__________________
Regards,
Ted A
V42 #186 s/v Little Wing
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18-06-2018, 07:07
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#5
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Registered User
Join Date: Oct 2015
Posts: 2,007
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Re: 1/0 or 2/0 battery interconnections
Quote:
Originally Posted by captprogreso
I am going to install 4 trojan 6 volts 400 amps at 20 hr rate, L 16, shoud i go with wich cable size?
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The size of the battery itself is not really what matters here. What matters is the maximum amperage you are going to pull out of the batteries, or push into them during charging. Anybody who doesn't ask you what you maximum current draw is can't give you a correct answer. Whatever size you select, be sure you select a fuse for the system to match the wire size.
If you have a battery bank of 800 amp hours, I assume you have 200 amps of charging capability. 200 amps really NEEDS 2/0 wire by any reasonable standard. I would use 4/0 for battery interconnection where low resistance really matters.
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18-06-2018, 07:36
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#6
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cruiser
Join Date: Jan 2017
Boat: Retired from CF
Posts: 13,317
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Re: 1/0 or 2/0 battery interconnections
If you are really making use of a big bank, stands to reason currents will be high.
The Blue Sea Circuit Wizard app is the best way to gauge wire size, once maximum currents are known.
When in doubt round up.
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18-06-2018, 08:33
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#7
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Registered User
Join Date: May 2008
Location: Nova Scotia until Spring 2021
Boat: Custom 41' Steel Pilothouse Cutter
Posts: 4,976
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Re: 1/0 or 2/0 battery interconnections
Quote:
Originally Posted by a64pilot
The bigger the better, or said another way, you can only be too small.
Really depends on if you expect starting loads, windlass, big inverter etc.
Smallish charger and low level loads only and even 10ga would work.
However I’d go big, cause you don’t know for sure what the future holds.
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I have six L-16s. I went with 4/0 ga. to the charger (manufacturer's recommendations) and with 2/0 ga. as interconnection cables. Note that all these cables are the same length. Since this was posted, I've gone to a larger Victron charger/inverter, but the cables are the same: https://alchemy2009.blogspot.com/201...wering-up.html
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18-06-2018, 08:36
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#8
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Registered User
Join Date: Jan 2014
Location: Panama City FL
Boat: Island Packet 32 Keel/CB
Posts: 995
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Re: 1/0 or 2/0 battery interconnections
Based on 12 Volts
Voltage drop for 10ft 1/0 at 100 amps is 99 mv or .8%
Voltage drop for 10ft 2/0 at 100 amps is 77 mv or .6%
Voltage drop of two, new, fully charged, Trojan L16 in series from battery internal resistance at 100 amps is 340 mv or 2.8%
The drop in the batteries is same even if electrically connected together with railroad rails.
If I punched the right buttons on my old HP32S.
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18-06-2018, 09:18
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#9
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cruiser
Join Date: May 2011
Boat: Hitchhiker, Catamaran, 40'
Posts: 1,827
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Re: 1/0 or 2/0 battery interconnections
I had bad luck with L16's, as have others on this forum. They are made for floor buffers. You might reconsider if it is not too late...
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18-06-2018, 09:40
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#10
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Registered User
Join Date: Aug 2006
Location: Skagit City, WA
Posts: 25,453
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Re: 1/0 or 2/0 battery interconnections
The maximum amps you draw or charge are key. Too big a cable does not bend well for short interconnects if you cant do them straight! If they bend sharply, bend before you cut the cable, maintain the bend while putting the fitting on the end. On an 8-10" cable, bent sharply, the outside strands will be maybe a full 1/2" shorter or so when bent! The heavier the cable, the worse this is.
__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard
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18-06-2018, 14:01
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#11
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Registered User
Join Date: Feb 2016
Location: Edmonds WA USA
Boat: Island Packet, 40
Posts: 68
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Re: 1/0 or 2/0 battery interconnections
Quote:
Originally Posted by Thumbs Up
I had bad luck with L16's, as have others on this forum. They are made for floor buffers. You might reconsider if it is not too late...
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L16 Deep Cycle are batteries designed for heavy use and discharge. Personally I have had excellent results with my 30 yr old IP40 using 6 x L16s in series/parallel configuration. I used 2/0 for interconnection but you could use 1/0. The thing to remember is not so much the size of the cable but the size and length of the cable. It is total resistance that will affect the end result. you want as little resistance in the system as possible. The distance between interconnections of the batteries is small so the resistance added will be small. Still it is the total resistance you are concerned about so to be on the safe side use the heaviest you can logically use. The connections are mostly straight if the batteries are side by side.
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18-06-2018, 17:01
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#12
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Registered User
Join Date: May 2018
Posts: 14
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Re: 1/0 or 2/0 battery interconnections
As a Master electrician I’m pretty sure bigger is better. Unless you are saving money. It worth it to use a larger cm. Voyage drop and related heat can be minimized. GO FOR IT!!
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19-06-2018, 07:38
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#13
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Registered User
Join Date: Jul 2012
Boat: Lafitte 44
Posts: 180
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Re: 1/0 or 2/0 battery interconnections
What is the perceived problem with the trojan L16 battery?
Just working through the process of upgrading capacity by changing from two 8D's to an L16 or T105 based battery bank. Either will require modification of battery boxes to increase from 480 ish to 850 is amps at 20 hour rate.
All else being equal will go with the least painful modification and the fewest batteries ( advantage L16 ).
If L16 a potential problem would appreciate the heads up.
Tom
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19-06-2018, 07:47
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#14
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Moderator Emeritus
Join Date: Oct 2013
Location: Jacksonville/ out cruising
Boat: Island Packet 38
Posts: 31,351
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Re: 1/0 or 2/0 battery interconnections
I thought the Trojan flooded batteries and in particular the L16 are excellent batteries?
I have heard nothing bad about the L16’s?
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19-06-2018, 07:50
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#15
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cruiser
Join Date: Jan 2017
Boat: Retired from CF
Posts: 13,317
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Re: 1/0 or 2/0 battery interconnections
AFAIC they're fine.
But if I had to mod my boat to fit a new form factor in the NA market, I would make sure that my setup accommodated all GC2 sizes (includes plain GC) from
Duracell / Deka (EPM)
Trojan
Rolls / Surrette
Crown
US Battery
Superior
That way I would rest easy I'd never need to do the mod over again, and could buy great-value batts at reasonable prices pretty much anywhere in the world.
The other consideration is as I get older I can still handle them without hiring help.
Plus going past 2-3 paralleled strings starts to mean balancing issues, shorter lifespans.
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