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Old 18-06-2018, 05:53   #1
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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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Old 18-06-2018, 07:03   #2
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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 Iíd go big, cause you donít know for sure what the future holds.
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Old 18-06-2018, 07:24   #3
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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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Old 18-06-2018, 07:45   #4
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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.
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Old 18-06-2018, 08:07   #5
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Re: 1/0 or 2/0 battery interconnections

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Originally Posted by captprogreso View Post
I am going to install 4 trojan 6 volts 400 amps at 20 hr rate, L 16, shoud i go with wich cable size?
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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Old 18-06-2018, 08:36   #6
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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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Old 18-06-2018, 09:33   #7
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Re: 1/0 or 2/0 battery interconnections

Quote:
Originally Posted by a64pilot View Post
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 Iíd go big, cause you donít know for sure what the future holds.

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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Old 18-06-2018, 09:36   #8
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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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Old 18-06-2018, 10:18   #9
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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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Old 18-06-2018, 10:40   #10
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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.
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Old 18-06-2018, 15:01   #11
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Re: 1/0 or 2/0 battery interconnections

Quote:
Originally Posted by Thumbs Up View Post
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...
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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Old 18-06-2018, 18:01   #12
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Re: 1/0 or 2/0 battery interconnections

As a Master electrician Iím 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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Old 19-06-2018, 08:38   #13
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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.
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Old 19-06-2018, 08:47   #14
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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 L16ís?
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Old 19-06-2018, 08:50   #15
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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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