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Old 01-06-2012, 02:32   #1
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Battery Cabling for Parallel Bank

Hi guys,

There is a lot in the forums on batteries and parallel banks but I can't quite find what I'm after.

Some time ago, someone in CF recommended me to a web site that gave a really good way of wiring up Parallel batteries for a house bank. It involved each positive side having one long and one short cable, and the same with negative. It was supposedly the best way to wire up a bank that made each battery equal.

I have made a new battery box for my girl and it has six 200ah batteries. Does anyone have an idea of what I might be recalling. I'd really like to connect them in the way that bests conserves and maintains them equally.. Afterall they are worth almost $300 each.

Regards Ted.
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Old 01-06-2012, 02:49   #2
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Re: Battery cabling for parallel bank

For two batteries. the idea is the positive feed to the main battery switch comes from 1 battery and the negative lead to the main bettery switch comes from the second battery.

This minimises the voltage drop difference between the two batteries.

For 6 batteries it's more complicated.

Edit

Wiring as above for 6 batteries should still give an even voltage drop.
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Old 01-06-2012, 04:30   #3
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Re: Battery cabling for parallel bank

Quote:
Originally Posted by noelex 77 View Post
For two batteries. the idea is the positive feed to the main battery switch comes from 1 battery and the negative lead to the main bettery switch comes from the second battery.
This minimises the voltage drop difference between the two batteries...
Indeed.
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Old 01-06-2012, 04:31   #4
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Re: Battery cabling for parallel bank

Quote:
Originally Posted by noelex 77 View Post
For two batteries. the idea is the positive feed to the main battery switch comes from 1 battery and the negative lead to the main bettery switch comes from the second battery.

This minimises the voltage drop difference between the two batteries.

For 6 batteries it's more complicated.

Edit

Wiring as above for 6 batteries should still give an even voltage drop.

--to the Negative buss bar?
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Old 01-06-2012, 04:35   #5
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Re: Battery cabling for parallel bank

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--to the Negative buss bar?
Yes to the negative bus bar ( for the negative) if you only have single pole battery switches.
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Old 01-06-2012, 04:58   #6
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Re: Battery cabling for parallel bank

Ted
You didn't say whether you have 6-volt or 12-volt batteries and whether your boat system is 12-volt or 24-volt.
If you have six 12-volt batteries and your system is 12-volt, the GordMay's diagram is what you should follow. But if you have 6-volt batteries and a 12-volt system (as I do), it gets more compl;icated. You have to wire each pair of batteries in series to give you the equivalent of three 12-volt 200ah batteries and then wire the three pairs in parallel to give you 600ah 12-volt house service.
There should be diagrams of this on-line but will take a picture of my setup and post it when I get back from my boat
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Old 01-06-2012, 05:04   #7
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Re: Battery cabling for parallel bank

Ted,

This is a good read and explains why its worth doing it right:

SmartGauge Electronics - Interconnecting multiple batteries to form one larger bank

Pete
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Old 01-06-2012, 08:36   #8
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Re: Battery Cabling for Parallel Bank

It really makes no difference.

Even if the individual battery loads are different during high current charge or discharge, within seconds of removing the current, battery to battery flow will equalize the charges.

As short and heavy as battery links are, even under CCA loads you are looking at millivolts of difference. Just differences in battery conditon will be an order of magnitude bigger. Do the math, its overkill about nothing. Put the cables where overall length is minimized.
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Old 02-06-2012, 01:21   #9
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Re: Battery cabling for parallel bank

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Originally Posted by bloodhunter View Post
Ted
You didn't say whether you have 6-volt or 12-volt batteries and whether your boat system is 12-volt or 24-volt.
I have six 12v house batteries.. sorry.
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Old 02-06-2012, 01:22   #10
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Re: Battery cabling for parallel bank

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Originally Posted by Pete7 View Post
Ted,

This is a good read and explains why its worth doing it right:

SmartGauge Electronics - Interconnecting multiple batteries to form one larger bank

Pete
This is exactly what I was looking for that someone directed me to earlier in the year. Now, my question is, how to wire up six house batteries that follow's this idea?
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Old 02-06-2012, 01:25   #11
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Re: Battery Cabling for Parallel Bank

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It really makes no difference.

Even if the individual battery loads are different during high current charge or discharge, within seconds of removing the current, battery to battery flow will equalize the charges.

As short and heavy as battery links are, even under CCA loads you are looking at millivolts of difference. Just differences in battery conditon will be an order of magnitude bigger. Do the math, its overkill about nothing. Put the cables where overall length is minimized.
Hi Andina, thank you for your response. Have you seen the link that Pete7 left from Smart guages, they are suggesting 'amps' not milivolts and it seems it makes quite a difference. Now I'm a complete novice when it comes to batteries and power, all i know is that what comes from the batteries gives me power to run things and if you use to hook up to a fence to keep the kids out of the garden, it works really well too, so I'm quite interested in your response about the Smartgauge recommendations.

Ted
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Old 02-06-2012, 02:11   #12
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Re: Battery Cabling for Parallel Bank

Ted,

Use method 3 in Pete7's link. Even if it is not necessary it provides equal current flow for the batteries.

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Old 02-06-2012, 02:42   #13
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Re: Battery Cabling for Parallel Bank

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Ted,

Use method 3 in Pete7's link. Even if it is not necessary it provides equal current flow for the batteries.

I'm starting to favour that one Viking. The only thing that concerns me is that I have five cables (2 x 5 with post and neg) to put into some kind of battery post. So far I havn't been able to find anything that will take that much?
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Old 02-06-2012, 03:14   #14
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Re: Battery Cabling for Parallel Bank

Ted,

The Blue Sea Systems 2001 single power posts should be able to hold five 1/4" lugs. Or you could try to fabricate your own.

PowerPost High Amperage Cable Connectors - PN - Blue Sea Systems

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Old 02-06-2012, 03:19   #15
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Re: Battery Cabling for Parallel Bank

Quote:
Originally Posted by tedsherrin View Post
Hi Andina, thank you for your response. Have you seen the link that Pete7 left from Smart guages, they are suggesting 'amps' not milivolts and it seems it makes quite a difference. Now I'm a complete novice when it comes to batteries and power, all i know is that what comes from the batteries gives me power to run things and if you use to hook up to a fence to keep the kids out of the garden, it works really well too, so I'm quite interested in your response about the Smartgauge recommendations.

Ted
It does make a difference that is actually measurable over time. As one who owns both Midtronics and Argus battery analyzers I can and do measure differences on incorrectly vs. correctly wired banks nearly daily.

On "end connected" banks the battery opposite the connected one is in the best shape. The one at the "connected end" is always in the worst shape. Banks that are cross connected are far better balanced when tested at years 1, 2, 3, 4, 5, etc. etc... On hundreds and hundreds of banks these real world test results are repeatable and consistent. I am not talking about a n=1. Parallel banks connected to just one battery are worse off in terms of intrabank balance than batteries were the bank is cross connected and the loads are on opposite ends of the bank.

I have two batteries in my shop now that were way out of whack despite being in parallel for 4 years. The battery opposite the connection is still in "usable" condition. The connected battery is not. If this was the first time I'd seen this I'd shrug it off as two batteries one went bad but I see this consistnetly an the battery that is the "connected one", is in almost all situations with improper wiring, is in worse shape that the ones further down the parallel string..

I would challenge any of the other marine electrical guys who own good analyzers to start looking at and measuring this. It can be eye opening...

Also manufacturers like Trojan, Deka, Lifeline, Rolls etc. publish diagrams on proper connection.. I've yet to see a manufacturers diagram show an "end connection" on a parallel bank......
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