Connecting 4 x 6 Volt to make 12V Bank

[nigel1]

Considering that when the time comes, I will replace the 2 x 12V 180Ah batteries with 4 x 6V 225Ah batteries to make the house bank.

Trying to cut down on cable run lengths etc.
I have attached a proposed connection connection.
1) Will it work

2) Can it be improved on.

Note, the batteries them selves will need to sit in the box same as in the drawing, but can be turned through 180 degrees if it makes for a better set up. ie the posts can be at the opposite ends

[Dustymc]

Here's what I did:

SV Rhapsody: Electrical

You want the positive and negative leads coming from opposite "corners" rather than next to each other as you've sketched.

[sy_gilana]

yes, you can connect 2 in series twice. But if they are the Trojan T105 225AH they will not be that shape.
I have just done a catamaran's batteries with no fewer than 20 trojan T105's in groups of 4 in series five times.
I don't know of 6v batteries in the 8D shape.???

[nigel1]

Originally Posted by Dustymc

Here's what I did:

SV Rhapsody: Electrical

You want the positive and negative leads coming from opposite "corners" rather than next to each other as you've sketched.

Thanks for the quick reply Dusty, so, connect the Negative Cable to the negative post on Battery No. 1, rather than on Battery No. 4.

I did kind of suspect that someone would pick up on that. I had previoulsy been looking at this website
SmartGauge Electronics - Interconnecting multiple batteries to form one larger bank

but they did not quite cover my situation.
Cheers

[nigel1]

Originally Posted by sy_gilana

yes, you can connect 2 in series twice. But if they are the Trojan T105 225AH they will not be that shape.
I have just done a catamaran's batteries with no fewer than 20 trojan T105's in groups of 4 in series five times.
I don't know of 6v batteries in the 8D shape.???

Thanks, my error, was thinking of the posts on the original batteries.
Yes, they will be T105, and I see from the Trojan website that the posts are on diagonally oppostite corners

[Target9000]

[Target9000]

Sorry if the color key on the image is mixed up, I tried to fix it but the server doesn't seem to be refreshing, but anyway, you get the idea.

[nigel1]

Second attempt with the battery posts in the correct corners.

In this diagram, I have the series connections between batteries 1 and 3, and between 2 and 4.
The parallel conections are between the +ve posts on 1 and 2, and the
-ve posts on 3 and 4.
I think i have managed to take the +ve and -ve leads from opposite corners.

Do I need to parallel connect the -ve posts on 1 and 2 and the +ve posts on 3 and 4.
It was that when I looked at the pictures on Dusty's website, their appears to be more connecting cables than I have shown on the drawing

[Dustymc]

I do in fact have a couple "unnecessary" cables. That's a recommendation I believe from Caulder's book (which I don't have in front of me at the moment) - something about doing a better job of evenly (dis)charging the batteries, in conjunction with where the leads are placed.

My boat starts and my sink doesn't smoke, so that's something....

[nigel1]

Originally Posted by Target9000

Sorry if the color key on the image is mixed up, I tried to fix it but the server doesn't seem to be refreshing, but anyway, you get the idea.

Cheers, I got the picture, thanks very much, just need to swing my battery's around to get the same line up as in your drawing. Much neater.
Cheers again

[nigel1]

On a related subject, is there any particular order in which the cables should be connected with regard to safety. Should the series cables go on first, or the parallel ones, or does it not really matter

[Target9000]

Originally Posted by nigel1

Cheers, I got the picture, thanks very much, just need to swing my battery's around to get the same line up as in your drawing. Much neater.
Cheers again

Great! And good luck.

[nigel1]

Originally Posted by Dustymc

I do in fact have a couple "unnecessary" cables. That's a recommendation I believe from Caulder's book (which I don't have in front of me at the moment) - something about doing a better job of evenly (dis)charging the batteries, in conjunction with where the leads are placed.

My boat starts and my sink doesn't smoke, so that's something....

Thought it might have something to do with that, may your engine continue to start and your sink not smoke. I'll have to have a look at Calders book

[btrayfors]

Nigel,

Here you go:



The two short jumper cables are 6.0" long, hole-to-hole.

The two longer ones are less than 12" long.

Suggest you use AWG1/0 or larger for the jumpers.

Bill

[S/V Alchemy]

Bill, what do you think of the setup here (SmartGauge Electronics - Interconnecting multiple batteries to form one larger bank)



...where the emphasis seems to be on "battery balancing", a term I had not heard before except in terms of not mixing old and new or Group 31s with Group 27s.

The case seems to be concerned with the "compounding of resistance".

Does this actually make sense?

I ask because I want to make an 860 Ah house bank for extended cruising, and my choice is to "build it" from 4 x 8D 12 VDCs or the equivalent in Trojan T-105s.

Your comments would be appreciated. The "cumulative resistance" idea in this article is new to me, but makes a sort of sense when you consider voltage drop on longer, thin runs.