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Battery Balancing w/6, 12v 75aH agm in parallel

 
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well, like the title says, I have 6 new 12v AGM lead sealed batteries.  75aH each.  Going to wire in parallel.  

I have seen many wiring schematics but they usually show 2 or 4.  If they have more than that, it's usually a series parallel hybrid.

I understand that the + and - mains coming off the ends of the parallel battery bank need to be the same length, but what about the parallel wiring to balance 6 in parallel?

I get the concept, just not sure how to do with 6.

And also, what would be the biggest 0/0 and what would be the smallest gauge I would want to use for the parallel bank?  

Does the overall length of + and - between the batteries need to be the same exact amount of length too, or just the ones going to the inverter and load?

If I was guessing, I'd say I should use 2/0 gauge welding/automotive wire among the battery bank and maybe 8 gauge going to inverter and load on charge controller?

pv goes to 40a mppt renogy
battery bank as described
2000w pure sine inverter peak 4000w

I get the concept of the fuses and where to place them and what size, just need help with the 6, group 24 battery balancing configuration.  

any help is greatly appreciated!  cheers!

ryan
 
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Is the inverter for 12V or 24V?

 
Sebastian Köln
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Assuming it is a 12V inverter, I don't see a problem wiring them all in parallel.
I would probably also run a wire from each battery pole to the inverter to keep the cable size manageable. (AWG 10 instead of 000)
 
ryan hay
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12 volt, 2000w continuous, 4000w peak pure sine inverter

i know how to wire in parallel.  i want the batteries balanced, as in this diagram, but with 6 batteries


Screenshot_2020-04-27-balancedcharging-pdf.png
[Thumbnail for Screenshot_2020-04-27-balancedcharging-pdf.png]
 
ryan hay
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Sebastian Köln wrote:Assuming it is a 12V inverter, I don't see a problem wiring them all in parallel.
I would probably also run a wire from each battery pole to the inverter to keep the cable size manageable. (AWG 10 instead of 000)




yeah but im also going to the load on my charge controller to a fuse box for 12v applications + the inverter (straight off batteries)

 
ryan hay
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I mean I think I know how I would do it... just getting other input from y'all.  thanks!
 
Sebastian Köln
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Oh! Now I see what you mean. I don't think it is necessary. I'd do that if I was building a measuring device any every tiny difference would be relevant.

What you could do: (naming Batteries b1-b6): one wire: b1-b2-b3-b4-b5-b6-inverter, and the other inverter-1-2-3-4-5-6 .
 
ryan hay
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Sebastian Köln wrote:Oh! Now I see what you mean. I don't think it is necessary. I'd do that if I was building a measuring device any every tiny difference would be relevant.

What you could do: (naming Batteries b1-b6): one wire: b1-b2-b3-b4-b5-b6-inverter, and the other inverter-1-2-3-4-5-6 .



could make a huge difference as far as getting the most cycles out of my new battery bank.  check this out-

Screenshot_2020-04-27-balancedcharging-pdf.png
[Thumbnail for Screenshot_2020-04-27-balancedcharging-pdf.png]
 
Sebastian Köln
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Interesting… I did not consider that.

How about this?
3x2.png
[Thumbnail for 3x2.png]
 
pollinator
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Never thought about balanced charging before.  How does that work with a  series/parallel setup?
 
pollinator
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My experience would say make sure that the positive inverter cable goes to the battery on one end and the negative goes on the furthest battery from it. That is how we handle all parrallel strings and how the battery company I deal with suggests. I would make sure to rotate the batteries every 6 months since you cannot equalize...
 
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Hi Ryan,

Did you ever figure the wiring out? If my order goes through (it's the holidays after all) I will be expanding from 4 Renogy 100aH LifePo batteries to 6 to finish out my home backup setup.  I haven't had any issues with doing perfectly balanced charging on the 4 I have (see pic).
IMG_0660.JPG
[Thumbnail for IMG_0660.JPG]
 
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What I would like to understand is why you feel the need to stick with 12V.  To me, these many parallel connections are a hallmark of poor design.  Automatically, seeing a 4000W inverter, is a sign that you should be making better equipment choices.  To actually generate 4000W, you would need to pull 4000W/12V = 333amps out of your batteries.  What size wire are you connecting your batteries with?  Here is a chart displaying safe ampicity capacities of wire gauges.  The highest copper cable readily available can't handle that many amp safely.  

There is no good reason to stick with 12V for a residential instillation in today's day and age.  You'd get much better results and better performance going with either a 24V or 48V system, both of which I have implemented on my own homestead.  The higher voltage allows me to seemlessly power big-ticket items like an air-conditioner, power tools, and my 240V well pump.
Ampicity-chart-.PNG
[Thumbnail for Ampicity-chart-.PNG]
 
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