Author Topic: Battery Bank Configuration Help  (Read 14354 times)

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macizoe

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Battery Bank Configuration Help
« on: September 13, 2009, 05:55:23 AM »
Hi.


I am building a battery bank for my solar panels.  I am going to use a Blue Sky Solar Boost 50DLI to charge the batteries from the solar panels and a Samlex 1500 watt inverter (w transfer switch) and need some help with a battery configuration and diagram.  I have 14 12V 108 Amp Hour Sun Extreme batteries.  The system will be running in 24V.


Any help is greatly appreciated!


Thank you.


Josh

« Last Edit: September 13, 2009, 05:55:23 AM by (unknown) »

madlabs

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Re: Battery Bank Configuration Help
« Reply #1 on: September 13, 2009, 08:53:06 AM »
Put the batteries in series in 2's. So, you should wind up with 7 pairs of batteries, each pair connected in series, positive to negative. The connect all the remainaing positives and negatives together.


+--+--+--+--+--+--+---

|  |  |  |  |  |  |

-  -  -  -  -  -  -

|  |  |  |  |  |  |   24V

+  +  +  +  +  +  +

|  |  |  |  |  |  |

----------------------


HTH


Jonathan

« Last Edit: September 13, 2009, 08:53:06 AM by madlabs »

ghurd

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Re: Battery Bank Configuration Help
« Reply #2 on: September 13, 2009, 09:07:58 AM »
The batteries will stay better balanced if the Positive is connected between pair #2 and 3.

And the Negative between pair #5 and 6.


G-

« Last Edit: September 13, 2009, 09:07:58 AM by ghurd »
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juddley

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Re: Battery Bank Configuration Help
« Reply #3 on: September 14, 2009, 02:40:23 PM »
Do you mean like this Ghurd??




« Last Edit: September 14, 2009, 02:40:23 PM by juddley »

scottsAI

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Re: Battery Bank Configuration Help
« Reply #4 on: September 14, 2009, 10:54:50 PM »
macizoe,


Wire in series / parallel as madlabs showed, yet take the power from the diagonals.


       +--+--+--+--+--+--+---  Plus

       |  |  |  |  |  |  |

       -  -  -  -  -  -  -

       |  |  |  |  |  |  |   24V

       +  +  +  +  +  +  +

       |  |  |  |  |  |  |

Neg ----------------------


By *matching the resistance to each battery* the whole battery will be charging/discharging together. ***This is important***


*Do NOT connect the middle taps to the other batteries.*

Voltage measurement of the center taps supports watching each battery to make sure its healthy!


Measure across each "battery" if under load or charging. Wiring voltage drops will make each battery different.


Have fun,

Scott.

« Last Edit: September 14, 2009, 10:54:50 PM by scottsAI »

ghurd

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Re: Battery Bank Configuration Help
« Reply #5 on: September 15, 2009, 07:23:44 AM »
Yes.

If the Pos is on one end, and Neg on the other end, the 4th pair gets less power.

Not much difference with 3 pairs of batteries.  It could be significant with 7 pairs.


Amanda explained it a few times and I missed it.  I finally understood when ULR re-explained it.  It still did not seem quite right, until paper and pencil proved it.

G-

« Last Edit: September 15, 2009, 07:23:44 AM by ghurd »
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Ungrounded Lightning Rod

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Re: Battery Bank Configuration Help
« Reply #6 on: September 15, 2009, 07:09:22 PM »
I hadn't considered getting a better approximation of balance by moving the taps in.  Thanks, ghurd.


Moving the taps out one notch will produce better balance (3 vs. 5 units of voltage drop variation) at a cost in efficiency (15...18 units vs. 8...13 units).  But kiddie-corner is worse (21...30, variation of 9) as is center (0...12, variation of 12).


Of course if you want to use more wire you can get it dead-even.

« Last Edit: September 15, 2009, 07:09:22 PM by Ungrounded Lightning Rod »

ghurd

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Re: Battery Bank Configuration Help
« Reply #7 on: September 15, 2009, 08:02:40 PM »
Thanks for re-explaining it so it would get through my thick head.


I am undecided if it is best to go for balance or efficiency.

The wind mode charging amps (here) would be low.  

Calculating this configuration for a 1000W windmill in this area is almost silly, and the loads (here) would play a larger part.


Attempt at a re-explain: If the wires are large enough for a 1000W windmill, and the mode charging power is 30W, then the effect is less while charging than while drawing 1000W.


As eloquent as always,

G-

« Last Edit: September 15, 2009, 08:02:40 PM by ghurd »
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juddley

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Re: Battery Bank Configuration Help
« Reply #8 on: September 16, 2009, 12:04:50 AM »
First, my apology to Josh (macizoe)for hijacking your thread. With Thanks to Ghurd and ULR for above clarifications. A neighbor has the exact setup as above drawing I posted and has the final wiring from a recommendation of the battery wholesaler.


Josh, I was not able to find "Sun Extreme" battery you mentioned but I had thought maybe you might have meant "Sun Extender" which is commonly sold in my area with Solar installs and is AGM type battery. If that is the case, be advised that how you configure your battery bank is even more critical. After 1 year of service and 2 failed batteries the dealer finally admitted he had undersized the interconnects and the better way to have installed would have been with all equal length jumpers interconnected to a positive and a negative bus bar as ULR suggested, this takes more wire, but would have saved a lot of aggravation. A combination of high peak demands and low charging amps has made equalizing the system batteries nearly impossible.


If you provide more details (usage, physical arrangement, distance between devices, etc.)there are many on this board who can give an exact recommendation for layout, wire sizes, fuses, etc. You stated you already have the batteries but if I understand correctly from what I have read on this board a fewer number of higher amp/hr strings is better than a greater number of lower amp/hr strings. I know from my limited experience any number of AGM batteries greater than 1 is hard to get equalized so how you interconnect becomes more important. Just my experience.


Judd

« Last Edit: September 16, 2009, 12:04:50 AM by juddley »

macizoe

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Re: Battery Bank Configuration Help
« Reply #9 on: September 27, 2009, 11:20:54 PM »
First of all - Thank you everyone!  I am still a little confused.


Sorry they are Sun Xtender 108 Amp Hour batteries - typed it worng


Judd - Is the diagram you posted with the leads going from the +5 and the - 10 going to the charge controller correct?  Also which leads would go to the inverter?


The power comes from the solar array (about 1kw) via #6 wire to the Solar Boost 50, then I am using #2 wire - all lengths going to each battery, are equal lengths (about 21 inches each)and was planing on connecting to the batteries like in your diagram, unless I should not......


The batteries will be used to power my living room (stereo, projector, tivo, dvd player, etc), so it is used a few hours each day (some more, some less).


Thank you again!


Josh

« Last Edit: September 27, 2009, 11:20:54 PM by macizoe »

juddley

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Re: Battery Bank Configuration Help
« Reply #10 on: September 28, 2009, 12:25:55 PM »
Hi Josh,

Your question...

"Judd - Is the diagram you posted with the leads going from the +5 and the - 10 going to the charge controller correct?"


Yes, the point at which you connect to the battery bank becomes critical because of the voltage drops in the individual interconnects. The +5 and -10 connection gives the best balance. The two most commonly used ways is (+1, -14 as advised by some manufacturers) and (+1 and -2 NOT a good idea). In the system I had drawn there was a Voltage differential of 2.8v across bats 13,14 when charge controller/inverter were connected to bats 1,2. This caused 2 batteries to fail prematurely as they never got fully charged and the system was not properly sized Panels/Storage/Wiring. This should not be a problem for you as the Panels, inverter, MPPT,& Wire Size you have selected are well matched. My stating the importance of this for you is the selection of AGM, which is much less maintenance but does not allow for easy "equalizing" as batteries age, get abused, etc. So where you connect is more important


Your Question:

"Also which leads would go to the inverter?"

As I have drawn above.... Red POS (+5) & Black NEG (-10) connect to both MPPT and inverter (parallel) I checked the manual for Samlex Inverter http://www.samlexamerica.com/customer_support/pdf/Manuals/ST_Series_Manual_Aug2009.pdf

With #2 wire the Positive line should have have a 100A fuse in series and no disconnect is needed for inverter as the Samlex already has one built in. Max distance from Battery Connection point to Inverter with #2 wire is 3-6 feet.


I tried to envision the physical placement of your batteries with 21" wire lengths. You must have a different layout. If as above the width is 26" W,  91"L, & 9" High (BCI Group 31). Can't do with 21" lengths as a "home run" for each 24v battery pair?? Can you give a better description of Physical placement?


Also, the MPPT manual:

http://www.blueskyenergyinc.com/uploads/pdf/Manual_BSE_SB50L.pdf

Shows two rather skimpy connection points to Batteries. Do you have some type of Terminal block / Bus for +24v? It is internally fused ..... but an external fuse might be a lot easier to get to... just a thought.


Judd

« Last Edit: September 28, 2009, 12:25:55 PM by juddley »

raincatcher

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Re: Battery Bank Configuration Help
« Reply #11 on: November 30, 2009, 07:52:29 PM »
Hi ghurd, is there a recomended way to wire up a bank like this 24v, ie safe sequence of connection etc, which is the last connetc etc, sorry I,m a newbie


cheers

« Last Edit: November 30, 2009, 07:52:29 PM by raincatcher »

ghurd

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Re: Battery Bank Configuration Help
« Reply #12 on: December 01, 2009, 06:15:37 AM »
Use common sense.  Such as do not construct the bank with a load, minimize the chances of shorting anything, etc.

Also anything that can minimize the chance of confusion is good.


I would start with all the negatives, then all the green connections, then all the positives.

G-

« Last Edit: December 01, 2009, 06:15:37 AM by ghurd »
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raincatcher

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Re: Battery Bank Configuration Help
« Reply #13 on: December 01, 2009, 09:42:40 PM »
thanks a plenty, I presume by load you mean connected to a device/load ? cheers pete
« Last Edit: December 01, 2009, 09:42:40 PM by raincatcher »

bandt1125

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Re: Battery Bank Configuration Help
« Reply #14 on: November 17, 2014, 03:13:21 PM »
I know this post is old but I just found it. I fourteen 6v 208ah batteries and am using them for a 12v system. I would like to use the in the way shown but I have a question. If the #5 positive and the #10 negative go to the charge controller and inverter where would the positive and negative from the solar source come into, at #9 positive and #6 negative.  My controller is a pwm and not a mppt cause i will be using both solar and wind if that will make a difference.

Mary B

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Re: Battery Bank Configuration Help
« Reply #15 on: November 17, 2014, 05:51:55 PM »
Charge and Load attach to the same point

Jaust

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Re: Battery Bank Configuration Help
« Reply #16 on: November 19, 2014, 04:27:20 PM »
Bandt1125, I have a similar setup in the cabin I recently bought. I have 12-6v 220 ah wired in series and parallel as a 12v system, no solar as of yet. I found this forum after I was getting reamed in another forum for even having a string that long in 12v in the first place. They said it so dangerous some people didn't even want to help or explain the problem with this setup. Hopefully you and I could get some advice on the safety or practicality of wiring in 12v instead of 24 or 48v. I use very little power in my cabin..... TV, dvd player and some lighting. I'm on the high end but I figured my power use is no more than 3Kwh hours a day and only on weekends. That would be my winter use because we spend most of our summer time outside and all my alliances are gas. I charge my batteries through my inverter with a Honda 3000 generator.

joestue

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Re: Battery Bank Configuration Help
« Reply #17 on: November 19, 2014, 06:55:22 PM »
Lead acid batteries typically have 30-40 times the amp hour rating for short circuit.
--on the order of 8000 amps for a 200 ah cell.

This means the battery impedance is .41 to .314 ohms divided by amp hours.
or 1.5 milliohms for a 220 ah cell.

you can then estimate the difference in currents according to the difference in ohms between the interconnect terminals.
My wife says I'm not just a different colored rubik's cube, i am a rubik's knot in a cage.

archerpalms

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Re: Battery Bank Configuration Help
« Reply #18 on: November 20, 2014, 10:35:29 PM »
Hi,

i am looking at getting 20 x 100 ah deep cycle batteries to replace 6 x 210ah batteries.
Any suggestions on the best way to wire them together? They will be incorporated into a 24V system.
I have figured i can 12 batteries on the top of a rack setup and 8 underneath them (as that is all my space will allow for) i also don't want to run wiring longer than i have to, or change the current wiring setup .
+ + + + (+ ) ( - )
- - - - - +

+ + + -
- - - +

I was thinking of configuring them is something like this configuration. the pos and neg go to the inverter.
sorry if it seems a bit basic but can't think of another way to type it here.

Mary B

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Re: Battery Bank Configuration Help
« Reply #19 on: November 21, 2014, 01:36:58 AM »
20 12 volt or 6 volt?

archerpalms

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Re: Battery Bank Configuration Help
« Reply #20 on: November 21, 2014, 03:08:21 AM »
20 x12 volt into a 24v system.

frackers

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Re: Battery Bank Configuration Help
« Reply #21 on: November 21, 2014, 05:35:48 AM »
Sounds like what I've been using the last 2 years (or is it 3 years!!).  About 900kw-hrs have passed through the batteries in that time.

This is the overall look of the bank
http://gilks.ath.cx/gallery/index.php/Wind/IMG_1314

Connected together with copper bar as effectively 2 giant 12v batteries in series.
http://gilks.ath.cx/gallery/index.php/Wind/IMG_1319

Closeup of the interconnect between the two halves.
http://gilks.ath.cx/gallery/index.php/Wind/IMG_1318

Note that I've not tried anything clever with where I feed in or out, its all off one end. I figure the resistance of the copper bar is low enough I really shouldn't have to worry about it ;)

Robin Down Under (Or Are You Up Over)

archerpalms

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Re: Battery Bank Configuration Help
« Reply #22 on: November 23, 2014, 06:33:02 PM »
Did you make the bar and connections yourself?

joestue

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Re: Battery Bank Configuration Help
« Reply #23 on: November 23, 2014, 08:58:28 PM »
Did you make the bar and connections yourself?
do an ebay search for scrap copper and you will be seriously disturbed by the amount of copper that has obviously been stolen and cut up into 1 foot sections, to fit in a flat rate usps box.
anyhow you can get lucky and find bar scrap.

or buy it from online metals at like, 9$ a pound.
My wife says I'm not just a different colored rubik's cube, i am a rubik's knot in a cage.

frackers

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Re: Battery Bank Configuration Help
« Reply #24 on: November 23, 2014, 09:13:50 PM »
Did you make the bar and connections yourself?

I bought a 4m length of 32x4.7mm (5mm nominal) strip. Can't remember how much it was but it was a lot less than the batteries. Cut into the required lengths, the 'U' shaped bit to interconnect was made with a vice and 4lb hammer and I had about 300mm left over when all done.

All bolts, nuts and washers are 8mm stainless.
Robin Down Under (Or Are You Up Over)