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AGM Pack Design
#1
Hi All,

I've been given 12 x 12v, 120AH AGMs. Wanting to use them with solar at the farm.


Just after some opinions on best way to configure them.

I have a 48v charger/inverter (PIP-5048MS) already. Pretty happy with it but open to getting another type if better suited for task.

I could hook them up like this but suspect there will be another way to help them balance better?

Developing a sustainable farm and homestead. East coast of Australia
AussieBush.Life
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#2
(04-17-2019, 03:53 AM)Spazmor Wrote: Hi All,

I've been given 12 x 12v, 120AH AGMs. Wanting to use them with solar at the farm

Just after some opinions on best way to configure them.

@Spazmore

Your configuration does not allow for a failure of any 1 of the batteries. You would have to disconnect the whole pack to replace any one of them. It also is not really optimal for balancing although Pb based systems don't require it so much. Nevertheless I do have a balancing system on my pack.
A better way of stringing the pack would be as following:

That way you can take one of the strings off line and service it while the other 2 are still working.

Balancing I accomplished with a self build Balancer setup with these modules. https://www.ebay.com/itm/1Pcs-48V-Solar-...23b3101458


And the bank with thermostatically and PWM controlled Server case fans.


Wolf
Spazmor likes this post
If 18 X 650 = 2200+mAh then we have power! 
May all your Cells have an IR of 75mΩ or less Smile
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#3
Connect the inverter to the positive pole of the top battery, and the negative to the bottom battery. That way the whole bank will balance a bit better.
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#4
(04-17-2019, 02:27 PM)SilverNodashi Wrote: Connect the inverter to the positive pole of the top battery, and the negative to the bottom battery. That way the whole bank will balance a bit better.

That is certainly a good way to try to keep the pack equal.
In my case I opted for Heavy duty Buss cabled between all the negative posts on one side and the same on the positive side and drawing from the middle, both feeds going to a buss bar where all items are collectively supplying and or drawing.
I do have a equalization setup though as discussed and my batteries will vary by a 10th of a Volt every now and then but not for very long.

Wolf
If 18 X 650 = 2200+mAh then we have power! 
May all your Cells have an IR of 75mΩ or less Smile
Last count as of 5/16/2019
Total Number of Cells                          5198
Cells  >80% of Capacity                      3675
Cells <80% of Capacity                       1483
Cells ≥2200mAh & ≥ 80% & ≤75mΩ    2539
For Info Google Drive
Not your average Wolf       
            Cool



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#5
(04-17-2019, 03:40 PM)Wolf Wrote:
(04-17-2019, 02:27 PM)SilverNodashi Wrote: Connect the inverter to the positive pole of the top battery, and the negative to the bottom battery. That way the whole bank will balance a bit better.

That is certainly a good way to try to keep the pack equal.
In my case I opted for Heavy duty Buss cabled between all the negative posts on one side and the same on the positive side and drawing from the middle, both feeds going to a buss bar where all items are collectively supplying and or drawing.
I do have a equalization setup though as discussed and my batteries will vary by a 10th of a Volt every now and then but not for very long.

Wolf
This is an even better way of doing it. But keep all the cables between the battery banks and the busbars the same length.
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#6
Thanks so much Wolf,

Your system looks beautiful. It's a bit fancy!
I agree with you that design looks like it would balance better and allow for redundancy too.
I like it alot..



Are those voltage LCDs accurate in this configuration? It hurts my head to try to understand if the other batteries will affect the readings.


Also, I know PB is forgiving but, do the 4 batteries within series become unbalanced?
I was looking at balancing at the battery level with 4 of these https://www.aliexpress.com/item/battery-...22608.html

Final question Smile if you don't mind, how have you joined the three packs where they combined onto the bus cables. What type of connection, crimps, terminal lugs with nut and bolt?
Developing a sustainable farm and homestead. East coast of Australia
AussieBush.Life
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#7
You generally balance la batteries by overcharcing Them. So as Long as you have the Charger correctly setup it Will work fine
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#8
(04-18-2019, 06:27 AM)Spazmor Wrote: Are those voltage LCDs accurate in this configuration? It hurts my head to try to understand if the other batteries will affect the readings.
Actually they are quite accurate at least to the tenth of a volt. I did check them before using them against a reference voltage generator.
The battery voltage that the LED voltmeters show comes from a direct connection to the pos and neg of each battery. I don't have a picture of it but I did have a battery fail and the voltage of that battery was so far off from the others it was easily found and replaced


Quote:Also, I know PB is forgiving but, do the 4 batteries within series become unbalanced?
There is a lot of information on that subject just look up AGM battery balancing and the results will educate you.
As daromer said
Quote:daromer
You generally balance la batteries by overcharcing Them. So as Long as you have the Charger correctly setup it Will work fine

Quote:I was looking at balancing at the battery level with 4 of these https://www.aliexpress.com/item/battery-...22608.html

I have that same style equalizer on my battery bank. Except I went anal and got three of them for 3 strings. I don't think that is necessary especially if you tie all the batteries together on the negatives as you see in my diagram.
Quote:Final question Smile if you don't mind, how have you joined the three packs where they combined onto the bus cables. What type of connection, crimps, terminal lugs with nut and bolt?
Post a picture of the AGM battery you got or the part number and lets see what is available for a 3 parallel setup or what can be made.
In my case the batteries have a regular post and a threaded post. The regular posts I joined with a cable similar to this but with regular post terminals.

The rest are all homemade cables with crimp terminals and AWG 2 Cable.
The beginning of the bank
 
There where many changes made between that picture and now.

One of them is tapping the bank from the center of the battery bus bars and equal cable lengths on the pos and neg of the bank to the main distribution bus bar.

Wolf
If 18 X 650 = 2200+mAh then we have power! 
May all your Cells have an IR of 75mΩ or less Smile
Last count as of 5/16/2019
Total Number of Cells                          5198
Cells  >80% of Capacity                      3675
Cells <80% of Capacity                       1483
Cells ≥2200mAh & ≥ 80% & ≤75mΩ    2539
For Info Google Drive
Not your average Wolf       
            Cool



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#9
These are the batteries I was given.
They're from a retired UPS. Old but didn't see much action so hopefully still have some useful life left in them. They've been holding a charge but I should do a capacity test on them.

I have some 4guage cable I was going to use. This should be ok at least between the batteries maybe x 2 for the bus cables? IDK is that's overkill. I'll likely have less than 1.5m bus cables.
Rated inverter power is 4.5kw / 48v = 94A
Developing a sustainable farm and homestead. East coast of Australia
AussieBush.Life
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#10
(04-23-2019, 10:59 AM)Spazmor Wrote: These are the batteries I was given.
They're from a retired UPS. Old but didn't see much action so hopefully still have some useful life left in them. They've been holding a charge but I should do a capacity test on them.

I have some 4guage cable I was going to use. This should be ok at least between the batteries maybe x 2 for the bus cables? IDK is that's overkill. I'll likely have less than 1.5m bus cables.
Rated inverter power is 4.5kw / 48v = 94A

I had an 100ah AGM battery that was over discharged. Was at about 7v for memory. I recharged it very very slowly, took about a month, so as not to 'boil' and dry it out. Came back at about 80ah or so. It's about 8 years old.

It will be interesting to see what sort of life you get out of them.
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