diy solar

diy solar

Help with 128 batteries each one is 280ah, and want to configure for 48v system.

I'm wondering if I should take those 4 down lower before putting it back together. Since pulling batteries from the bank I have not built yet exhibited the same issue? Few of the history logs taken from earlier need to pull todays.

It seems like the bulk of the batteries are stopping at 3.388 and the others are continuing to charge.

I orginally found a few links on diy that talked about soc can vary at the same voltage. and amazingly offgridgarage just did a video on this.
 

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I love this! Prior to me switching to Lifepo4 I was all set to expand my Nissan Leaf pack but the prices were crazy at the time for the cells - they became very popular for second life situations and Lifepo4 cells were under $100 shipped (280ah) so I made the decision to switch.

One of the inspiring studies and applications was done by UC Davis: http://mae.engr.ucdavis.edu/jwpark/DavisSite/pages/BWF-microgrid.html
 
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I love this! Prior to me switching to Lifepo4 I was all set to expand my Nissan Leaf pack but the prices were crazy at the time for the cells - they became very popular for second life situations and Lifepo4 cells were under $100 shipped (280ah) so I made the decision to switch.

One of the inspiring studies and applications was done by UC Davis: http://mae.engr.ucdavis.edu/jwpark/DavisSite/pages/BWF-microgrid.html
Thx for posting the study, I try and read that today.
 
Pulled one of the batteries that I charged to 3.388, I decided to just see how it performs. After being used sparingly during testing and I have not really pushed them the lowest discharge state was 52.41. It will finish in about 10+ hours.
 

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Results were low, 252ah, I stopped at 2.55 but this would not account for that much ah. I grabbed one from the other banks that I'm trying to complete that have only been top balanced and will test.
 
Output from the last test. Started charging the battery tested last night and charged up quickly till it hit 3.344. I remeber the orignal test and the batteries charged up quickly so I do not understand them stalling at 3.388 or at 3.344.

I stopped the charging and let battery sit, it dropped to 3.313. I would be open for any suggestion on the charging behavior. It seems the disharge test lowered what this one will charge to. The row this came from all charged to 3.388 yesterday but this one stalled at 3.344.
 

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The one that I had thought was stalled charged all the way to 3.650. I just do not remeber it taking so long before when you hit the 3.344 range but that was a lot lost sleep each night when I fully top balanced them. Here's another test completed, it does appear that video from off grid garage the soc can vary more than I thought.
 

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The one that I had thought was stalled charged all the way to 3.650. I just do not remeber it taking so long before when you hit the 3.344 range but that was a lot lost sleep each night when I fully top balanced them. Here's another test completed, it does appear that video from off grid garage the soc can vary more than I thought.
The one battery I tested/charged for capacity, when mine arrived, seem to take a long time to get from 3.3-ish to 3.65. I don’t remember exactly how long, but it seem to take forever. I did not write down the time on that initial test.
 
The one battery I tested/charged for capacity, when mine arrived, seem to take a long time to get from 3.3-ish to 3.65. I don’t remember exactly how long, but it seem to take forever. I did not write down the time on that initial test.
I was so tired back then, since it's all new and so much money invested, I was up every few hours. I try and take notes and remember it all just in case there are any changes in the system that could be abnormal. How are your batteries doing, are the meeting the description from the seller and capacity? Thanks for the feedback
 
I’m not capacity testing each cell (68, 4-extra ordered)
Currently parallel balancing the pack, should be finished today. Then compressing 4 packs of 16 to parallel top balancing. So far so good.
 
I add super capacitors between cells and 1e-7 resistors and solved the runner issue.
Wished I had the batrium when I was top balancing the first 128, working on the next
bank. Makes it nice to be able to watch instead of checking continuously.
 

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I add super capacitors between cells and 1e-7 resistors and solved the runner issue.
Can you share pictures and explain more? The picture you posted shows 14 being full or is that the next bank in process of top balancing with Batrium?
Wished I had the batrium when I was top balancing the first 128, working on the next
bank. Makes it nice to be able to watch instead of checking continuously.
So what are you top balancing with Batrium and inverter power or a bench power supply? Just curious if you using Batrium to monitor top balancing, assuming you’re using inverter....?
 
I add super capacitors between cells and 1e-7 resistors and solved the runner issue.
Wished I had the batrium when I was top balancing the first 128, working on the next
bank. Makes it nice to be able to watch instead of checking continuously.
@kromc5 maybe I missed it but what is your use case that you’ll need that much storage...?
 
Can you share pictures and explain more? The picture you posted shows 14 being full or is that the next bank in process of top balancing with Batrium?

So what are you top balancing with Batrium and inverter power or a bench power supply? Just curious if you using Batrium to monitor top balancing, assuming you’re using inverter....?
I have them arranged in banks of 4, and then just strung the batriums down the rows, I using TekPower TP1540E 0-15v to 40amp. So I'm just charging 4 at time, but I thought it would be easy just to pre-wire each batrium instead of moving one.
 
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