48v battery bank help !

[Justabhoy1967]

Hi folks, I wonder if someone could help me out with my battery bank build.
I bought 48 272ah batteries Lifepo. which I am planning to put together for a 48v bank.
I would love real simple explicit instructions in how to do this. You can;t over simplify this for me, so step by step instructions would be great. Any type of diagram or drawing would be nice also. I am planning to use a BMS. Do I need 3 ? or is there a way of only requiring 1.Any help would be really appreciated as I don't want to damage me or the batteries.

 

[Bubba1]

Do you have the batteries now?

 

[Justabhoy1967]

yes

 

[snoobler]

Don't do anything with the cells until you have a BMS.

Download, read, digest, re-read until you understand, if you don't understand, ask:

Top Balancing LiFePo4 Cells using a low cost benchtop power supply.

To get the paper, click on the orange at the top of this page. This is a tutorial with detailed steps on how I top-balance my LiFePO4 Cells using a low-cost benchtop power supply. To get the tutorial, click on the orange "Download" button...

diysolarforum.com

BMS depends on how much current you need. I see in other threads, you purchased 2X LV6548. That means you need 13000W of power.

13000W/48V = 271A DISCHARGE. The charge limit may be different, and you'll need to make sure it's sufficient.

You could choose to make 16 groups of 3 parallel cells and then string those 16 groups in series represented by the terminology 3P16S.

However, if a single cell dies, it is likely to take the parallel 2 with it, and you have NO redundancy. If you have a problem, you will have to take the entire system down and find the bad cell.

If you make 3 separate 16S batteries, each with their own BMS, and parallel them, you could get away with 150A per BMS. If you have a cell failure, it's obvious. You can just take that 16S battery out of the circuit and continue uninterrupted with 2/3 of your batteries functional.

 

[Justabhoy1967]

I have seen a 48 cell bank on youtube, and initially that would be my preference but I take your point about one bad cell causing problems for the whole bank. Is there any capacity difference between a 3p16s and 3 separate 16s batteries ? If I did 3 separate 16s batteries as you recommend, would I simple have them individually connected to a bus bar and the bus bar connected to the inverter ?

 

[snoobler]

I have seen a 48 cell bank on youtube, and initially that would be my preference but I take your point about one bad cell causing problems for the whole bank. Is there any capacity difference between a 3p16s and 3 separate 16s batteries ?

3P16S might have about 3% more as stronger cells paired with weaker cells mask their weakness. 16S3P, each cell is visible directly, and each of the 16S batteries would be limited by their weakest cell.

If I did 3 separate 16s batteries as you recommend, would I simple have them individually connected to a bus bar and the bus bar connected to the inverter ?

Yep.

 

[Justabhoy1967]

3P16S might have about 3% more as stronger cells paired with weaker cells mask their weakness. 16S3P, each cell is visible directly, and each of the 16S batteries would be limited by their weakest cell.



Yep.

thank you

 

[Justabhoy1967]

what make BMS would you recommend ?

 

[snoobler]

If 100A works, I recommend OverkillSolar, but 3X 100A puts you at 300A. That's okay, but it's a little too close for comfort as load likely won't be perfectly balanced.

No other recommendations. Here are multiple BMS threads with good info.

 

[houseofancients]

what make BMS would you recommend ?

i'd also looking into tge seplos bms's..
they are well made, and more importantly are able to directly with your mpp solar inverters using the pylontech protocol