Cell balancing importance

Question

question

inam asked 3 days ago

Cell balancing importance

Hi , Dear all,

I have a question regarding the lithium batteries cell balancing, if i have frequent charge discharge cycles as shown how cells are balanced? I have a 48 volt 100Ah batteries with 15 cells.

as shown there is very rapid charge and discharge cycles , will it provide the advertised cycle life.

graph is shown for a single day, does BMS balance the cells or there are some other circuitry.

further to add as the battery ages there is definitely variation in individual cell resistance /capacity , connections etc. what would the impacts ?

Lithium Battery

1721804650862.png (71.1 KiB)

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Modifications Space

Node Red Space

Answer 1 · 2024-07-24T11:09:12Z

klim8skeptic answered · 3 days ago

@Inam Your post has no details, and your graphs have no reference. A pointless, empty, nonsense post.

If you want to learn about Li batteries and cell balancing, you could spend a couple of hours looking at Victron's Lithium Smart Battery Manual.

Starting Here would be a good starting point. But read the appropriate sections.

3

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

inam commented · 3 days ago

thanks, I have read the relevant material as you mentioned, the document describes that cell balancing needs to be done at absorption stage for 2 hours, but i have given a real life example of battery current curve it charges and then discharges frequently , so I needed your expert opinion...

0 ·

klim8skeptic ♦ inam commented · 2 days ago

@Inam but i have given a real life example of battery current curve it charges and then discharges frequently

No. Your chart shows a charge / discharge of 15a, without any absorption time, or yhe charge current dropping down to an acceptable tail current.

To be considered fully charged, the battery charge current has to fall to 2-4% of the battery C rating.

And to be considered properly balanced, at the end of absorp, the cell voltages have to be similar.

0 ·

inam klim8skeptic ♦ commented · 2 days ago

Voltage and current graph is given below as you required , I had mentioned in the earlier post that there is unstable grid so overtime there would be difference in the cell voltages , i tried to ask the specific question

0 ·

1721823552909.png (88.3 KiB)

question