BMS Cell Balancing | Active cell balancing | Passive Cell Balancing | Battery Management System

Hi everyone!!

One of the major control algorithm of Battery Management System is Cell Balancing.
Cell balancing is the process of equalizing the voltages among individual cells. Each cell in battery pack has a different state of charge (SOC) and this changes with increase in number of charge-discharge cycles.
Battery Cell balancing is needed as each cell needs to be charged and discharged properly otherwise it can lead to thermal runaway and can cause catastrophic failures.

There are two techniques of cell balancing:
1. Passive Cell Balancing
2. Active Cell Balancing

Let us understand each technique along with the pros and cons of each.

Watch the video to find out more.

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[nagalakshminakka]

The way you are teaching is excellent.I think this is the best video in my studies

[akshaybose]

good presentation . thank you so much .

[engineeringinventor]

Thank you it's very knowledgeable video.❤❤❤

[mohamedabdelaal]

Thanks, do you have a book explaining these concepts?

[AkramIssahaku]

I am using DELL latitude e6530 it uses cylindrical battery cells of 5000 mah i want to upgrade it to use 20, 000mah lithium cell batteries (like the one used in powerbanks) Is it advisable for me to take this approach?

[Albertkallal]

Left out of this of course is for a ebike battery, the BMS does not address nor can it determine the individual state of each battery.
So, say you have a 48v ebike battery rated at 13ah. So, that setup is going to be 13 cells in series, and you have 5 sets of these 13 cells in parallel.
The BMS will thus have ONLY 13 wires, one to each "set" of 13 batteries. But the BMS thus can't tell individual voltage in each of those 13 cells, but only the overall voltage for the 13 cells.
There are a few BMS systems for ebikes that have a wire to EACH battery, but these systems are rather rare to be found.
Hence, the BMS can "try" to balance the set of 13 cells, but it in NO WAY can check nor balance each cell.
This means the BMS can only balance the 13 "sets" of batteries.
This thus means that in each set of 13 cells, they can become un-balanced, and individual cells can thus be overcharged, and some can be under charged.
So, while such a battery pack will have a total of 65 cells, the BMS can only deal with, and try to balance 13 cells "together" at one time.

Thus, this video fails to address how battery balancing works in 99% of the ebike batteries on the market right now.
Individual cells in a ebike battery thus are not balanced by the BMS, but only a set of 13 batteries together are balanced, and you "hope" that this is good enough....
Kind of leaving out the elephant in the room, don't you think?

[mahamayabose]

Both the active and passive balancing system fails in LiFePO4 battery packs. They work fairly in Li-ion and Li-Po battery packs. Any suggestions to balance LiFePO4 battery packs?

[ganeshpatnam]

how to find individual failure cell while connected in lithium battery pack

[Spdgt]

Is there any differents when balance cell pin during chagring two cases? Case1: chagring from 20% to 100%. Case2: chagring from 80% to 100%. Which case give the better result? Thank you

[MaNMega]

Hmm my textbook says that active balancing can discharge the battery and passive charging doesn't discharge the battery. The opposite of what this video says?

[JitendraKumar-gxri]

Hamare lithium battery mein balance bigad Gaya balance theek karne ke liye cell discharge karke fir recharge kar le to theek ho jaega

[manologodino]

video looks interesting but I didn't get your pronunciation.

[alexandres]

for nimh hybrid battery low voltage cells pasive balacing is the better option.

[LarryP]

This content is abundant with enlightening ideas. Reading a book with similar themes influenced my life's direction. "A Life Unplugged: Reclaiming Reality in a Digital Age" by Theodore Blaze