[nlc]

Good, now there are some concrete thing to discuss

I don't know how clear I can be about this: If you don't bottom balance your batteries you risk loosing the whole pack. When one battery goes dead at the bottom of it's capacity it takes all the others with it eventually.

Need more explanation, as I said if BMS do it's job, cells cannot be discharged under LVC or overcharged over HVC. If the BMS is malfunctioning on just one cell, only this cell can be damaged. If you are not agree, please explain how other cell can be destroyed ?

-First Bottom Balancing the cells is only done once in the life of the pack unless you add more cells to the pack in which case you want put all the cells at the same level from the bottom of their capacity.

This precision is really important, why you don't say that before ? Why compare a procedure which is done once (bottom balancing) and the top balancing which is eventually done each charge ?

-Second I never said completely discharge the cells. You said that which is wrong. I said and still do: 2.75 volts per cell to be safe. You bottom balance at that voltage NOT "0 volts".

Never talk about 0V, always talk about LVC

-Third I am sorry if I am blunt but I have been doing this since the 80's with radio controlled airplanes. When you loose an aircraft at 80mph over the people,s heads because of batteries failure you start investigating the reasons why.

I am not blunt I try to understood, but it's clear that there a misunderstanding, I understood that the bottom balancing you talked about and is discussed on some forum was a procedure to do every charge !!

-Fourth When you say and I quote: " it's exactly the opposite of the prefered method for lithium chemistry, charge them even if they are not empty, to increase their lifetime" you are speaking about preferences not facts. People preferred SUVs, war and politics and think they are safe yet the figures show the contrary.

Not fact ? Yet, I seen somewhere curve which show that a cell will give more Ah in its life if it is charged before it is completely discharged (at LVC I mean !)

-Fifth on the HVC side you are right you should cut off once the first cell reaches that state. Yet you'll be surprised what you find if you measure them individually 24hrs later.

It's normal each cell cannot be 100% identical (internal resistance, temperature, ...). But what does it change to the discussion ?

Do the test and verify my words.

Yes but test what ? What can be exactly be compared and tested ?

-Sixth and probably this is the most important since there is a danger factor. Cells will not take more energy than what their chemistry allows on HVC but will go downhill in a hurry if one goes through their nominal low bottom threshold. When that happens it happens in a steep curve. Look at the manufacturers specifications it's there.

Never said the contrary, and there is no relation with top/bottom balancing and this fact : the BMS must cut discharge when at least one cell reach the LVC.
But if it happens on one cell because the BMS LVC cutoff doesn't work on this cell, only this cell will be destroyed.

Last this is really a controversy and I am not here to antagonize but I am just looking at the facts take this blog for example I think you'll find it amusing how with the same facts they arrive to totally opposite conclusions:

If there is a controversy it's absurd because we talk about a procedure to do once....

Endless-sphere.com • View topic - Bottom balancing?

There is an endless discussion about how arrogant Jack Rickard is about this matters. Who cares? Basically people who care more about personalities than science. Yup he might arrogant but I think he is right. Furthermore I see he is right. And it is kinda convincing when you can see things don't ya?

I don't care about personality, if anyone tell something it must not be a affirmation but need argument and logical explanations. Only after that you can conclude.

So look at the graphs on that blog and tell me what you notice on the graph.
There's top balancing and bottom balancing. Now this is math. Numbers no bull. Tell me where the curve is flat and I'll tell you where you have the most average energy.

It seems you forgot to put the blog link ?