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EV6: Is this a good thing to do to maximise long term battery life?

14K views 32 replies 16 participants last post by  X4dow 
Modern battery management systems can balance cells at less than 100%/max voltage, I don’t know why people keep saying it.

Especially when they often also say that 100% isn’t 100% due to battery buffers. How can you charge to 100% when you can’t?!

Just charge it and use it how you need to, let the BMS do its job is my totally free ‘advice’. ;)
 
Yes it can, but it'll not balance when it's below its defined 100% SoC. The Kia Connect app even has an indicator on the status screen that indicates 'balancing'. The battery icon will blink or something like that. You can also check what's happening once 100% is reached. You'll see the charging voltage drop since at that moment the BMS starts balancing the cells and will try to bring the lower ones up to the voltage of the higher cells. This process may take a couple of minutes or an hour, depends on the state.

Another indicator that it does not balance throughout the charge is that once cells are un-balanced (check via an ODBC reader), they will remain unbalanced until you charge to 100%
That’s a conscious choice by Kia, which is fine, but just confirms my point that a BMS can balance individual cells at less than 100%.

I get that Kia call it 100% for ease of understanding by customers, when it’s actually 90% in reality.
 
I think this is true for Leafs and Zoes.

However more modern BMS can balance on the fly and don't need to be charged to 100%.

The only thing is does do, charging to 100% after discharge to a low SOC is effectively re-calibrate the BMS to give you a more accurate estimate of total capacity. So it can seem like you've got back more energy (or the battery memory effect).
I was thinking of the Leaf when I wrote my question, like so much of what people believe to be gospel truth today re BEV battery management, it seems to stem from that particular vehicle.
 
Yes, but it will NOT do it while charging to lower percentages than the (virtual) 100%.
Yes, you said, but it’s actually less than 100%, so regardless of what the manual says the BMS is balancing at less than maximum charge, which is all I said.

It’s common for a modern BMS to be capable of balancing cells at less than an actual 100%, the ID.3 manual makes no mention of it, just to charge to only 80% unless you need the extra range.

I also believe you're overly optimistic about the top buffer. It's a generally accepted fact that the e-Niro has a gross capacity of 67 kWh. So 100% SoC will be closer to 97% than 90%. Good thing is though that the NCM622 chemistry has a better resistance to high SoC than NCM811.
We’re talking about the EV6, I don’t own one but the info posted seems to suggest the maths is right.
 
At less than 99% all voltages are more or less the same across cells, so balancing is only effectively possible at 98-100% .
Not that would make any dent to the life of the battery if one cell is at 45% and the other at 46%
Whether you ‘balance’ cells at 4.1v or 3.8v, doesn’t really matter, and my point was that BMSs have moved on in the last decade and they certainly can balance at different voltages.

Personally, I just think this is a subject that far too many EV owners worry about, and the way it’s often written about is just another little barrier to adoption for anybody reading about them on here for the first time.
 
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