I said check the data sheet. What does the p42a sheet say?
It gives a chemistry:
https://www.molicel.com/wp-content/uploads/00058ar-Molicel-SDS-Y2020.pdf
It could be compared to Samsungâs cell chemistry:
Now that I know some ion cells CAN be discharged down to even as low as 1v and the manufacturer even says theyâre good, makes me think those people telling me Iâm a danger for JUST ASKINGâŚand repeatedly insulting me⌠speaks for itself. Good thing I did question answers and didnât just assume
Oooooor, testing was done on one cell, and one chemistry, for one application. And now that you know that the manufacturer has established a test to verify this you can then test various different manufacturers and chemistries to see if they will have the same results.
Or you can look long and hard to find the one confirmation in a sea of conflicting data and just play to your preconceptions. This seems like it was the plan all along though - you want data and proof? Take those low cells from the salvage and a few good ones and start cycling them. Take some to 1v every time, some to 2.5. Log everything and report back
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50s spec sheet says do not exceed the discharge limits or it will lose performance characteristics but then 3 pages later it looks like a quote from the chart you showed: over 1v it can be changed at a very low rate but can be changed. This doesnât mean to me that all cells can be blanketed by this but it does seem to indicate that the Samsung cells can be charged as long as the dont go below 1v.
Panasonic and Sanyo say similar related to recharging over-discharged cells.
Itâs not one cell, or brand, or chemistry, or application. In fact it seems maybe even all ion cells that have been over discharged, possibly all the way down to 1v, can be recharged again. This is according to the manufacturers.
There are a number of issues with what youâre saying.
Youâre currently using cell datasheets as some kind of âAh ha!â to counter the feedback from people in this discussion who have what is most likely, much more experience, expertise, and nuanced understanding of the topic. These include people who havenât insulted you, and have explained in great detail the answers to the questions that could be gleamed from what youâve been writing.
As a result of that, youâre very much misinterpreting what the numbers on datasheets mean.
To start, those datasheets arenât written for you. Theyâre written for engineers to use as design guidance for devices with integrated battery packs, around which BMS systems are designed and also integrated. Those engineers span from electrical engineers, mechanical engineers, and integrations engineers who look at a system/product from different angles, and then coordinate their understandings to arrive at a final system.
This is also how BMS IC chips are treated. Those chips have their own spec sheets, with voltage cutoffs, temp ranges, etc. And they also have reference schematics that show examples of how to implement the chip into a circuit. What they DO NOT show, is the ancillary circuits needed to properly power the IC, protect it from the battery circuits itself, or tailor specific functions of the end device alongside what the IC is designed to do. This encompasses the assembly of the device (since factory or end user assembly has to be accounted for) and failure modes that the IC doesnât accommodate.
Thatâs all to say, that you simply cannot point at a datasheet and go âSEE? I WAS RIGHT!â
When you do that, like you just did, you display ignorance and a lack of understanding of the topic, and so the conclusion that youâve dug, incorrectly, from these sheets, doesnât end up serving you or anyone else. And itâs also wrong.
Youâve ignore other lines in the sheet, like the fact that 2.0v is the BMS shutdown voltage.
That means that in devices using those cells, the BMS doesnât just disallow charging and discharging, it has to completely shut down. Those barriers are separate and distinct from operational cutoffs. Shut down means the end user is completely barred from using the device, period. No charging, no turning it on.
The manufacturer is saying that if the battery hits that point, the device is to be deactivated.
Thereâs also this, as a qualifier of the data in the sheet:
âThis Specification shall not apply to special applications requiring a high degree of quality and reliability where the failure or malfunction of the products may directly jeopardize life or cause threat of personal injury.â
Which makes your statement here:
^This statement, absolutely incorrect.
Look, you can do whatever you want with your own stuff. But this thread is a reference point for other people looking to learn about pack building. So the sweeping incorrect statements youâre making here about cell voltages, are not just wrong, but theyâre irresponsible.
This isnât helpful.
I point colleagues and DIY one wheel builders here for reference, and this whole shit show of a conversation could have absolutely been avoided if people didnât use this thread as griefing/trolling entertainment.
Normally I donât care, but this whole thing is now being dumped on my doorstep and Iâd like to keep referring people to this thread.
Iâm telling you to trust the people who literally work on these things professionally.
So as a professional, it is my professional opinion that youâre looking at this all wrong. And youâre doing so at your own peril.
Backtracking a bit.
There is a right and wrong. Degrees of risk donât exist in a vacuum, and this is a publicly viewable forum that outsiders view for reference and guidance.
And so the angle at which you or anyone comes at a conversation about technics of a volatile and dangerous part of a dangerous hobby, matters. The good or bad faith from which an argument happens, matters. It all matters, and the context in which disagreements happen, also matter.
Personal risk ends where the publicly provided opinions and information begin.
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Iâm so much for this. vesc should definitely be aware and responsive to bms state in all our boards.
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The data sheets say they can still be used if theyâre discharged to 1v. Itâs not complicated and doesnât need an âexpertâ or âengineerâ to figure it out. It is an âahaâ moment where know-it-allâs tell me Iâm not smart enough to understandâŚand they tell me the wrong thing. I donât care how many batteries you sold and how much of an expert u think u or what customers u send here.
This forum is for learning. Anyone saying itâs not appropriate for me to write that u can still use at least some ion cells that hit 1v, because someone might not be familiar enough or theyâre not knowledgeable enough and itâs too dangerous for them to hear⌠whatever.
The thread is a shit show because I was repeatedly insulted and condescend to just for asking a question ⌠then told to just follow along without any evidence given. And then you want to continue with the charade that Iâm not understanding. I understand fine.
itâs a fascinating revelation that manufactures state 1v cells can be still used, but sad because the discovery is an assault to some egos and it canât be further discussed
They donât state that, and if you ask them directly, they will tell you as much.
And you can not care about whatever. You used superglue instead of soldering balance wires. Youâve shown photos of awful work and a pattern of ignoring experts.
I tried to lay it out. Mooch tried.
You refuse to listen, and itâs so unfortunate how ignorant you choose to remain.
I didnât say I send customers here. I send learning builders here to read. And youâre soiling this thread with more of your absolute nonsense.
Shame on you.
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Yes manufacturers state specifically 1v cells can still be used. Read the data sheets. Itâs like a brick wall.
U should add they were glued balance wires on a POTTED, LIFEPO4 battery with 50 Miliamp discharge balancers. Theyâre still working fine. Some of us like to do experimental stuff. Are you claiming that what I did is dangerous?
U send people here to learnâŚbut not about the posssible low voltage threshold of batteries obviously. Fact is u just didnât know the manufacturers state 1v as a possibility
Shame on u.
But thatâs a real question above. U think my glued balance wires are a danger, in ur expert opinion.
I refuse to listen? To what. @Battery_Mooch what are you and he trying to get through to me that Iâm missing? That while the data says 1v is acceptable⌠itâs still not possible to use them? That obviously is a contradiction to what the data sheet is saying.
It says pretty plainly that they will lose some of their performance characteristics when discharging below 2.5v. I donât think that qualifies as good. It also says that the charge current needs to be especially low which most chargers are not going to do automatically. Instead of exploring what this means you just keep slapping the word win on it to do what you want man. Electrical systems are not cut and dry, they are a balance of many many complicated factors.
If it was the intention of the writer of the data sheet to have 1v as the limit wouldnât they have put that somewhere more prominently and explicitly, like on the first page with all the limits? Instead it is edge case limit with qualifiers and everyone with engineering experience says itâs a bad idea.
Go and do something thatâs a bad idea - thatâs totally fine, but donât pretend like itâs a good idea.
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Clearly, I made a mistake. I took @hummieee 's bullshit seriously, and as a result, I wasted my time. As did Mooch and anyone else who mistakenly gave that humanoid the time of day.
Iâm sorry @jack.luis for what I said prior. I was wrong. You had the better idea to just mock this person.
@hummieee I donât know what your actual malfunction is, but your entire post history on this thread is a dumpster of shoddy work, bad ideas, bad faith arguing, and willful ignorance.
I didnât take my own advice, and I regret it. I donât stop on the streets of NYC to talk to people yelling crazy things into the void, and I shouldnât have done that here.
My bad.
@hummieee is the new @tech.shit
So, if youâre still posting here, I wonât be. Enjoy, you win.
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I learned form @Battery_Moochâs answers. I even directed people to them.
I appreciated the perspective in your answers. I appreciated you putting forth opinions reasonably and that you didnât engage in mockery. 
so⌠I also appreciate @hummieeeâs questions for giving me those responses.
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The data sheet says they can still be used if 1v. Itâs a question of safety not if itâs good for the cell. I mean âgoodâ in thst itâs possible. That was the question all along
But @TheBoardGarage tell me what Im missing? How am I misunderstanding. If a data sheet literally states a cell can be down to 1v and recharged⌠what am I missing?
Do u think my glued on balance wires are a danger?
If you donât consider his response mocking⌠I think ur just being nice
And I didnât just bring the questions. I also brought the answers.
Yes⌠yes u can still use a cell that gets to 1v if u believe the manufacturer data sheets.
I did think his initial post was trying to be reasonalbe.
I appreciate that observation as well.
Also this
Felt like this
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@jack.luis @TheBoardGarage do you think the manufacturer states itâs acceptable to recharge a cell that goes to 1v?
Just a yes or no answer please. Letâs see if ur egos can do it.
I have information and examples of practical reasons as to why the data sheet says those things but I cannot disclose those due to an NDA I signed.
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I didnât think u could.