I have heard that too. But is it always true? I assume there are two ways the cell can go to 0v. Number 1 being that it is self-discharging due to health issues. But number 2 would be an external influence ran it down to 0v. For the second case I imagine it could be just fine if it was a quality cell to start with. Anyone agree or disagree?
Yes I don’t think they are protected.
Sorry I meant to say they accepted 2300mah on average. They are 2ah Sanyo batteries.
I don’t intend to use them. It’s just an experiment. I will check the voltage drop from month to month
I just prefer to be safe- please read up on the dangers of li ion cells as they can explode if miss used, charged or over discharged.
I see by your name you like mx bikes - i had a go on a honda CR 500 once- now thats a mans bike, my arms were longer after that.
overdischarging then charging can cause internal shorts that may not show up right away, they can catch on fire just sitting there or under use later, i would keep them outside!
wle
those are a somewhat safer chemistry(not li co)
but it is still not good to do!
i have seen datasheets that stated that <1v is a do not charge even with newer safer chemistries.
and the fact that something bad happened to damage some cells means recycle it now.
This.
I think that is what happened in the instance below:
Charging current only at .05amps is maybe why they have survived thus far.
Throughout charging I felt the temperature of the batteries and estimate none got hotter than 30*C.
Just beware. If an internal short should develop at some point during charging it might give you no warning.
best way to have a lithium cell soon on fire, getting you thousands of $ hospital bill plus health damage
throw em away, buy new quality cells for 5$ each
This is really irrelevant.
The fact is that when li ion cells are overdischarged the copper anode dissolves into the electrolyte, then when brought back above 2 volts the copper ions precipitate where they are, not on the foil where the copper belongs. This leads to internal short. Thermal runaway can happen during charging or thereafter with increasing risk if the cell continues to be cycled and used.
Irreversible physical changes have taken place in the cell.
An overdischarged cell is an electrically abused cell.
These damaged cells may continue to function, but with increased risk of failure (including rapid dissassembly).
“Fire Protection Research Foundation ”Lithium-Ion Batteries Hazzard and Use Assesment”:http://www.prba.org/wp-content/uploads/Exponent_Report_for_NFPA\_-\_20111.pdf
You should stop playing with those batteries and recycle them.
It is for your safety.
Anything below 2V should be recycled.
Better safe than sorry.
Test engineer for brushless garden equipment should know that.
Don’t even think about it, get rid of them ASAP. Your life and home isn’t worth the risk
Don’t Really see the harm,he’s a test engineer so likely well aware of what he’s experimenting and any associated danger.
The op has already stated his intention is to use them “I don’t intend to use them.
It’s just an experiment. I will check the voltage drop from month to month”
As long as he’s taking precautions in case something should happen to them and stores them ideally outside away from the house then I don’t see the problem.
The world and this forum would be a much poorer place if people weren’t curious and didn’t experiment.
People do far far worst and often totally pointless things to these cells, he just wants to see how they hold a charge over a few months for his own curiosity, can’t see any harm in that, personally I’d be interested to see how they hold up.
Whilst it’s a very good idea to warn people of the dangers, - especially inexperienced people -
Of these cells, if people relentlessly hammer the point ever time someone mentions li ion cell, it rather losses it effectiveness especially to the very people who relay do need educating on the dangers of these cells.
Just my opinion of course 
This is not the cause of the risk, the danger is that below 2.5V chemical changes happen that can lead to crystal growth over months or years of normal functioning then suddenly the cell explodes with no warning. There is no known way to measure this without taking the battery apart months or years later by someone with the equipment to examine it microscopically
The first indication that your brother isn’t sufficiently well informed is that he gave you a dead lithium battery pack. Or, maybe he didn’t know it was flat and assumed you would know to recycle any zero volt cells rather than charge them. In any case I would not assume someone else’s knowledge base when it comes to my own responsibility. The warnings are there because of real risk. You can’t see inside a cell or test it to know whether or not it’s about to fail, all you can do is follow the guidelines regarding treatment of abused cells and whatever the cause, zero volts constitutes abuse.
Thank you for the explanation, it makes all the difference. Simply labeling something as dangerous has lost it’s potency these days.
+1
Exactly.
I am using threshold of 2V and below because some cells will go down to 2V no problem.
The point is - do not make experiments with li-ion cells unless you have ready and operable >> Foam extinguisher, CO2, ABC dry chemical, powdered graphite, copper powder or soda (sodium carbonate).
Take a look at new LG 18650 batteries and warning printed on them (NO more bare li-ion batteries for us).
Sony the same story
Samsung will follow
Actually its worse, don’t do this unless you have a fireproof automated system that monitors your batteries 24/7 and can automatically extinguish flames with lithium fire fighting powders (water is ineffective on lithium fires i believe).
Also you need to prevent explosions from reaching a human if it explodes while in use (build flashlights from 3 inch thick aluminum with pressure vents that filter hazardous fumes, not likely.
Before I decked it out with an automated fireproofing system, I would put them in the garage with a bag of play sand above them. If a fire starts, the heat or flames burst the plastic and bury the cells in play sand.
Seems like a lot of work for cells that are obviously bad. Throw them out and be done with it.