How Do Most Lithium Ion Batteries Behave When They Are Approaching End Of Life?

[Kurt_Woloch]

I can't find any articles stating worn or aging cells are more dangerous.
I would be interested in some form of study or proof of this.

I have no study nor proof, but some solid theories how worn or aging cells might be more dangerous...
1. The rising IR causes the cell to heat up more and more under the same load. If it gets too hot, it might go into thermal runaway, which a new cell would not do under the same load.
2. If used together with other cells, at least badly done battery packs might slowly fall out of balance, which might cause some cells to get too high or low in charge, which is dangerous as well.

 

[RetroTechie]

The rising IR causes the cell to heat up more and more under the same load. If it gets too hot, it might go into thermal runaway, which a new cell would not do under the same load.

The chance of thermal runaway, and the amount of damage that would do, is directly proportional to the energy contents of a cell. Old / worn Li-ion cells have lowered capacity, can't deliver high currents anymore, and for those reasons alone they're less dangerous. Just go watch some YouTube videos of Li-ion cells blowing up: almost without exception, you'll see energy being fed into the cell as it happens (12V car battery wired to 3.7V Li-ion cell etc). Fully charged cell on its own (perhaps overcharged) - hmm not so much. Maybe if short-circuited or punctured with a nail. Perhaps if you take enough high-capacity cells & wire them the wrong way. Worn out / old cell: not happening, energy contents does not suffice to provide fireworks that are worth the effort.

If you think otherwise then please provide some pointers otherwise stop scaring people with a non-issue.

Of course the higher IR of old Li-ion will limit its usefulness. There is nothing 'tricky' about that: apply intended load. Fresh cell will have no problem. Old cell with good remaining capacity but increased IR won't be able to handle it. Old cell with decent IR but lower capacity won't handle it either. End result is the same: cell unfit for purpose. And it doesn't matter much whether it's due to capacity loss, higher IR, or some combination thereof.

Likewise when selecting cells I don't care what % remaining capacity is of rated capacity for a new cell of that type. I just apply a load that reflects common usage for me, and performance (capacity) at that load is what counts. Can't handle that load? Out! To little capacity @ that load? Out! The rest can stay. Specifications or brand are interesting, but don't decide whether a cell is kept or not.

 

[Got Lumens?]

I am unaware of any public studies as well. There would be a need to separate and compare the differences of the many different chemistries available.
There have been posts/articles over the years of damaged cells causing troubles, especially in multi cell configurations.
Posts on accidentally mixing in a discharged cell in a multi cell light has led to incidents.
Many Manufacturers that sell these cells limit their warranty period to 12 months or less.
IMO, the quality of the cell along with the care, usage, and the type of charging will influence it's useful life span.
I have cells that are 5 years old that work fine, and I've retired cells with ~20 cycles on them.

I dissected a Makita 18V power pack that the charger would not charge. One of the cells only had 1.3V the rest were above 3.7.
I found the same thing on an old laptop battery pack. I still have a few laptop cells that work fine. Unbalanced multi battery configurations
can cause an un-safe condition. This is why they won't charge, the difference between cells is too great and the charger shuts the pack down.

 

[archimedes]

My (not an expert) understanding is that many of these chemistries are affected by dendrites.

These tend to form especially under conditions of low SoC. Once formed, they tend to grow over time.

The highest capacity (when new) cells, meaning the more and/or thinner layers in the cell, tend to be at the highest risk of damage from dendritic growth.

 

[cy]

most of the cells that I EDC .. currently li14430 or CR2 size, all 10+ years old
what I've noticed is .. as cells age charger when set to 1C tend to draw way more than 1C amount of amps and/or milliamps.

for instance .. charger set to 1C results in cell being charged hard enough to heat up cell or not good. so instead of charging at 1C .. I'll set charge rate to 600 milliamps or what ever.

this is assuming one has a charger with settings. not everyone has a state of the art charger. years back I realized the greatest danger from using li-ion cells occurs during charging. hence justification to spend extra $$$ for extra safety factor.

just so happens that accurately charging lithium cobalt cells appears to extend life as well.

 

[WalkIntoTheLight]

most of the cells that I EDC .. currently li14430 or CR2 size, all 10+ years old
what I've noticed is .. as cells age charger when set to 1C tend to draw way more than 1C amount of amps and/or milliamps.

for instance .. charger set to 1C results in cell being charged hard enough to heat up cell or not good. so instead of charging at 1C .. I'll set charge rate to 600 milliamps or what ever.

I generally charge all my 18650's at 1 amp. It's a good compromise rate; doesn't take forever, nor does it stress the cells.

I notice that on some very old laptop cells, which are rated for only 1.1 amp charging (when they were new), they don't overheat with 1 amp. However, the charger very quickly will go from the CC phase, into the CV phase. This decreases the charging current by design, and a good chunk of the charge will happen in that CV phase. That's because the high internal resistance requires more voltage to charge.

On a high-drain new cell, almost all the charge comes from the CC phase, because the low internal resistance doesn't require much voltage differential to charge it.

Anyway, my point is that if you charge at a reasonable rate, I wouldn't worry too much about whether the cell is old or new. A good charger will adjust. Of course, always feel the cell occasionally to make sure it's not hot. If it is, something might be wrong and presenting a safety issue.

Oh, and there's plenty of dangerous cheap chargers on the market. So, make sure you buy a known brand that makes good chargers.

 

[MarioJP]

Hey guys,

I have to give thanks for this thread that made me realize that when it is time to replace the cells lol. I have one particular cell that starts to heat up even at 500mA charge rate.

This cell has reached 45c temp and luckily the charger safety features kicked in as it was flashing red. This cell was quite hot.

Any idea why this cell heats up like that? I noticed the heating up starts when the cell hits around 4 volts, not even close to hitting 4.1 yet.

I finally ordered replacement cells which are 18650GA an upgrade from NCRB's i suppose. Not liking how this cell heats up and it is making me nervous lol.

Any idea what's going on internally with this cell?

Thanks.

 

[john61ct]

growth of dendrites causing internal shorting

 

[Got Lumens?]

Any cell that heats up to the point You can't touch it >125° is bad.​

There also could be subsiquent damage to the cells insulating layers from the excess heat further accelerating the decay.
Do this Take the Voltage of that cell. You said You charged it previous to ~3.9-4.0V?. Let the cell sit for a week and test the voltage again. I wouldn't be surprised if it were close to or below 3.5V. This test verifies that the cell does need to be retired.

 

[MarioJP]

One week later, this cell in question remains at 4.12v (end charge termination was a bit high when cell was charged) But one thing is clear, when together with the other cells.

This is the only cell out of the 3 that has far less capacity and voltage jumps higher when charging and drops futher down when discharging than the rest of the cell group.

At first, i thought this cell had more charge than the rest, so what i did is discharged them all down to 3.00v equally. Did a slow charge and fair enough, the voltage in this particular cell kind of jump a bit higher than the rest after 5 min or so.

Sometimes it can be off by .10v from the other 3. So yes, one week later, cell remains at 4.12v while the other 3 remained at 4.15v

So does not look like it is a short, but i think this cell is nearing end of service much sooner than the other 3 due to abnormally heating up during charging even at low currents.


Just out of curiosity out of this thread, anymore ideas as to why this cell is giving out sooner than the rest? They were all used equally in a power bank.

Luckily the cells are in parallel configuration, so that's good at least.

Strange behaviour from li-ions lol.

 

[Got Lumens?]

One week later, this cell in question remains at 4.12v (end charge termination was a bit high when cell was charged) But one thing is clear, when together with the other cells.

This is the only cell out of the 3 that has far less capacity and voltage jumps higher when charging and drops futher down when discharging than the rest of the cell group.

At first, i thought this cell had more charge than the rest, so what i did is discharged them all down to 3.00v equally. Did a slow charge and fair enough, the voltage in this particular cell kind of jump a bit higher than the rest after 5 min or so.

Sometimes it can be off by .10v from the other 3. So yes, one week later, cell remains at 4.12v while the other 3 remained at 4.15v

So does not look like it is a short, but i think this cell is nearing end of service much sooner than the other 3 due to abnormally heating up during charging even at low currents.


Just out of curiosity out of this thread, anymore ideas as to why this cell is giving out sooner than the rest? They were all used equally in a power bank.

Luckily the cells are in parallel configuration, so that's good at least.

Strange behaviour from li-ions lol.

I upgraded to an Xtar VC4S charger.
It can test and rate a cell. It can answer questions like capacity or ability to deliver current.
It's best to have as near matching cells as possible in a multi-cell applications.
If the cells were matching when You placed them all into service, most replacements won't match the (good)cells that are still in your multi-cell configuration.
I would retire the other working cells to single cell applications and upgrade the multi-cell application(s) with new matching cells as needed.
I can say Your attentiveness with the use of Li-lion cells is a good safety practice.

 

[WalkIntoTheLight]

Just out of curiosity out of this thread, anymore ideas as to why this cell is giving out sooner than the rest? They were all used equally in a power bank.

Sometimes, it's just bad luck. We don't really know the quality of the cells we buy. Most grade A cells probably go to the major manufacturers of battery packs for tools, laptops, vacuums, etc. They're likely the most consistent quality.

It's just a guess, but the cells that resellers get may be rated lower, and are less consistent in quality. That doesn't mean they're bad, but it's more likely you could get one that's a little weak.

Remember, we're not supposed to use lithium-ion cells at all. None of the major manufacturers want resellers to sell them to the public.

 

[MarioJP]

I upgraded to an Xtar VC4S charger.
It can test and rate a cell. It can answer questions like capacity or ability to deliver current.
It's best to have as near matching cells as possible in a multi-cell applications.
If the cells were matching when You placed them all into service, most replacements won't match the (good)cells that are still in your multi-cell configuration.
I would retire the other working cells to single cell applications and upgrade the multi-cell application(s) with new matching cells as needed.
I can say Your attentiveness with the use of Li-lion cells is a good safety practice.

I was going to get the Xtar Dragon, but the SkyRC MC3000 changed my my mind. The ability to update it's firmware is what convinced me.


And yup, i am now using brand new cells plus i upgraded my power bank that now supports QC charging and uses 6 instead of 4 cells.

I like the fact that this new power bank has a locking mechanism to keep the cover from sliding open and how the metal contacts are tucked away from being exposed unlike the old one.

These are the brand new 18650GA, and the seller was liionwholesale. They threw in 3 battery cases plus a 18650 XML-T6 flashlight for free.

I do notice a "B" marking on all 6 cells. So i am guessing it's an internal grouping letter?

As for the old cells. They will be used for light duties such as now my single cell flashlight, and bluetooth radio.

This will be my 2nd set of cells since introduction to cylindrical li-ion world. Before that, it was just eneloops, sure they were safe, but they just don't cut it these days anymore at least for what i use them for. AA power banks are a joke lol.

And I hate devices with sealed-in batteries from x brand company as you are at their mercy should something goes wrong with that device lol.



And lastly, Awesome seller if looking to buy new cells.

 

[john61ct]

Even perfectly identical cells will wear unevenly over time depending on the wiring layout and their position in the pack.

 

[Got Lumens?]

I do notice a "B" marking on all 6 cells. So i am guessing it's an internal grouping letter?

As for the old cells. They will be used for light duties such as now my single cell flashlight, and bluetooth radio.

I am guessing the "B" indicates the tier of acceptance. Where as most all "A" cells are marketed to pack builders.
There is one question You can ask of the vendor, Are those cells 2 or 4 terminal cells? 4 terminal cells provide more consistent
High Discharge voltage compatibilities.

 

[MarioJP]

I am guessing the "B" indicates the tier of acceptance. Where as most all "A" cells are marketed to pack builders.
There is one question You can ask of the vendor, Are those cells 2 or 4 terminal cells? 4 terminal cells provide more consistent
High Discharge voltage compatibilities.

Good to know. I'll def look into it. When they did arrived, they were almost empty around 3.5v right out of the package. The invoice does states that due to shipping regulations, the cells were shipped almost empty and to charge before first use.

So the cells were discharged before it was shipped.

So far they seem consistent during charging. Definitely at it's rated capacity (3000mAh+)





Now as for the old green cells, they still hold quite of charge even after 4 years of use and they really last using them for my bluetooth speaker. Just dang.

Although i may just recycle the abnormal cell and just be 3 instead of 4 cells in this group.


Update: Decided to just recycle this cell that heats up abnormally. So this is how Li-ions behaves as they degrade and finally, EoL.


But first: discharging the cell to what i like to call, recycle mode lol.

 

[snakebite]

was the heater a red sanyo?
https://secondlifestorage.com/showthread.php?tid=303&highlight=sanyo+heaters

Hey guys,

I have to give thanks for this thread that made me realize that when it is time to replace the cells lol. I have one particular cell that starts to heat up even at 500mA charge rate.

This cell has reached 45c temp and luckily the charger safety features kicked in as it was flashing red. This cell was quite hot.

Any idea why this cell heats up like that? I noticed the heating up starts when the cell hits around 4 volts, not even close to hitting 4.1 yet.

I finally ordered replacement cells which are 18650GA an upgrade from NCRB's i suppose. Not liking how this cell heats up and it is making me nervous lol.

Any idea what's going on internally with this cell?

Thanks.

 

[MarioJP]

was the heater a red sanyo?
https://secondlifestorage.com/showthread.php?tid=303&highlight=sanyo+heaters

Wow that thread pin pointed the exact issue i was having. Was because it was the green Panasonic cell or ncr18650B which is the above cell in the pic.

As far as the GA or red one goes. No problems at all as they are still new. Not even on the tenth cycle yet.

It was the B's that were having heating up issues. At that time, that cell starts heating up around 3.9v and voltage just doesn't climb anymore.

Another pinpoint from that thread is i did exactly that. Let that cell rest for a few hours and then slow charge, and that's when the voltage climbed to 4.2v without generating much heat.

And yes, like what that thread says, it is only hiding a future problem and would have to repeat this every time. Not worth the effort and better off recycling it in the end.

But good to know that i am not the only one. Pinpoint accuracy wow.