Lithium-ion battery safety 101

The length and width of a protected cell is bigger

Thank you Jack! Post has been updated.

I’d recommend putting citations to sources behind the statements.
These batteries are “evolving” rapidly and the age, and source, for each belief is important to have on record.
I don’t mean you have to be responsible for pointing to the best source — just point to where you found what you felt reliable information, so people can go from there.

Regarding storage of batteries in a car during summer, there is some disagreement as to the actual risk:

I’d suggest rewording the sentence to read:
“If you are going to store your flashlight in your car in the summer, primary batteries are recommended over Lithium-Ion rechargeable batteries.”

And for some reason, the statement, “Protected batteries are safer than unprotected batteries,” irks me. Just a style issue. I would have phrased it, “Protected batteries are generally safer than unprotected batteries.” That’s because there are so many exceptions where unprotected batteries are as safe or safer than protected batteries. For example, PCB’s have been known to fail in multi-cell applications. Or the most simple example of a high quality unprotected cell versus a low quality protected cell. But I’m getting picky. :wink:

All I want to say is: Thanks for putting this thread together! :GRADE:

Edit: Oh wait, as long as we’re allowed to be ‘picky’ here, it should be cell/cells rather than battery/batteries. :wink:

Is it normal for liIon cells to get a bit warm whist charging?
I’ve never felt any of mine go above ambient.

And not to be a knob,but what’s the difference? That’s one thing I’ve never seen explained.

Battery vs Cell I beat David to the punch :wink:

Cheers, makes sense now.

Thanks! beautiful thread!

Great info, looks pretty complete and easy to read.

One thing that you may want to expound upon is;

“Don’t over charge your batteries.
Max voltage should be 4.2V”

Maybe explain that most chargers have a tolerance of 1%, so for instance 4.22 volts is not a problem.
Hate to see new members obsess over .02-.04 volts.
Also all voltages should be measured after a short “rest period” and not instantly after coming off charger.

This also does not cover LifePo 3.2 volt or 4.3, 4.35 batteries, but that is another show as they say

Thanks for putting this list together Mr. Scott
Later,
Keith

Hank,

Thanks for the comment. References are good. Unfortunately I’ve been copy-and-pasting things into a word file as I came across them and haven’t been saving the references. I will attempt to find as many citations as I can.

Done and done. Thank you! Picky is fine.

> copy-and-pasting thing into a word file

If you still have the original text you copied and pasted, just paste a chunk of it back into a Google search as a quoted string; likely it’ll take you right to where it first appeared.

If not, at least, going forward, it’s easy to capture the source URL as well as the words you want, which will help as this evolved.

This should absolutely be a sticky.

What is “short” with respect to “a short rest period”? As a newbie that is one of my first thoughts.

I thought I’d read that tolerances were +/- 0.05v for chargers. Of course I can’t find the citation right now. >:-/

A few minutes should be fine for accurate voltage measuring. Wait until the cells cool down to use them in their respective device.

You’re right. I was thinking Short being 5 minutes. Sorry I did not include an actual time frame.
1% tolerance in this case would be .042 volts so yes near .05 volts would be a reasonable variance.

Members should also realize that the health and even size of a cell can also effect voltage termination values.
My experience has shown that many times a smaller cell such as a 16340 may end charging at 4.17- 4.18 where as a normal 18650 on the same charger would come off at 4.20-4.22.
So if the user only were to try the 16340 cell they may think there is something wrong with the charger when this is not the case.
As in many things in life you are looking for a suitable safe range and not an absolute value on each and every cell.

I agree with your recommendation that the user chose a good name brand charger and not just an unmarked charger.
Thanks

MR. SCOTT, WELL DONE!!!

Well done, I am in awe that you took the time to do this, and I think that it has the potential to save an unknown number of li-ion battery users a whole deal of time/grief/injury.

I have some thoughts. What I am going to say comes from having worked with many people who are new to the field I work in and trying to be more effectively informative without wasting time or coming across as condescending.

1. Delete the first two paragraphs. You do not need to excuse yourself for trying to save people bodily injury. Acutely, the first paragraph could be a few pictures of people that have suffered such injuries due to the improper care of li-ion cells, although that may come across as offensive or heavy-handed to many. I think a quick explanation of the dangers of li-ion cells followed by a brief explanation of what is contained in the guide would suffice as a more pleasant alternative to that, but getting to the point quickly and concisely, especially in a thread designed on promoting safety, is important.

2. The section on a lithium battery fire is not substantially alarming. It needs to be much more of a noticeable bullet point. I’ve seen several “venting with flame” claims by manufacturers that seem to have the intention of assuring the customer that no real danger is present. The chemicals released during a li-ion fire are bad enough that medical attention is necessary immediately instead of the next day to prevent chronic problems.

I think you did a bang up job on this and I appreciate how much work it is to put something like this together, and I thank you for doing it. Kudos to you Mr. Scott.

Couple of concerns.

This thread is posted in the “Rechargeable Batteries” category not the “Rechargeable Cells” Category.
HKJ only seems to review batteries, not cells.
That is a lot of editing for this post.

:slight_smile:

Picky, picky, picky. “Cells” and “batteries” are generally understood to be the same thing by the average person, though when being picky there is a difference. In this context I’d say the terms are understandable and interchangeable- remember the audience and address them as they will best understand. When addressing noobs I usually put something like this: batteries (cells).

On the preambles, yes do shorten them. Simply say the guide is aimed toward the novice users and is not meant to cover every aspect of LiIon rechargeables but only to provide a general guide which will allow their safe use.

On chargers add more emphasis to the absolute need for known safe chargers. An under-performing cell can be safe in a good charger but no cell is safe in a poor charger.

On the dangers of cheap cells, add or link to venting with flame vids and pics; be graphic about how serious these dangers can be. Also add something more on not breathing the fumes at all as this is probably the most potentially harmful aspect of most venting episodes.

And I’m looking forward to seeing this get “stickied” and referred to regularly- it deserves no less!

Phil