Lithium primary thermal runaway?

[robert.t]

So, not that long ago something happened that I did not think was possible and I'm looking for more information about what might have occurred.

I had a device (a remote control, not a flashlight) into which I placed one Energizer Lithium AA battery. As I was using it a couple of days later, it stopped responding so I removed the battery to check it and noticed it was quite warm. I assumed that it had for some reason, been draining more power than normal. I put the battery to one side and grabbed the nearest replacement to hand, which happened to be an Eneloop. I then picked up the Energizer with the intention of checking the voltage and it had got a lot hotter since being removed from the device.

At this point I'm getting a bit concerned, so I double check on here what to do in the case of lithium ion thermal runaway, in the absence of a sand bucket, since I don't have one. On finding out that salt is good for this purpose, I put dumped a load of salt and the battery into an airtight perpsex container and placed that inside a metal pot to contain any fire or explosion. By this time, the battery was extremely hot, but no signs of puffing up or venting like you might expect from lithium ion.

I check on it 24 hours later and find that the battery has cooled down and that the voltage is reading as 1.0V. I don't know if it vented anything nasty, but the airtight container remained intact. I'm not sure, but I'm assuming that most of the drop from ~1.8V to 1.0V was due to it heating itself up - presumably an internal short of some kind.

Has anyone come across this before with lithium primaries? Or is there a potential explanation relating to the chemistry? I had been operating on the assumption that lithium primaries are extremely safe. I've read quite a bit about the conditions that cause thermal runaway in lithium ion cells, but can't find any references to primaries. I am curious if "it gets very hot" is the most serious mode of failure or if it could have gone a lot worse, especially if it had gone into runaway while I wasn't around.

I am also reconsidering the fact that I don't yet own a fire bucket.

 

[troutpool]

I have not heard of this sort of event in an AA lithium battery. There are plenty of stories, though, of serious problems with a mismatched pair of CR123 cells in flashlights. I hope others will offer an explanation for what occurred with your single AA. I'd like to know more too.

 

[Trout River]

I never had a problem with primaries of any kind venting or exploding. ( I have with li-ions, serious issues once. ) I've mix matched primaries for 22 years. My old Surefire M6, when it was king 20 years ago, did actually trip the protection circuit on the SF123A cells though a few times.
Effectively shutting off the light immediately. This only happened on fresh matched cells ironically.

 

[PhotonWrangler]

I had a new Energizer lithium 9V primary battery in it's original skin-pack card package that I tossed into a bag and forgot about. Over time the battery dislodged from it's package and the contacts wound up getting shorted by a screwdriver or some other metal object in the bag. The battery ran itself almost completely down to zero volts. The only reason I discovered it was because I goto a sudden whiff of that fruity-metallic lithium smell when I opened the bag. I dug out the battery and it seemed physically intact - no swelling, blown-out spots or other physical signs of distress.

I no longer store lithium batteries in that bag BTW.

 

[aznsx]

So, not that long ago something happened that I did not think was possible and I'm looking for more information about what might have occurred.

I had a device (a remote control, not a flashlight) into which I placed one Energizer Lithium AA battery. As I was using it a couple of days later, it stopped responding so I removed the battery to check it and noticed it was quite warm. I assumed that it had for some reason, been draining more power than normal. I put the battery to one side and grabbed the nearest replacement to hand, which happened to be an Eneloop. I then picked up the Energizer with the intention of checking the voltage and it had got a lot hotter since being removed from the device.

At this point I'm getting a bit concerned, so I double check on here what to do in the case of lithium ion thermal runaway, in the absence of a sand bucket, since I don't have one. On finding out that salt is good for this purpose, I put dumped a load of salt and the battery into an airtight perpsex container and placed that inside a metal pot to contain any fire or explosion. By this time, the battery was extremely hot, but no signs of puffing up or venting like you might expect from lithium ion.

I check on it 24 hours later and find that the battery has cooled down and that the voltage is reading as 1.0V. I don't know if it vented anything nasty, but the airtight container remained intact. I'm not sure, but I'm assuming that most of the drop from ~1.8V to 1.0V was due to it heating itself up - presumably an internal short of some kind.

Has anyone come across this before with lithium primaries? Or is there a potential explanation relating to the chemistry? I had been operating on the assumption that lithium primaries are extremely safe. I've read quite a bit about the conditions that cause thermal runaway in lithium ion cells, but can't find any references to primaries. I am curious if "it gets very hot" is the most serious mode of failure or if it could have gone a lot worse, especially if it had gone into runaway while I wasn't around.

I am also reconsidering the fact that I don't yet own a fire bucket.

I hate to be yet another person who says 'I've never heard of such', which advances things little for you, but...

I'm VERY interested in any info which may come to light regarding your experience - particularly since it does seem quite unusual. Such unusual / 'edge' cases are in fact the most concerning to me, because none of us expect or anticipate them.

Hopefully someone here with actual cell / battery expertise can speak to this. Although an electronics pro, I have virtually NO such expertise myself, but there are others here who would seem to have some knowledge in that area, and perhaps they can help enlighten us. I'd like to think that perhaps the manufacturer would want to 'post mortem' the cell, but I realize that's (sadly) most unlikely. It's certainly a 'man bites dog' story though

Can I speculate? Sure, I have to do it constantly in my work. How about this:

A 'freak', internal short-circuit condition caused either by physical abuse or an internal manufacturing defect. Unfortunately that won't make me sleep any better though, so hopefully someone around here can beat that wild guess!

Edit: I'm HOPING that maybe some internal protection mechanism ["PTC"?] (in the cell) prevented that from becoming worse than it was. That would make me feel a little better.

I'm also assuming that the Eneloop you replaced it with has not shown signs of heating.

 

[aznsx]

...I then picked up the Energizer with the intention of checking the voltage and it had got a lot hotter since being removed from the device.

After looking at the L91 application guide, and while re-reading your post, I noted this statement - which might suggest that the condition was in fact an 'internal' fault (not a fault condition with the remote), and that furthermore, the "PTC" overtemp device did in fact likely come into play and limit the thermal rise that occurred while the cell was in the remote. If an internal short did cause the overheating, and the PTC did come into play and limit current flow while in the device, it would be reasonable that once the cell was outside the device and in ambient conditions, the PTC may have normalized / 'reset', which then allowed excessive current flow to resume, and that being outside the device this may have allowed the cell to get even hotter, which you then noticed when you went back to check on it. That would all fit together logically.

 

[raggie33]

this is why i always wear sneakers

 

[robert.t]

I'm also assuming that the Eneloop you replaced it with has not shown signs of heating.

Correct. No signs that the remote itself caused a short or anything like that.

I agree with your follow-up that this was most likely an internal fault in the cell. I can say that it wasn't abused in any way. Taken straight from a fresh pack and only a single cell device, so couldn't have mismatched cells even if I tried. The only way it could have taken any sort of abuse is a physical hammering in shipping, but there wasn't anything visibly wrong with it, nor any damage to the packaging, so seems unlikely.

Googling "L91 application guide" was interesting. I found this one:

Energizer Lithium Iron Disulfide (Li/FeS2) Battery Application Manual | Manualzz

This manual provides general characteristics and guidelines for Energizer L91 (AA) and L92 (AAA) Lithium Iron Disulfide batteries, including their advantages, discharge characteristics, safety features, and transportation regulations.

manualzz.com

The fact that it has the PTC thermistor and a pressure release valve indicates that there would be some risk of explosion were those absent. Also interestingly, primaries have been explicitly banned from cargo shipments on passenger aircraft. There was no mention of why that is the case, but it's clear that primaries are called out explicitly, and even have their own label, quite separately from lithium ion.

I haven't read it yet, but there's also a much longer version of that manual, though it's also a lot older so it doesn't have the new shipping guidance:

https://ia801701.us.archive.org/23/items/Electricity-prep/Batteries/Lithium/Energizer_Lithium_Application_Manual_L91_2001.pdf

I might try reading through that one properly tomorrow.

 

[aznsx]

Correct. No signs that the remote itself caused a short or anything like that.

I agree with your follow-up that this was most likely an internal fault in the cell. I can say that it wasn't abused in any way. Taken straight from a fresh pack and only a single cell device, so couldn't have mismatched cells even if I tried. The only way it could have taken any sort of abuse is a physical hammering in shipping, but there wasn't anything visibly wrong with it, nor any damage to the packaging, so seems unlikely.

Googling "L91 application guide" was interesting. I found this one:

Energizer Lithium Iron Disulfide (Li/FeS2) Battery Application Manual | Manualzz

This manual provides general characteristics and guidelines for Energizer L91 (AA) and L92 (AAA) Lithium Iron Disulfide batteries, including their advantages, discharge characteristics, safety features, and transportation regulations.

manualzz.com

The fact that it has the PTC thermistor and a pressure release valve indicates that there would be some risk of explosion were those absent. Also interestingly, primaries have been explicitly banned from cargo shipments on passenger aircraft. There was no mention of why that is the case, but it's clear that primaries are called out explicitly, and even have their own label, quite separately from lithium ion.

I haven't read it yet, but there's also a much longer version of that manual, though it's also a lot older so it doesn't have the new shipping guidance:

https://ia801701.us.archive.org/23/items/Electricity-prep/Batteries/Lithium/Energizer_Lithium_Application_Manual_L91_2001.pdf

I might try reading through that one properly tomorrow.

I in fact do 'sleep better', because now I know that if some internal failure occurs, due to any root cause including mfg. defects, (which will always be a possibility), the 'system worked' as designed. It 'failed safe', which is more than be said of a lot of things!

BTW, since I 'referenced' something, I probably should have included a link just to be civilized.

I went to my 'bookmark' for the factory 'Datasheet', which is here:

https://data.energizer.com/pdfs/l91.pdf

Then, hit the link in the specs for 'more details', which links to the app manual here:

https://data.energizer.com/pdfs/lithiuml91l92_appman.pdf

The latter is fairly comprehensive, and being on the mfgr. site, should be 'current'.

Cheers