I have been getting a lot of used battery packs from different devices and salvaging the LiOn cells when possible. In addition to the normal things to look for to sort out the bad cells from used packs, I have found something I have never heard anyone mention before. The smell of a LiOn.
I found out about this by opening up a cell phone battery to see what was inside. It was one of the flat square type so was of no use to me in lights. Inside was layers of a foil like material surrounded by a gray powder (Lithium I presume). The notable thing was the intense and unique smell. Nothing else I have ever smelled smells like it so it is very distinct and easy to recognize.
While sorting some old 18650 laptop pulls, I caught a whiff of that lithium smell and started looking for the culprit. The cell I found had a light to medium lithium smell coming from the positive contact. I assume it vented at some point and was bad. I checked it with a meter and sure enough, it was low voltage. I put it in my I4 and it refused to charge it.
So, it sounds weird and you will have to familiarize yourself with what Lithium smells like first but it is a useful tool in sorting the bad LiOn cells or recognizing when one of your cells has vented and needs to be pitched.
Ok I’m worried now… Last week I noticed one of my Panasonic 3400’s smelt rather nice. . I have two in rotation for my edc, which I’ve dropped 10+ times onto concrete, they behave normally, charge cool etc but I wonder now if the top of the cell has been fractured although no leakage is visible. What should I do? It’s like a sweet chemical smell, a bit like Cellulose paint if you’ve ever used that, I’m gonna have to flick a lid off a tin and stick my nose in I love the smell of that stuff ha
If it’s a metallic sort of smell with a burning effect on your nose and throat - lose the cell in a hurry.
If it is leaking HF you really, really don’t want it around. See Things I Won’t Touch (1) – Corante
Depends. If the cell is failing internally, it is possible. There are fluorides in there and powerful reducing agents. We are talking a cell that probably will burn the next time it is charged. The logical end result would be LiF and a lot of heat but there shouldn’t be metallic lithium present.
My cells that had failed usually smelt nauseatingly of some vile organic solvent. But the 1% of original capacity was a certain giveaway.
Lithium, son. Nothing else in the world smells like that.
I love the smell of lithium in the morning. You know one time we had a charger on for twelve hours... when it was all over we walked up. We didn't find one of 'em, not one stinkin' dink cell.
The smell, ya know that lithium smell..... the whole room.
You’re not smelling lithium in any form. It is the electrolyte that makes that funky smell. If you can smell it, the cell is leaking. Don’t use it, don’t charge it. Drop it in a jar of salt water for a couple of days to discharge it and then dispose of it properly. Or just give it to the person on the top of your enemies list… J)
I can’t really describe it but it is not a nice smell. It’s chemical and acrid. Almost like smelling salts in a way. If you get a big whiff, it snaps your head back.
If you smell it, it means the body of the battery is split or the cell has leaked. I wouldn’t use it or try to charge it. I was just passing on another warning signal that a cell may be bad.
For those of us that salvage cells, any tip on spotting a bad one is valuable because used cells can be dangerous.
I feel salvaged battery pack cells are safe as long as you can weed out the bad ones. When in doubt about a cell, I mark it with a “?”. When there is something known to be wrong, I write “bad” on it so I don’t get it mixed up somehow.
And if it is below 2.4999V dispose of it safely and don’t even think of charging it. It probably won’t kaboom or burn, or do anything useful but is the few dollars saved worth the risk of burning your house down? Most lithium cells die harmlessly. But some don’t.
And if you can smell it, don’t even think about charging it - dispose of it safely.
I am currently test two cells that had about 1.5v each. I labeled them as bad and don’t intend on using them because I have plenty of cells. I am just doing some research to see what can be done.
At first they wouldn’t take a charge. I had to “bump” them up to over 2v for my I4 to even start to charge them. They got VERY hot so I had to pull them off the charger and let them cool down a few times. Eventually (several days of careful charging) I was able to get them up to full charge. Took much longer than normal and heat was an issue.
I have left them sit for a couple of weeks now and will check the remaining voltage.
One of the cells charged up to 4.2v and the other to 4.18. The 4.2 one is now at 4.18 after a few weeks. The 4.18 is now at 4.03v.
I believe the 4.2v battery may be good enough to use. They are red Sanyos and in the past they have proven to be very well built and robust batteries.
I think I will pitch the 4.03v cell as it is not holding a great charge but the 4.18 cell will be getting further tests to see just how good it still is.
My findings in the past have shown that dead cells (way under 3.0v) can not only be brought back into service but sometimes show no negative effects.
18650s are tougher than some people think and voltage is not the end all and be all of telling how good a cell is.
In general, under 2.5v means a bad cell, I agree with that. In general but not always. I had two red Sanyos from my Toshiba laptop that were 0v and I managed to charge them and I still use them. They have proven to be reliable and have decent capacity. No real difference between them and my other laptop pulls.
GET RID OF THEM… NOW! When a cell voltages falls below the safe level and they are recharged, the cell chemistry can become unstable. It makes the susceptible to spontaneous, unprovoked combustion at anytime, even when just sitting on the shelf.
I wouldn’t worry about them. The guy had to do un-natural acts to even get the charger to accept them. Remember, every laptop has at least half a dozen 18650 cells in them and laptop batteries seldom immolate their owners.
Simple rules: never use them in lights that have series connected cells. Never use a cell that measures less than 2.5V. Never parallel unmatched cells or cells that are at different levels of charge. Use a decent charger. Only use brand name cells. Any cell with “fire” in the name is not to be trusted. I’ve never heard of a problem with cells that are used under these conditions.
