Li-Ions and over-heating

[Braka]

First, thanks very much to FlashCrazy for the heat Tests. I'm sorry if it seemed I was ignoring you. Nothing is further from the truth, as I'd stepped aweay for nearly a week because I was a bit irritable, and didn't want to get into post in that condition. Until just now, I was unaware you'd posted those follow-ups, and gain, thanks.

Andy - sorry, I have no idea how it will perform on a single cell.

I recommend you do some research here on the forum using the search function to be able to use those Li ions safely.

I'm sorry, but I was a little miffed that you would automatically assume I had done no research. In fact I had spent, at my best guess, at least 90-120 minutes going through the search functions on this board alone, for terms which seemed germane to the topic. You introduced a topic which
I had not thought of. This does not mean that I hadn't made extensive use of the search function before I bothered anyone with a question; merely that I searched on topics x) and y) but not Z).

Braka.

 

[LED61]

Braka, I'm sorry that my post transmitted negative vibe's. I assure you it was not meant to. My posting tends to be short and consice but also seems a bit cold at times. Sorry for that. I'm glad you did your research, it is actually a necessity before handling these power sources. Go ahead and post and ask any doubts you may have, this forum is a great place and I myself have a lot to learn from other knowledgeable folks here.

Another thing, your questions will never be bothersome to anyone!!

 

[Braka]

Thanks. No harm done.

Braka.

 

[FlashCrazy]

Well guys, thanks to this thread I did more poking around about Li-Ions and safety. From using Li-Poly battery packs in my model airplanes, I already knew about the hazards of discharging the batteries below 2.7v per cell....and about not charging them too fast. But what I didn't know was that these 123 cells only had a 2C discharge rating. My airplane packs are anywhere from 8C to 15C. So if this Hemse light is discharging the cells in 20 minutes, then the current draw on the batteries would be 3C...well over the limits for the battery. This would harm to battery at best, and could cause the battery to swell and violently vent with flames. In a sealed flashlight, this is not good. There's pictures of a guy on the forums that had this happen, and the glass lens shattered and cut him all over his face. Another guy was sick for a week because the glass pieces cut his arms, and the chemicals caused him to vomit for days. The part that really scared me is that any damage caused to a battery by over discharging may not show itself until many cycles later. Something about a dendrite forming in the battery, then eventually causing an internal short, without warning. I just ordered some protected batteries...they're only a couple bucks more. I figure the cost is worth it! Also, flashlights that use more than one cell run the risk of having one of the cells discharging faster than the other. This cell could go way under 2.8v, even to a negative voltage. Then you put the batteries on your charger...that battery gets a huge inflow of current at first. All of this adds up, then one day...BOOM!! I've learned the best scenario is to have a light that uses one cell...and to use a protected cell.

 

[LED61]

Good job!! especially good are AW´s new protected R123´s. The only drawback to protected is, aside from more money, reduced capacity. But for an incandescent light AW´s new protected R123´s are the way to go. Personally I don´t like to handle unprotected Li ions.

Additional research on rechargeable batteries can be done at

www.batteryuniversity.com

 

[FlashCrazy]

Ok, more thoughts in my head. My Hemse seems to go for closer to 30 minutes based on the testing I did before. This was with cool down periods, which I'm sure helped the batteries put out more than they would if I let it run continuously. So, that's about a 2C discharge rate. This seems to be accurate, since my batteries are 800 mAh, but in testing I did with them at a 1000 mA discharge they showed about 550 mAh capacity. Current draw of my Hemse shows 1200 mA, measured at the tail. That's pretty much a 2C discharge rate. All in all, I'm still going to use my Hemse, but only for a few minutes at a time...plus I'll be using protected batteries from now on. I have other lights that draw less current, I'll use those for situations where I need light for a longer period. I'd probably never have a problem with unprotected batteries, since I constantly check their state of charge, don't discharge them too low, and I make sure their voltages are matched when charging them or putting them in a light. But since protected batts are only a couple bucks more, that's the route I'm taking...and I'll still adhere to the same practices that I would do with unprotected batts.
And Braka, you're welcome. I'm always doing runtime tests anyway, and am glad to share the info. Now if I could just break this flashlight addiction!

 

[FlashCrazy]

Good job!! especially good are AW´s new protected R123´s. The only drawback to protected is, aside from more money, reduced capacity. But for an incandescent light AW´s new protected R123´s are the way to go. Personally I don´t like to handle unprotected Li ions.

Additional research on rechargeable batteries can be done at

www.batteryuniversity.com

I ordered some BatteryStation cells from LightHound, just to get them quicker. I did see AW's new cells, they look very nice! I am going to order some of those too, just haven't gotten around to it. How long does it usually take to get orders from AW? Thanks.

 

[ynggrsshppr]

If you're doing runtime tests with a waterproof flashlight you can submerge all or part of the flashlight in a glass of water to keep it cool. I grabbed/stole this little tip from someone else on the forum. I tried it with my Fenix P1, got it to tailstand in a cup filled with cold water. Kept the thing nice and chilly!

 

[NewBie]

Keep in mind, if the outside of the light was 60C, likely, the batteries were even hotter yet, and internal to the cell, even hotter yet inside the cell.

You might also give this thread a look over:
https://www.candlepowerforums.com/threads/106242

IMHO, if you treat the cells properly, you greatly lower the risk.


.

 

[LED61]

Another thing to keep in mind is that, as the manufacturers have admitted that they cannot control at 100% metal particles getting inside a cell during manufacturing, it is a lot easier for greater capacity cells to be short circuited.