Tenergy NiMHs are pretty tough batteries.

I had a meltdown yesterday. I use a 3AA or 3AAA battery holder, to test LEDs and drivers before hand. I just solder a lead on both ends of the battery holder and then I can touch them to a led or driver, for testing. It works well, except....

I always just leave the battery loaded holder on the table top, in the garage, when I'm working. Yesterday, it was the 3AAA holder loaded with Tenergy NiMHs. I tested a led and then tossed the holder over to the far side of the bench and went back to work. Somewhere about 10 minutes later, I thought I smelled something, but I went on working. Shortly after that, I definitely smelled plastic burning and you know that moment where 1+1 equals Oh Sh*t!, well I looked over and the battery holder was melting before my eyes. I mean it was flat out melting onto the table and the plastic was running down.

If you don't know what temperatures these holders melt down at, let me just say "butane torch" temps. So, what is my first instinct? Yep, to pick up the holder by the wires, to get them apart. Dumb! Then I went to the tool box and grabbed a pair of cutters and cut the wires. They had welded together.

Here's the thing, The outer plastic wrap had melted off the batteries. I could not touch them. I figure the internal temps were well over 300F and probably closer to 400F. It took about 20 minutes to be able to touch them. Not one of them leaked or blew up. Not one bulged, or was misshapen. Now that is a testament to the NiMH battery and to Tenergy, who I always felt were junk. I did not test them. I tossed them. I would not try to use them again, after that ordeal.

I wish I could say I have learned a lesson, but an hour later, I was going to toss down my 3AA holder, just as I had with the 3AAA. I thought better of it, but in a day or two, I will have forgot all about this. This is why I do not use Li-ions.

A bit scary, that, no? Nice test, too bad you weren’t testing. Would’ve been interesting to see if the batteries would resume life as though nothing had ever happened. And yes, that’s a great testament to the NiMh Chemistry and a plug for Tenergy’s that might help you get some freebies to continue your work. :wink:

Ah, yeah, aren’t you super glad those weren’t Li-ions?! Or IMR’s? I just got a couple of 26650’s that have an 18A rating, scares me just looking at em.

Good thing you’re ok, no fires or anything. ^ you being watched over? :slight_smile: ^

Good to hear nothing worse happened, it could have been messy especially if you left and forgot about them.

I find them to be fine in normal use, they feel a little heavier than other NiMH batteries though and are a tiny bit fatter as well. Although mine always get neglected in favor of Evoltas and eneloops.

lol got lucky you were still sitting there, who knows what could have happened if you walked away for dinner or go to bed.

Howly crap :open_mouth: Pics or it didn’t happen :bigsmile:
Nah, joking aside, glad nothing more serious happened to these batts or to you :weary: Anyway, I’d say these batts are good enough, quite sure cheaper made ones would leak or… who knows :expressionless:

It’s amazing how much energy is in these little AAA cells. I once made a dummy AAA cell from a ‘dead’ carbon zinc cell so I could run a 14500 in a 2AAA light. I soldered on the strip to short the cell and set it aside thinking it will be fine. A few minutes later I picked it up and dropped it almost immediately. It was hot! This was a dead carbon zinc (under 1V when I started). I managed to heat up to about 70C before giving up the ghost and cooling down.
If O-L had shorted a Li-Ion pack, the result would have been different; it would not have taken 10 minutes, and it probably would not have melted the holder. The wires would probably have de-soldered themselves before enough heat occurred to melt the holder. The springs might have melted too since they are steel.

So going forward.... if we want to know what will burn or explode, we just send it to Old-Lumens and have him work with it! ???

I can see the sign in the front yard now....

FREE OVERCHARGE TESTING!!! CALL XXXXXXX!!!

Glad you're ok.... we can't afford to lose our "Top Modder!"

Dan.

I’m not a fan of their 18650s (just not enough oomph for me) but their D nimh are incredibly powerful, if you can tolerate the time it takes to charge them.

I wish you’d been taking a video when all this happened 0:)

I don’t own Eneloops yet because I wanted to learn about NIMH battery use and abuse, and charging, on the cheap, and use those cheap ones for keeping in my car trunk at desert temperatures. My Tenergy batteries seem good for that use and abuse.

I’m still waiting for an Eneloop sale to fill my household and EDC lights.

So the wires actually welded themselves together?

I'm glad your ok and yes for all our sakes stay away from Li-ions. Scaru may be able to solve this. For those that have been following his thread on putting an operating system on something that does not want it, (I'd hate to think how many days people have, worked on this) now has an operating system installed but no wireless. When he gets this sorted I'm sure that scaru would be more than capable of building a wireless battery holder for Mr Lumens.

The ends had solder on them. The solder is what welded them together.

WOW there is your next DIY project, making u a soldering iron from batteries and wire :wink:

Ok, that makes a lot more sense. If you're looking for something to use in the future you could just take a bit of shrink wrap tubing and put it on the wire. Pull it off the end of the wire when ever you need to use it.

Safety? Naw, that’s not in the true modding spirit!

Tongue OutTongue OutTongue Out Innocent

I woulda tried to use them again. Maybe even do a few cycles to see what’s left of it.

Holy Moly. The same thing just happened to me. I have a battery holder with a cheap UltraFire 18650 (it came free with a light) that I was using to test LEDs. When I set it aside, the positive lead must have shorted on something, because when I went to use it again this is what the red lead looked like.

It’s an accelerated life test for wire insulation. :smiley:

Wow !

I think I speak for everyone here in expressing relief that nothing serious happened.

My testing setup involves tabs on the end of the cells (2 AA alkaline in series) that need a magnet to compress them and complete the circuit. When not in use, the magnets are an arm's length away.

That puddle 'o plastic would have been quite a sight to see, however...

Truthfully,

  • Protected Li-Ion’s would have “Protected” themselves, and you’d still have three working cells and a non-melted battery holder.
  • Un-Protected IMR would have vaporized the wire, and you’d have to solder a new wire to the battery holder.

With quality Li-Ion cells, this would have been a non-event…

The real lesson here isn’t about NiMh or Li-Ion or batteries in general - its about being careful with things.

PPtk