Spring contacts + and - of a AW IMR26500 Battery, then CATCHES ON FIRE

[SilverFox]

Re: AW "Protected" Battery CATCHES ON FIRE *pics updated*

Hello SmurfTacular,

I am glad you were able to figure out what happened. Now that the pictures are up, I will move this over to the Smoke and Fire section.

Tom

 

[kramer5150]

Re: AW "Protected" Battery CATCHES ON FIRE *pics updated*

Yikes that spring is WAY too long. It wouldn't take much at all for it to bend over and touch +B to -B. Don't forget the mag body tube is -B.

There is a mechanical engineering formula for helical spring stability. I forget the details of it. But in essence, a spring X long in the uncompressed state that you wish to compress to Y length, needs to be Z diameter in order to avoid buckling under load. The more the spring is compressed, the more prone it is to "pop" out sideways and become unstable.

a better solution is a dummy spacer.... brass bar stock pressed into wood dowel cut to length. Pics below show a spacer to adapt 1x26650 to 2x26500 length.

 

[jasonck08]

Re: AW "Protected" Battery CATCHES ON FIRE *pics updated*

That spring looks like the one that use used for the stock maglite bulb holder assembly... am I right?

What type of bulb were you trying to drive with the two cells?

 

[SmurfTacular]

Re: AW "Protected" Battery CATCHES ON FIRE *pics updated*

Dummy bar is a good solution. I'll consider it. But what I will most likely do is find a tapered spring and hot glue it to the plastic switch, then solder a wire from the negative terminal of the switch to the spring.

That spring looks like the one that use used for the stock maglite bulb holder assembly... am I right?

What type of bulb were you trying to drive with the two cells?

YES! Yes it is. You are right. I have tons left over from all the mag mod's I have done in the past, thought it would be a great idea to recycle them. obviously, not so good of an idea.

I planed on driving a P7. But at the time I didn't cut off the switch tower.

 

[gswitter]

Re: AW "Protected" Battery CATCHES ON FIRE *pics updated*

Could you change the thread title to something a little less misleading?

How about "I dead-shorted an AW IMR 26500 and it vented"?

 

[flashfiend]

Re: AW "Protected" Battery CATCHES ON FIRE *pics updated*

Could you change the thread title to something a little less misleading?

How about "I dead-shorted an AW IMR 26500 and it vented"?

+1

 

[Chauncey Gardner]

Re: AW "Protected" Battery CATCHES ON FIRE *pics updated*

Yikes that spring is WAY too long. It wouldn't take much at all for it to bend over and touch +B to -B. Don't forget the mag body tube is -B.

There is a mechanical engineering formula for helical spring stability. I forget the details of it. But in essence, a spring X long in the uncompressed state that you wish to compress to Y length, needs to be Z diameter in order to avoid buckling under load. The more the spring is compressed, the more prone it is to "pop" out sideways and become unstable.

a better solution is a dummy spacer.... brass bar stock pressed into wood dowel cut to length. Pics below show a spacer to adapt 1x26650 to 2x26500 length.

I like Kramer's simple, effective (& home made) spacer method better than the spring setup you are trying to use, Smurftacular. I'd think you'd get a lot of battery rattle even if it hadn't gone .

Keep the mods & adventures coming, always enjoy 'em .

 

[cernobila]

Re: AW "Protected" Battery CATCHES ON FIRE *pics updated*

Could you change the thread title to something a little less misleading?

How about "I dead-shorted an AW IMR 26500 and it vented"?

Yes please......

 

[SmurfTacular]

Re: AW "Protected" Battery CATCHES ON FIRE *pics updated*

Alright, I changed the title. At the time, I thought they where protected Li-Ion cells.

 

[Niconical]

Re: AW "Protected" Battery CATCHES ON FIRE *pics updated*

Alright, I changed the title. At the time, I thought they where protected Li-Ion cells.

The title is still "AW IMR26500 Battery CATCHES ON FIRE...."

Anyone skim reading that, as so many casual browsers do when researching a product, will take away from that "hhm, better steer clear of that AW brand, they catch fire".

The requests for you to change the title were more along the lines of specifying that it was user error rather than a technical fault related to the brand of battery, protected or otherwise.

 

[SmurfTacular]

Re: AW "Protected" Battery CATCHES ON FIRE *pics updated*

The title is still "AW IMR26500 Battery CATCHES ON FIRE...."

Anyone skim reading that, as so many casual browsers do when researching a product, will take away from that "hhm, better steer clear of that AW brand, they catch fire".

The requests for you to change the title were more along the lines of specifying that it was user error rather than a technical fault related to the brand of battery, protected or otherwise.

My intent in this thread was not to inform people that AW makes dangerous batteries, and to steer clear of them. If you felt this way, I'm sorry, I didn't mean that.

I'm now aware that this is completely user error. And that these batteries are not defective. And the reason why they caught fire was because the spring made contact with + and - with no resistance.

This seems to be a unanimous opinion, I hope the new thread title pleases everyone :thumbsup:

 

[AW]

Hi SmurfTacular,

The flame you saw may not come from the cell because the chemistry is not known to vent flames. I believe it is the burning of the missing adhesive plastic top cover resulting from the short. The 60+ Amp released from the ' direct short ' will heat up the plastic material above flash point and started the flame. I still remember I could started a camp fire by rubbing a 9V battery against a pad of steel wool when I was a kid. A few amps on the ' right ' material will start a fire. So please be careful when using these powerful IMR cells.

Best Regards,
AW

 

[Popsiclestix]

Re: AW "Protected" Battery CATCHES ON FIRE *pics updated*

There is a mechanical engineering formula for helical spring stability. I forget the details of it. But in essence, a spring X long in the uncompressed state that you wish to compress to Y length, needs to be Z diameter in order to avoid buckling under load. The more the spring is compressed, the more prone it is to "pop" out sideways and become unstable.

I think it was something like if your free length > 4 times the diameter you need to support the spring. I don't recall the derivation of it though.