My Fenix L2P just exploded!?!?!?

[tdhg566]

or more precisely, the rubber cap protecting the switch blew off. It was bizarre. No I'm not modding it or overloading it or doing anything cute. I'm using Maha PowerEx 2500 NiMH batteries, bought last year, charged in a Maha charger. The flashlight had been running for about an hour when I went to turn it off. I felt this pliable rounded bubble on the end. The bubble was so large (maybe 1/2" tall) that I couldn't press the switch. While I was trying the rubber cap exploded out of the end. I took it apart but can't see any evidence of battery leakage or internal damage to the light. I charged the batteries again, replaced the cap, and the light seems to work. I'm on the road and don't have any equipment with me, so I can't really test either of the batteries.

Anyone else heard of such a thing, and/or what might be going on with the batteries? I have spare batteries I can use until I get home if necessary. Other than just putting the two batteries in one of my testers (I have both the BC-900 and the C9000 chargers), what else should I look for?

 

[Sir Lightalot]

That's odd... the batteries may have vented but that's pretty rare. did you see any residue or black dust in the light?

 

[Gunner12]

I've heard some batteries release gas when things happen. I don't recall what thing though. I don't recall it being too dangerous.

 

[FloggedSynapse]

hm, well, Fenix flashlights have long been known to occasionally develop goiters on the tail clicky. Especially with nimh batteries - I think they can release hydrogen gas and there's no place for it to go in these water tight lights.

I've got an L2D I use as a lamp, tail standing. I can tell when one set of nimh batteries is dying because often the light will suddenly tip over as the bottom swells. Need to unscrew the back bit and push the hernia back in

 

[StarHalo]

Yup, that's a vented battery. One of the batteries has a defect and/or there was too large a disparity in the charge between the two. Don't use those two batteries again - throw them away immediately (the gas vented from lithium batteries is extremely toxic, and they'll almost surely vent again since any defect would still remain).

Make sure everything is okay with your charger before using rechargeables again - fully charge another set and then meter them. Use primaries until then, preferably name brand US or Japan made cells; cheaper batteries are usually the culprit when it comes to venting.

 

[Ctechlite]

Yup, that's a vented battery. One of the batteries has a defect and/or there was too large a disparity in the charge between the two. Don't use those two batteries again - throw them away immediately (the gas vented from lithium batteries is extremely toxic, and they'll almost surely vent again since any defect would still remain).

Make sure everything is okay with your charger before using rechargeables again - fully charge another set and then meter them. Use primaries until then, preferably name brand US or Japan made cells; cheaper batteries are usually the culprit when it comes to venting.

The OP is using NiMH batt's...

There are a couple of other threads about this issue. I can't recall the gist of their answers but if you have a search you may get lucky and find what you are looking for.

 

[Ctechlite]

Found one...
https://www.candlepowerforums.com/threads/107585

 

[DM51]

This is a battery issue, so I am moving it into the 'Batteries Included' section.

 

[Khaytsus]

Nobody has said this yet.. Throw the batteries away. Use it as an excuse to get Eneloop. They're 8 for $13 at Circuit City.

 

[Bullzeyebill]

This is a battery issue, so I am moving it into the 'Batteries Included' section.

It is also a recurring issue with the Fenix AA lights using NiMh batteries. Not really sure this is classic battery venting that signals a problem with a battery or batteries. May be a Fenix design issue. Several threads and posts have shown up pertaining only to Fenix having such issues. I am not questioning your move to Batteries section, as problem is certainly battery related.

Bill

 

[Bullzeyebill]

Nobody has said this yet.. Throw the batteries away. Use it as an excuse to get Eneloop. They're 8 for $13 at Circuit City.

People are having the same issue using Eneloops with Fenix AA lights.

Bill

 

[UnknownVT]

Found one...
https://www.candlepowerforums.com/threads/107585

That's a good thread - we recently discussed this -

The Fenix L2x series share the same head as the L1x series,
and the heads are spec'd to go as low as about 0.9V before dropping out of regulation.

Now ~ 0.9V is fine for a single battery -
but is too LOW for 2 batteries in series.

Caveat - most people use 2x NiMH in the Fenix L2x fine -
but one should not allow the light to continue discharging as soon as dimming of the light is noticed - especially in the Low and Medium modes -
that may well be over-discharging the batteries - to the point where one battery might be reverse charged - this can lead to venting/gassing of that battery.

Apparently this is aggravated if the two batteries are not well matched in capacity or state of charge.

So in other words DON'T try to squeeze every last drop of charge out of the batteries or leave the light on unattended -
instead stop as soon as dimming is noticed,
then there probably would not be any problems -

please see this thread -

Unevenly drained batteries
specifically starting with Post #19 , (#20 , #21 , #22 , #25 , #27 )

 

[chanamasala]

Do those pellets in Streamlight Proply 4AA neutralize battery gas? What are they called? Does anyone sell those pellets?

 

[Mr Happy]

Do those pellets in Streamlight Proply 4AA neutralize battery gas? What are they called? Does anyone sell those pellets?

I'm not sure. But NiMH batteries should not be giving off gas. If they do they are being damaged.

 

[DM51]

Posts #10, #11 & #12 (Bullseyebill and UnknownVT) seem to be the important ones here, getting to the cause of this.

As they have said, this seems to be not only a battery issue, which I assumed it was, but also it seems to be very specific to the Fenix L2x lights when used with NiMHs.

I am very open to members' suggestions as to which section this thread belongs in. Maybe it should stay here for a while, and we'll see how it goes.

The important thing is that owners of these particular lights should be made aware of this potential problem.

 

[tdhg566]

This is OUTSTANDING folks. Thanks for the hints at other threads to study. I certainly will, and I appreciate your patience in that I didn't know enough about the problem to find the threads ahead of time.

These are brand new Maha PowerEx batteries. And it's not just these two batteries, because I always travel with two L2P flashlights and the second lite is doing the same thing this morning.

One reason this came as such a surprise to me is because my L1P lights never experienced this problem, no matter how long I ran them.

I also may have contributed to the problem by using sealer grease on the threads, further preventing any gas from escaping.

Guess I may have to get L1P bodies and be content with single cell AA lights for travel purposes, OR only use non-rechargable batteries in these particular lights.

 

[zipplet]

I believe the reason it seems to be specific to the fenix L2x lights is that the Fenix L2x lights are very popular, and one of the only high current draw series of lights that use 2xAA *and* have a rubber tailcap that can balloon if the pressure builds up in the light.

If this happens in another 2xAA light without a rubber tailcap constructed in the same way as a fenix, you wont notice the pressure unless it's so high that the tailcap shoots off when you unscrew it

 

[UnknownVT]

As they have said, this seems to be not only a battery issue, which I assumed it was, but also it seems to be very specific to the Fenix L2x lights when used with NiMHs.

NO! This is potentially a problem for any multiple cell light -
(and not just the Fenix L2x) -
any time cells are discharged beyond their capacity - this is often the case where cells are not matched in capacity and/or state of charge the lower of the batteries can be reverse charged - which leads to possible venting/gassing.

The way to prevent this is either have a circuit that will cut off if the voltage drops below about 2 volts for 2 cells - but that might not be so acceptable since this will shorten the runtime often leaving cells with plenty of remaining capacity -
or for the user to simply TURN OFF the light when dimming is noticed - especially if in the low or medium modes - just STOP - as opposed to trying to squeeze every last drop of charge out of the batteries - because you will - that is every last drop of LIFE from the batteries - ie: batteries can potentially be damaged.

3 cell lights may have even higher potential for problems since most of these light tend to use only a resistor to drop the voltage to Vf - therefore there is no cut off voltage only when one of the cells stops conducting - by then it may be too late......

Remember this is no where near as catastrophic as multiple lithium CR123 lights that have literally exploded.......

Exploding Batteries

ROAR of the Pelican (CR123 Explosion during use, firsthand account ...

 

[DM51]

I think most people are aware by now of the potential problems with Lithium primaries and Li-Ion rechargeables over-discharging in multi-cell applications, but this particular problem with NiMHs is something I have not come across myself before, and it may be new to others as well.

 

[Mr Happy]

I believe it is well known among the "techies" on this forum that NiMH in a multi-cell application should not be drained right down to the last drop due to possible damage from reverse charging of the lowest cell(s).

For many people this damage would go unnoticed at first, until they started getting reduced run time after a few charges. It is only the completely sealed flashlight body of the Fenix that makes it so visible.

I think it warrants a general note in a FAQ somewhere that it's always best to stop and recharge NiMH packs or cell groups before they are completely empty to avoid damage and reduced life, especially in flashlights designed for alkaline batteries.