eneloops releasing gas

[ChrisXX]

Hi,

since 2007 I'm an impressed owner of a Fenix L2D, which I used extensively (three sets of batteries in a row) the first time last week.
I'm using eneloops, which are still quite new. (Maybe 2-3 cycles)

I were using the light on turbo mode without any breaks; as it was relatively cold outside the light didn't get hot, so I had no bad feeling about it. The first pair of eneloops worked as I expected it, I used 'em till they dropped out of regulation. The next pair, however, after some usage (could've been about 80% the time the last pair worked) seemed to release gas: The rubber cap expanded like a balloon, although the light was still bright as in turbo mode (didn't drop out of regulation yet). Shocked, I exchanged the pair with another, and again after some time the same happened.


So what was wrong?
I've read mainly that NiMh might release gas during overcharge ...
In some other threads on CPF I've read of problems with cells which seemed to be unable to handle the load ... eneloops were suggested.
As eneloops seem to be quite popular I wonder what the problem is...
Another thread suggested that gas release would only happen as the last reaction during extreme discharge ... which would wonder me as the light was still in regulated mode, and it should (?) drop out of regulation before deep discharging ...
I'm puzzled ...
If they released gas enough to make the cap look like an one inch diameter balloon ... did they loose (much?) capacity (that hydrogen must be missing somewhere )?


Thanks,
greets
ChrisXX

 

[Marduke]

Don't use vented cells. Set them aside and ask Sanyo for replacements.

My guess would by that you're using the turbo mode continuously, which is not the brightest idea. Try using high instead.

 

[jirik_cz]

Probably bad cells, they should handle the load on turbo without problems.

 

[Wicho]

The same thing has happened to me - the way I've looked at it, since there are o-rings involved, it's the air trapped inside the flashlight's body heating up and expanding, not necessarily bad cells. I've had it happen with Sanyo 2700's and eneloops - I doubt I would have that many bad cells.

And we always wondered why Fenix includes the spare tailcap boot...

I could be wrong, though.

 

[Bullzeyebill]

There are other threads about Fenix lights puffing up the rubber tailcap. Seems to be a Fenix issue.

Bill

 

[42]

I've had the same thing happen using Duracell NiMHs in Fenix L2Ds. I experimented a bit and it happened with every set I tried. I wasn't to happy about this and just gave my NiMHs and charger away and chalked it up to experience. Now I use Lithium primaries exclusively.

 

[VidPro]

it's the air trapped inside the flashlight's body heating up and expanding, not necessarily bad cells. .

good point, open light in extreeme cold, insert batteries, and COLD air, heat air with batteries driver and led, air expands.

a enloop is capable of venting and resealing after a vent. but nothing might have vented at all?

take a ballon filled indoors and stuff it outdoors in the cold it shrinks like, like , well we cant say that here

 

[RoyJ]

Yup, happens to every L2D. Mine uses Rayovacs, and the thing balloons every time when the cells are nearly dead.

 

[RobSpook]

...the thing balloons every time when the cells are nearly dead.

I wish my Fenix L1T/L2T had this low battery indicator!

 

[Helmut.G]

this is completely normal, it happend to me many times
the L2D has no protection against overdischarge, and NiMHs put out gas being overdischarged.
Of course this isn't good for the batteries at all, but doesn't mean that the batteries aren't good andit happens in every mode if you run the light long enough

 

[Ray_of_Light]

Ni-MH can produce gas when they are reverse charged, even slightly. Some lights have a protection against polarity cell reversals (Streamlight Jr. LED, Opalec NewBeam), they cut at 1.8 Volt.
Fenix hasn't such a feature and so, in case of unbalanced NiMH cells, one cell may vent.

Anthony

 

[jirik_cz]

It never happend to me with sanyo 2700 or eneloops, but I change batteries when light gets dimm (I use turbo only).

 

[ChrisXX]

Thank you all for your answers.


Maybe the cells where charged slightly different. (I charged them one after another, could this be a problem?) Maybe I'll check the voltages and try to reproduce the gas release.

thank you, greets
ChrisXX

 

[Wicho]

Give 'em some Beano along with their next feeding...er, recharging. :naughty:

That should solve their gassiness.

 

[lyyyghtmaster]

I have 2 L2Ds (a P4 and a Q5) and have run many sets of NiMH (Eneloops and you name it) through both and have never had this happen. In fact, I was kind of surprised to read this thread! But I always shut the light off once I realize it has dropped out of regulation, which may be at most 20 seconds after it actually dropped out.

What my Q5 does do, however, is sing. It sings on Turbo mode only, most (but not all) the time, regardless of which of three tailcaps I try! I assume it's the electronics, possibly interacting with some physical construction detail of the tailcap switch. Oh, well.
:thinking:

 

[Hitthespot]

Yea, I do that from time to time.