Anybody ever experience this?

hburner · Apr 2, 2007

This happend at the end of the charge with a set of Duracell 2650 rc's. The light never even got warm. I did not even notice because the light was on lying on my chest. It had been on for about 15-20 min. I unscrewed the bezel the tailcap went down, although strecthed a bit. The batteries had not leaked and were not even warm. Does anybody know what caused this? hb/

D@rk Messenger · Apr 2, 2007

Batteries release hydrogen gas. Since the unit is entirely sealed, the gas tried to escape through the rubber boot causing a ballooning effect.

Tightgroup · Apr 2, 2007

I second Dark's opinion, glad you didn't get hurt.....

Todd

elgarak · Apr 2, 2007

Definitely outgassing batteries. Hydrogen, as mentioned.

However, should not happen during normal use.

hburner, what did happen, exactly? You're somewhat hazy on the details.

Did you take the batteries hot off the charger, into the light, ran for 15-20 min, and blow? If so, which charger did you use (settings, if applicable)?

Chao · Apr 2, 2007

It was happened in my L2P before, I just then prevent using old NiMH batteries or make sure both two NiMH batteries have same juice, so far, it never happen again.

SuperNinja · Apr 2, 2007

It tried to fart. :eeksign:

hburner · Apr 2, 2007

The batteries had been in the light for 3 or 4 days and had been used off and on, I was getting ready to recharge them but I was just going to run them down first. The was noticeably dim for being on high. The cells are just a few months old and have only seen maybe 3 or 4 cycles.

elgarak · Apr 2, 2007

hburner said:
The batteries had been in the light for 3 or 4 days and had been used off and on, I was getting ready to recharge them but I was just going to run them down first. The was noticeably dim for being on high. The cells are just a few months old and have only seen maybe 3 or 4 cycles.

Ah. Over-discharge, I would gather. You ran the batteries to far down as was good for them.

Recommendation: Do not run down the batteries in the light. Could be tricky, practically, to get the right moment where the batteries should not be used. But the dimming should have been the warning to NOT discharge them further.

The Fenix is a nicely regulated light. During the batteries discharge, the regulation pulls a larger current from the batteries. When the regulator cannot supply the set current to the LED, i.e. the light noticeable dims, the batteries are damn near empty. But the regulator still tries to get a nice current out of the batteries. Result: Very likely over-discharge, with venting, as you experienced.

Most people claim that you can charge NiMH without discharging them first.

matrixshaman · Apr 2, 2007

Was this the first use of these batteries? I didn't know NiMH like these would cause that much gas to be released. Silverfox or some of the other battery pro's here might know more about this but I think this is the first time I've come across NiMH batteries doing this. I've actually just recently started using rechargeable AA's again so it will be good to hear more about this.

mmmflashlights · Apr 2, 2007

Makes me glad to have a Lightning Pack 4000N charger which can be set to discharge the batteries before recharging them.

elgarak · Apr 2, 2007

matrixshaman said:
Was this the first use of these batteries? I didn't know NiMH like these would cause that much gas to be released. Silverfox or some of the other battery pro's here might know more about this but I think this is the first time I've come across NiMH batteries doing this. I've actually just recently started using rechargeable AA's again so it will be good to hear more about this.

Easily. That's not much gas. Gas takes much more volume than a liquid. Besides, it has nowhere to go but into the tailcap.

I doubt that the batteries can still be used, though.

VidPro · Apr 2, 2007

agrees with ELgark. dont try and "Cycle" the batterys in a SERIES light. hey use the light ok, but if your intention was to discharge the battery , before recharging it, in a light that CAN potentially work with 1V, your going to indcur a reverse charge.

also that could have occured just from expanding air, in a sealed confinement, curcuit heats, battery heats, air heats it expands a bit. but then it wouldnt happen rapidly

psyrens · Apr 2, 2007

Reading the thread I came across with this question.
Does NIMH battery need to be discharged before recharge?

VidPro · Apr 2, 2007

psyrens said:
Reading the thread I came across with this question.
Does NIMH battery need to be discharged before recharge?

need, no, but it dont hurt once in a while.
It would be preferable to do that on a charger designed to do it, or in a single cell light, or in a 2 cell light that stops operating/discharging at about 1.3v or HIGHER.

Patriot · Apr 2, 2007

holy cow! I've never seen that before. Now I know.

Toohotruk · Apr 3, 2007

I've always had the understanding that NIMHs should be "broken-in" by charging them, then running them out of juice for 2 or 3 full cycles before just "topping" them off anytime you want. I thought that would kind of "set" the memory, so you will get the longest life between charges possible...is that true? It has worked well for me over the years, my NIMHs have always had very long runtimes after doing this to them, as well as a very long service life...have I been doing it wrong all this time? I've never had any problems whatsoever using this technique...have I been asking for trouble and just been lucky all this time?

oo:

I always try to "pair" them up (at least the ones I will use in pairs, like the AAs I use in my digital camera)...for instance, I take a pen and mark pairs of batteries, so I always use the same pairs of batteries together, so they both have been charged and used an equal amount of cycles...both charged, or "topped off" and both drained at the same time, so they basically have identical "lives." Just seemed to be a wise thing to do...but I'm not 100% positive this is the right way to go about things.

I really don't remember where I got this advice, but I would like to know what the general consensus here on CPF is...what, if anything, do you all do to "break-in" your new NIMHs?

fenix_fan · Apr 3, 2007

This happened to my L2P some time ago.

See: http://candlepowerforums.com/vb/printthread.php?t=107585

This thread has some good answers.

xiaowenzu · Apr 3, 2007

Next time have a pin handy when it happens so you can POP IT! :lolsign:

hburner · Apr 3, 2007

I am going to check voltage on those cells and the rehcarge them just to see what I get, I will post my findings.

Pellidon · Apr 3, 2007

Toohotruk said:
I've always had the understanding that NIMHs should be "broken-in" by charging them, then running them out of juice for 2 or 3 full cycles before just "topping" them off anytime you want. I thought that would kind of "set" the memory, so you will get the longest life between charges possible...is that true? It has worked well for me over the years, my NIMHs have always had very long runtimes after doing this to them, as well as a very long service life...have I been doing it wrong all this time? I've never had any problems whatsoever using this technique...have I been asking for trouble and just been lucky all this time? oo:

I always try to "pair" them up (at least the ones I will use in pairs, like the AAs I use in my digital camera)...for instance, I take a pen and mark pairs of batteries, so I always use the same pairs of batteries together, so they both have been charged and used an equal amount of cycles...both charged, or "topped off" and both drained at the same time, so they basically have identical "lives." Just seemed to be a wise thing to do...but I'm not 100% positive this is the right way to go about things.

I really don't remember where I got this advice, but I would like to know what the general consensus here on CPF is...what, if anything, do you all do to "break-in" your new NIMHs?

I think the cycling is to get the upper limit of the cell broken in. They gain a little capacity each cycle for the first two or three. Then you get close to the stated capacity. I try to keep mine paired up but I don't lose sleep over it if it doesn't happen.

Anybody ever experience this?

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