problem with 2500mah Energizer NiMHs

[Jaz]

Sorry if this has come up before:
I"m using Energizer nimhs in an L2D-CE. These are the problems:

A) On turbo the runtime is only about 1hr 40min instead of 2.4hrs as Fenix claims it is.
B) When the batteries have almost run out and the regulation is going they start letting out a gas which literally inflates the tailcap and stinks when the torch is unscrewed. Is it normal for the Energizers to do this?

I'm thinking of getting some Eneloops if I can - anyone know if they'll solve these problems? The first I'm not too concerned about, but the second I kind of am.
Thanks in advance.

 

[Power Me Up]

Sorry if this has come up before:
I"m using Energizer nimhs in an L2D-CE. These are the problems:

A) On turbo the runtime is only about 1hr 40min instead of 2.4hrs as Fenix claims it is.

Unfortunately, the 2500mAh Energizers have a bad reputation for developing high self discharge after only a relatively small amount of usage.

If you're not using them straight off the charger, you're probably running into the high self discharge problem. They can literally get to the stage of losing all of their useful charge within a couple of days or less.

B) When the batteries have almost run out and the regulation is going they start letting out a gas which literally inflates the tailcap and stinks when the torch is unscrewed. Is it normal for the Energizers to do this?

If the cells are poorly matched (i.e. one cell has a higher capacity than the other or if one self discharges quicker than the other) you can end up in the situation where one cell is still going strong whilst the other is completely flat and even being reverse charged.

I'd suspect that this is the case here - particularly as the L2D uses the same head as the L1D and will keep running until the voltage under load is down to 0.9V - much too low for a pair of NiMH batteries. I'd say that one of your cells is being reverse charged which is causing it to vent.

I'm thinking of getting some Eneloops if I can - anyone know if they'll solve these problems? The first I'm not too concerned about, but the second I kind of am.

Yes, they should help a lot. Although you probably won't get 2.4 hours out of them (since Fenix is probably testing with good 2500 mAh cells versus the 2000 mAh of the Eneloops) you'll probably get about 2 hours.

Eneloops tend to be very well matched so they should be less likely to have one become reverse charged when used in pairs, but since the L2D discharges to such a low voltage it's still possible - I'm pretty sure that I've seen reports of venting in an L2D with Eneloops in this forum, but I think it was on low instead of turbo.

Probably the best reason for going with the Eneloops is to remove self discharge as a problem - definitely worthwhile in any case if you're not using the light much and particularly when compared to the dodgy Energizers!

 

[lumenal]

Do you check your voltage with a DMM?

And do you have any type of a battery tester?

These 2 items are almost a requirement if you plan to use rechargeable cells, in order to monitor cell condition.

As reported above, alot of 2500mAh cells have died early deaths, and Energizers are the most prominent.

Personally, I use my L2D regularly, running Sony 2700s or Energizer 2500s. Never had a problem with either set of cells.

In fact, my 2500s have held a charge of 4 or 5 months at a time - no sign of a high self-discharge rate. And they are almost 2 years old, and made in Japan.

Another thing - do you drop your light alot?

Do you practice juggling with your NiMH? (Just kidding).

NiMH can be fragile, especially the higher capacity cells.

Recycle the vented cells and get the Eneloops.

 

[Jaz]

Lumenal, no, I don't have any sort of battery tester (or even know what a DMM is ). Really I don't think it's worth it for the amount I'll be using the batteries.

If the cells are poorly matched (i.e. one cell has a higher capacity than the other or if one self discharges quicker than the other) you can end up in the situation where one cell is still going strong whilst the other is completely flat and even being reverse charged.

I'd suspect that this is the case here - particularly as the L2D uses the same head as the L1D and will keep running until the voltage under load is down to 0.9V - much too low for a pair of NiMH batteries. I'd say that one of your cells is being reverse charged which is causing it to vent.

Sounds like it could be. I didn't notice the problem with my Jetbeam C-LE, which just uses one AA.
I think I'll get some Eneloops.

Thanks to both of you for the replies and advice.

 

[Mr Happy]

I think what people haven't made clear to you here is that when you use rechargeable batteries in an L2D you should stop and recharge immediately you detect it's dropped out of regulation, if not before. Running beyond that point, especially if the tailcap inflates, is damaging to the batteries. Eneloops will be damaged just the same way if you let that happen to them.

Here the light is at fault, not the batteries. The light is not designed to protect against damage to rechargeable batteries. When you get your Eneloops, you should time how long it takes to fall out of regulation, and then always recharge the batteries before this time is up so you never get a ballooning tailcap or horrible smell. With Eneloops you can keep a spare set of cells on standby and put fresh ones in the light while the others are on charge.

 

[PlayboyJoeShmoe]

Can't stop myself from responding no matter how I try!

LSD NimH (Eneloops, Hybrids etc) will run my 2AA Garmin GPS every bit as long as 2500 regular NimH EVER did. I have about 20+ 2500 in a dead pile.

Every LSD NimH I've gotten are still going strong.

I would not worry about reduced runtime and instead be happy!!!

 

[whippoorwill]

Can't stop myself from responding no matter how I try!

LSD NimH (Eneloops, Hybrids etc) will run my 2AA Garmin GPS every bit as long as 2500 regular NimH EVER did. I have about 20+ 2500 in a dead pile.

Every LSD NimH I've gotten are still going strong.

I would not worry about reduced runtime and instead be happy!!!

+1

 

[Jaz]

Good to here about the NiMH runtimes.

I think what people haven't made clear to you here is that when you use rechargeable batteries in an L2D you should stop and recharge immediately you detect it's dropped out of regulation, if not before. Running beyond that point, especially if the tailcap inflates, is damaging to the batteries. Eneloops will be damaged just the same way if you let that happen to them.

Here the light is at fault, not the batteries. The light is not designed to protect against damage to rechargeable batteries. When you get your Eneloops, you should time how long it takes to fall out of regulation, and then always recharge the batteries before this time is up so you never get a ballooning tailcap or horrible smell. With Eneloops you can keep a spare set of cells on standby and put fresh ones in the light while the others are on charge.

That clears things up, thanks. I'll take your advice and not try to run the light till it's completely dead. (Seems strange that you can't though :huh:.)

 

[Mr Happy]

That clears things up, thanks. I'll take your advice and not try to run the light till it's completely dead. (Seems strange that you can't though :huh:.)

Oh, you can...if you are using alkalines. You can run those until they are completely exhausted. It's with rechargeables only that you should replace them before the light dims. There is nothing to lose there of course, because you can recharge them 100's of times. You are not wasting anything by swapping them out before they are completely dead.

 

[lumenal]

That clears things up, thanks. I'll take your advice and not try to run the light till it's completely dead. (Seems strange that you can't though :huh:.)

Jaz - a DMM is a Digital MultiMeter, which, among other features, has a voltmeter which allows you to check the voltage of your cells.

They can be had for as little as $2.99 at Harbor Freight Tools (on sale), and they work well for that endeavor.

As soon as I notice dimming on my L2D, I change out the NiMH cells. I didn't realize you were draining yours down to nothing! Ouch! Not good for those rechargeables!