I've got a new reason to remove cells from LED flashlights when not in use...

EngrPaul · Sep 3, 2009

I keep running into a situation where I fire up an Fenix LED flashlight that's been sitting in my car for a while, and it's dead. Most recently an E0 bit the dust.

I purposely use lithium primaries so that it will hold up under any weather conditions and be ready to go when needed. Problem is, the lithium cells are outliving the flashlights!

After verifying the cell and connections are all good, that it's a bad head, I dissembled the light to see what's failing. The board was warped! Components fell off and I observed cracks in the PCB, and I don't think it happened when I pushed out the pill.

Evidently the (+) lead of the battery is constantly pressing on the PCB with a spring force. Over time, temperature, and force, the thin board becomes concave inward due to this constant load.

Although I spoiled a chance to return the light for warranty service, I learned something valuable about LED flashlights. If the battery tube has a spring on the (-) terminal, and the (+) terminal of the battery presses on a PCB, remove the battery when stored for a while, especially in hot conditions.

Hope this helps someone else... :candle:

richardcpf · Sep 3, 2009

The main problem here is the heat... it may expanded the battery.

Because lets say you have been carrying a E01 for a year as you EDC, and all this time the battery has been in there however it did not damage the circuity at all...

Im gonne check all the flashlights in my car..

FlashInThePan · Sep 3, 2009

It's not just in hot conditions; I've had the same thing happen to the Fenix P3D in my car...in Alaska. I've seen a few sites that attempt to measure the current draw while a light is off, and based on their measurements, this shouldn't be happening to a P3D after only a year or so. Thanks for mentioning this, EngrPaul; is anyone else having this same problem?

- FITP

rider · Sep 3, 2009

EngrPaul said:
I keep running into a situation where I fire up an Fenix LED flashlight that's been sitting in my car for a while, and it's dead. Most recently an E0 bit the dust.

Maybe you should retitle this "...a new reason to remove cells from FENIX flashlights...", since I've kept various Inova LED lights in cars for years (and our yearly high/low temperatures vary by about 100 degrees, so the in-car temperature swings are even greater), and have never had any type of failure -- and I'd consider the Inovas to be some of the least reliable lights I have.

Fenix sure has a great price/performance ratio, but their longevity is turning out to a bit questionable in my experience.

sparkysko · Sep 3, 2009

I doubt it's from thermal expansion.

With a 70 degree difference (70F inside to 140F hot in the car), the steel casing of the battery will expand 0.001 inches. The flashlight body will also expand, and if aluminum, the thermal expansion is greater than the battery.

Any temp above 140F will nuke most batteries and epoxies. Car temps can easily get to this (I never dare store lipos in a car with the windows closed).

My guess would be that exceeding 140F started breaking down the epoxy in the PCB, causing it to weaken. (I've tried speed curing laminated fiberglass with finishing resin at 180F and it literally smokes at this temperature, although the epoxy isn't completely destroyed).

I'd try storing stuff in the trunk, much cooler.

KD7EIR · Sep 3, 2009

I have never heard of this with any other flashlight. ANY flashlight that suffers damage just from having batteries in it is a piece of poorly designed junk.

Keeping the light in your trunk is not a solution. Most likely when you really need the light, you are not going to want to have to get out, open the trunk, find the light, close the trunk...

If the PCB is breaking down from normal in-car temperatures then it, too, is poorly designed. Modern cars are full of PCB's and I have not heard of them needing to be stored in the trunk to keep them safe.

I am not saying that Fenix is a bad brand, but I would venture a guess that you have a particularly bad sample of their product.

dano · Sep 3, 2009

Never heard of battery spring pressure in combination with potential excessive heat causing any physical failures of PCB boards.

I wonder how widespread this is with the overseas based lights that share components, or is this just an isolated case?

MarNav1 · Sep 3, 2009

EngrPaul said:
I keep running into a situation where I fire up an Fenix LED flashlight that's been sitting in my car for a while, and it's dead. Most recently an E0 bit the dust.

I purposely use lithium primaries so that it will hold up under any weather conditions and be ready to go when needed. Problem is, the lithium cells are outliving the flashlights!

After verifying the cell and connections are all good, that it's a bad head, I dissembled the light to see what's failing. The board was warped! Components fell off and I observed cracks in the PCB, and I don't think it happened when I pushed out the pill.

Evidently the (+) lead of the battery is constantly pressing on the PCB with a spring force. Over time, temperature, and force, the thin board becomes concave inward due to this constant load.

Although I spoiled a chance to return the light for warranty service, I learned something valuable about LED flashlights. If the battery tube has a spring on the (-) terminal, and the (+) terminal of the battery presses on a PCB, remove the battery when stored for a while, especially in hot conditions.

Hope this helps someone else... :candle:

So does that mean more EngrPaul mods? I hope so! :nana:

NE450No2 · Sep 3, 2009

I have some Sure Fire lights that have had batteries in them for 5 or 6 years with out any use and they still "glow in the dark."

I just checked a few of them yesterday.

I recently moved, and a couple of them have been packed in my metal garage [I now live in the country, in Texas ie. it is HOT, and COLD] for almost a year. They are still bright.

WadeF · Sep 3, 2009

EngrPaul said:
and I don't think it happened when I pushed out the pill.

So you removed the PCB, but can't be sure doing so resulted in the cracking?

EngrPaul · Sep 3, 2009

WadeF said:
So you removed the PCB, but can't be sure doing so resulted in the cracking?

The pill pushed right out without any crackling sounds.

If I damaged the board pushing it out, it would have been convex toward the battery.

I've got a new reason to remove cells from LED flashlights when not in use...

EngrPaul

Flashlight Enthusiast

richardcpf

Flashlight Enthusiast

FlashInThePan

Enlightened

rider

Newly Enlightened

sparkysko

Enlightened

KD7EIR

Newly Enlightened

dano

Flashlight Enthusiast

MarNav1

Flashlight Enthusiast

NE450No2

Enlightened

WadeF

Flashlight Enthusiast

EngrPaul

Flashlight Enthusiast

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