Fenix E05 SS acting really weird

So, about a month ago, I asked if there was any way nano oil could be causing a short, because my E05 SS had started coming on whenever the head was attached instead of only when it is fully screwed down like it's meant to. Everyone agreed that nano oil isn't conductive, but for whatever reason after I cleaned out the head and threads with some alcohol, the problem went away (now I think that might have been a coincidence). I reapplied nano oil and everything was still fine - I assumed something must have got in there to cause a short, even though I couldn't see whatever it was.

Fast forward to about a week ago and it starts doing something else. One minute the light is working normally. The next, as I try to cycle through the modes, it just goes dead. So I check the cell with a DMM and the voltage is fine. Try another, fresh cell: still dead. Try primaries: still dead.

So I assume the circuit has just blown somewhere and it needs to be sent back, but the next day I try it again and it works. For about 5 minutes. Then it's dead again.

I repeat this testing process over the course of several days. Each time, the light is fine for a few minutes and then dead. Wait 1-2 days and it works again. Yesterday I noticed that sometimes it doesn't respond to an Eneloop, but if I insert an Energizer Lithium (newish, showing 1.72v) that seems to wake it up. But then switch back to Eneloop and it stops working again. Yesterday, I managed to get it to start/stop a few times, until it eventually just died completely and the Lithium couldn't revive it. Sometimes it would run on the Eneloop for a few seconds, but usually not.

Today, I tried an Eneloop first (dead), then the Lithium (awake) and now it's running again (on the Eneloop) for a new record time (still working after about 30 minutes and I've tried switching it on/off several times), but I don't trust it at all. I mainly keep this light in my pocket as a backup, so I want to know it's reliable in case I find myself needing it.

I don't think it's a problem with the cell terminals not being the right size, because it was running on the same Eneloop cell for a couple of months without incident - it's just in the past week or so that it's started doing this. It never seems to just cut out when the light is engaged. It's only after you loosen the head and tighten it again, sometimes it doesn't come on.

Any ideas WTF might be going on here?

Well, it's just a late night stab at helping you ... perhaps there's condensation/moisture in the body or head. Perhaps try gentle use of hair dryer (don't overheat) and/or leave the tube open for several days in a dry place. Remove battery to maximize air circulation.

Keep us posted as events unfold. It's good experience to share. Better suggestions may follow.

I would simply send it back. It's defective.

Capn said:

Well, it's just a late night stab at helping you ... perhaps there's condensation/moisture in the body or head. Perhaps try gentle use of hair dryer (don't overheat) and/or leave the tube open for several days in a dry place. Remove battery to maximize air circulation.

Click to expand...

+1

That's my bet too... seems like condensation and as it dries out you are seeing a progression towards longer working times.
Hair dryer should work nicely or you could submerge the light in a bowl of uncooked (dry) rice and leave it there for a few days. Take the battery out...

Best of Luck, Cheers!

Utew said:

+1

That's my bet too... seems like condensation and as it dries out you are seeing a progression towards longer working times.

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Sounds semi-plausible, except that it's repeated the same pattern over the course of several days. If it were condensation I'd expect it to have dried out the first time and then just worked after that, assuming no corrosion or solute deposition. The light hasn't got wet either (not just recently, but never: it's only a few months old so I can say this with certainty), so I'm not sure how any significant moisture could have built up beyond the normal humidity of the air (which isn't that high here), but I suppose anything's possible. Also, due to some issues with my boiler, I have my central heating switched on constantly, on very low. That, plus good insulation, means I don't get the big temperature changes between morning and daytime that normally result in condensation forming. It hasn't been outdoors at all in the time it's been doing this.

I might try unscrewing it and leaving it on top of a radiator for a day, just in case it helps. At this point it might not prove anything though, because it's still working, for now. I'll be keeping a close eye on it and testing it regularly to see if the pattern changes again. I'll give it some more time for the fault to come back before trying the radiator thing. If it then makes the problem go away permanently, it's probably fair to assume condensation was the cause. At the moment it looks like it might have gone away on its own, but it's way to soon to know if that's permanent or temporary.

Yeah, I know... it's a semi-weak theory considering your experiences and now that you have elaborated on the conditions it has been kept in. Well there is always the possibility of a weak electrical connection somewhere. Keep your fingers crossed, that the ghost in the machine has been exorcised.

Thought I'd give an update to say I've been using the E05 SS as my usual EDC constantly since it stopped acting weird in January and the problem hasn't come back. So that's about 2 months without issue.

It's gradually become by far my single favourite light and the thoughts of possible reliability issues have now faded to the back of my mind. Whatever it was I'm going to assume it could have affected any light and it was just sheer bad luck to have had two distinct problems with the same light over a short space of time.

Would have been nice to have discovered the cause, but I guess we'll never know.

robert.t said:

Thought I'd give an update to say I've been using the E05 SS as my usual EDC constantly since it stopped acting weird in January and the problem hasn't come back. So that's about 2 months without issue.

It's gradually become by far my single favourite light and the thoughts of possible reliability issues have now faded to the back of my mind. Whatever it was I'm going to assume it could have affected any light and it was just sheer bad luck to have had two distinct problems with the same light over a short space of time.

Would have been nice to have discovered the cause, but I guess we'll never know.

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Thank you for the update - I'm glad it worked itself out for you; I have an E05SS on my keychain as my backup so this thread is indeed appreciated!

Grijon said:

Thank you for the update - I'm glad it worked itself out for you; I have an E05SS on my keychain as my backup so this thread is indeed appreciated!

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I settled on the E99 on my keyring, as I think it makes a better backup light, but I usually have the E05 SS in my jeans watch pocket: it's the one I usually reach for. It's also what I'll have on me around the house when I'm not carrying any keys.