Eagletac -> Two faulty (now dead) new T25C2 Pro's XHP35 HI D4's

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Two lights now dead.
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Was testing one light, all new Eagletac 3,500mAh cells, approx 2 hours of usage, mostly switching modes between tactical mode High > Med > Strobe. Then suddenly no output. Swapped batteries - dead. Swapped tailcaps - dead. Tried resetting back to default modes - dead. Even tried unprotected cells - dead. Sent back to vendor. Vendor and I thought it had to be a rare occurrence. That was 1 week ago.

Brand new replacement Light #2 - SAME STORY NOW TODAY. 2 defects in a row is definitely not a fluke and could indicate a production run of bad lights or faulty design. I also sent one to my bro and now I'm worried because he needs reliable illumination. Don't want his to fail when he needs it.

I did notice there was occasional audible modulation whine especially with the strobe but the cells where still around 70% capacity and the terminals CLEAN.

I'm thinking faulty circuit design for this high powered LED? Either way this has left a bad taste in my mouth.

Anyone know if the programming might have jammed and if there is a way to reset? Or definite hardware failure?

Any update on this? Two in a row seems very unlikely, unless there is a legitimate issue.

Also... does the "HI D4" automatically indicate the Neutral White HI emitter?

If you get the light working... I would love to see some outdoor beamshots.

I have the standard T25C2 HI neutral white and it's be 100% reliable. I haven't' heard any feedback from the Pro, other than this.

holygeez03 said:

Any update on this? Two in a row seems very unlikely, unless there is a legitimate issue.

Also... does the "HI D4" automatically indicate the Neutral White HI emitter?

If you get the light working... I would love to see some outdoor beamshots.

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Mine where D4's and indicated neutral tint. (and it was gorgeous when they where working)

As far as updates, Eagletac replied and are sending me a replacement dropin. Should arrive in a few weeks being it's coming out of China. We shall see.

markr6 said:

I have the standard T25C2 HI neutral white and it's be 100% reliable. I haven't' heard any feedback from the Pro, other than this.

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Do you switch modes often? How much runtime on the light so far? Also ever notice any regulation whine (a high pitched modulating buzzing sound). I seem to recall hearing this voltage regulation whine in the strobe before the light finally kicked.

Got a new XHP35 Hi neutral module from Eagletac (from China) and yep. After about two hours of use - it too has failed.

The light failed in mid use on the high setting. In hand. Cold weather environment 34 degrees.

I use all the settings, mostly medium, strobe is fun, and high occasionally.

So this makes it the 3rd Eagletac T25C2 Pro to fail in the passed two months. 3 in-a-row.

ledmitter_nli said:

Do you switch modes often? How much runtime on the light so far? Also ever notice any regulation whine (a high pitched modulating buzzing sound). I seem to recall hearing this voltage regulation whine in the strobe before the light finally kicked.

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Not often. Usually just a max output thrower for me. No whine thankfully since I can always pick that up on lights that do. I've had this for over 2 years and it's been reliable so far.

The XPH led modules have only been out since recent.

You are talking about an older model....

ledmitter_nli said:

The XPH led modules have only been out since recent.

You are talking about an older model....

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Yes, T25C2 HI neutral white mentioned in post 3 above.

markr6 said:

Yes, T25C2 HI neutral white mentioned in post 3 above.

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The neutral is freaking gorgeous (and obscenely bright) but darn, 3 failed lights. I SOO want to love Eagletac again. They HAVE to fix this.

As an extra data point, might be a good idea to list exactly what batteries you have been using, and what voltage they measured. May or may not have anything to do with the failure.

BTW, how does the optional 2 X 18650s work? Is there an extension tube?

terryoregon said:

As an extra data point, might be a good idea to list exactly what batteries you have been using, and what voltage they measured. May or may not have anything to do with the failure.

BTW, how does the optional 2 X 18650s work? Is there an extension tube?

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Using Eagletac 3500mAh 18650's. Brand new fully charged. Just to be sure even tried unprotected Panasonic 3400mAh 18650's. No dice.

As someone who worked in an electronics production environment for 37 years before retiring, here's my thoughts:

Although their lights may have passed all production tests, they likely were NOT doing a burn-in test where these failures would show up. Burn-in tests are expensive and time-consuming for production to perform, and usually aren't necessary for non-critical products. But NOW that they know there's an issue, they should issue a "stop ship", then pull warehouse stock and set-up a burn-in test (several hours) to determine root cause (or something similar - including analysis of the lights you send back).

terryoregon said:

As someone who worked in an electronics production environment for 37 years before retiring, here's my thoughts:

Although their lights may have passed all production tests, they likely were NOT doing a burn-in test where these failures would show up. Burn-in tests are expensive and time-consuming for production to perform, and usually aren't necessary for non-critical products. But NOW that they know there's an issue, they should issue a "stop ship", then pull warehouse stock and set-up a burn-in test (several hours) to determine root cause (or something similar - including analysis of the lights you send back).

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Strangely the vendor I ordered from says there have been no other returns for similar failures. And they have sold many of them. Maybe I'm switching too many modes or something. Or maybe I have the strangest black-streak probability on the flashlight roulette table. I haven't the foggiest idea.