Fenix LD01 - Low-Voltage Warning / Ramping Down?

[sween1911]

PLEASE NOTE: I have poured over many MANY Fenix LD01 threads on CPF, I cannot find a reference to my particular question...

I have a friend with a Fenix LD01. He LOVES it for EDC, but is having an issue, in his words "the light goes out with absolutely no warning".

I see a low-voltage warning listed on some ads for the LD01. What does that look like? blinking/ ramping down/ falling out of regulation? Do only newer model LEDs have this feature? Not sure which one he has. Could he have an older one that is missing this feature? Does the type of battery (alkaline/lithium/NiMH) negatively affect that feature? I know he was using Energizer lithiums at one point. There's got to be SOME noticable rampdown/change in brightness. Can you at least run it on low? Can you even get to low if the battery is too depleted to turn on?

Thanks in advance guys.

PS: Yes, my next recommendation to him is to join CPF.

 

[Hondo]

Sounds fishy. If you look at Selfbuilt's original L0D review, here: http://www.candlepowerforums.com/vb...-shootout-RUNTIMES-BEAMSHOTS-and-TEMPERATURES you see good regulation, followed by a sharp drop, but at least 10 minutes of diminishing "moon" level light to get you to a spare light/battery. In HKJ's review of a recent LD01 SS, here: http://www.candlepowerforums.com/vb...urements-and-outdoor-beamshots&highlight=LD01 you see the same. I have both of these, as well as an earlier LD01 SS with the XR-E emitter. I have never had a sudden death shut off due to low battery, like a first generation mini-Mag LED 2xAA will do. That is the only LED light I have owned, at least that I can recall, that has that kind of totally binary regulation.

NiMH batteries do better at giving full power until they are near exhausted, and will not have as much low light tail-off at the end as alkalines, but they still don't just die. Alkalines will have the most time in the dim region at the end of their life, but will fail to produce high level brightness for long, and may not ever get quite as bright as NiMH's since they just are not good at delivering high current. The best overall performance comes from lithium disposables from Energizer, but I still think they produce decent tails of diminishing brightness at the end, but they are costly.

Now, some people get this due to using Li-Ion cells with protection circuits. When the cell is run to the cut-off voltage of the cell, it goes open circuit, from bright light to darkness instantaniously. But there are not many protected AAA size (10440) Li-Ions out there yet, and you really are not supposed to use them in the LD01, although many have for the huge wow factor as it overdrives the light like crazy. The downside is loss of the low modes, as it runs in direct drive, and you can fry the boost circuit, so it will no longer be able to run on anything but Li-ions. Not to say there aren't reports from some of doing this for a long time with no ill effects, goes both ways.