Fenix LD20 and general LED issues

[Grapehunter]

I recently purchased a Fenix LD20, and thus far I loved it, but now my job requires that I have a flashlight that can stay on for an hour straight or longer at times without turning off.

The problem I've encountered with both the Fenix LD20 and a Maglite LED flashlight is after being on for 10+ minutes, the light would dim and eventually both the flashlights would shut off.

The Fenix LD20 would get pretty warm, and though I don't care about the heat, I do care a great deal about it's failure. I've tried fresh batteries but the result was the same. I could go back to a regular bulb flashlight which gets the job done but the LED flashlights are so much brighter that it's hard to downgrade.

My question is, is this a common problem among all LED flashlights?
and are there any solid recommendations out there for an LED flashlight that can stay on for over an hour with no falter?

My requirements would be:

- Compact size
- LED
- Uses AA Bateries
- Impact resistant
- Water Resistant/ Proof

 

[bbb74]

Which LD20 do you have? R4? I have the R4 and I run it for 40+ minutes on turbo and it has never shut off once on me.

I think some of the older models (not sure if older LD20 (Q5?) model or if it was the predecessor model) did have a 10 minute or so time limit.

 

[John_Galt]

What batteries are you using? If they're alkaline AA's, then this was to be expected.

Upgrade to either Energizer Lithium AA's, or Ni-MH rechargeable batteries. Alkalines have extremely low capacity in high current drain applications, and their extremely high internal resistance makes the voltage drop under load, which only makes the available current go down. So, the light thinks that the alky's are dead because of diminishing current drain, and dropping voltage, and it falls out of regulation.

The LD20 should have enough surface area to passively cool the LED, getting warm is actually a good thing in any high powered LED light, as it is a sign that there is a thermal pathway from the LED to the outer body.

 

[mcnair55]

Must admit never had a shutdown problem with any Led light before,whether it be a $ cheapy from fleabay or one from my collection.I have my Firecracker with a magnet super glued to the top hanging under my kitchen cupboard to light up my brew area when its dark and that is on for about 2 or 3 hours at a time every day,just pop a new battery in every couple of days or so.

 

[entoptics]

I'm guessing Galt has hit on the issue. Either that, or the OP has a defective light (which Fenix will surely replace).

I've done beamshot/runtime tests with Quark, EagleTac, iTP, and NiteCore lights, and have never experienced a shutdown or dimming due to heat. I've never done it with alkalines though. Only Rayovac LSD NiMH and Li-ion rechargeables.

If this problem is occurring with good NiMH rechargeable batteries (e.g. anything but Energizers), I'm guessing you have a faulty light. Send it back for replacement.

 

[Grapehunter]

It was indeed a battery issue. Switched to duracell nimh and now the flashlight stay on till the battery dies. Thanks for the responses