Weird/interesting behavior from L2D

Hi all
Just got a Fenix L2D Q5 last night, and observed something interesting. As soon as I got it, I loaded it with Energizer lithium AAs. I decided to compare it to my P2D Q5 expecting similar performance. The L2D was waaaay brighter, and the difference between low and medium on the L2D was imperceptible. Meanwhile, the P2D stepped up through low, medium, and high, with definate increases in output. So, I swapped heads between the 2 lights, and this time both lights worked the way I originally expected, with almost identical output through all the modes. So I put the heads back on the lights they belong on and tried alkaline AAs, again both lights were nearly identical in performance. Weird! So, the L2D head is way brighter with 2 lithium AAs, than the P2D head with the same batts. From reading here, I thought the 2 heads were the same? What do you think is going on?

The energiser AA's have slightly higher voltage than alkies. I'd guess your emitter has a very low Vf, so the energisers DD the emitter. As soon as they've run down a bit and had the voltage drop, you should be fine and have all modes working. This is exactly the same effect as using a 3.7V rechargeable with these heads.

The P2D head probably has a higher Vf LED, so even at peak voltage of the energisers, this isn't enough to DD the emitter.

When I first got my Olight T25 I put Energizer lithiums in and couldn't see much difference between 2 of the modes. I was tired at the time and didn't think much of it. Next day I put rechargables in (ReCyko) and now I see the difference clearly. Maybe it was the same reason. :thinking:

Hello,

Look at CPF revieuws: http://www.cpfreviews.com/Fenix-L2DCE-Premium-Q5.php
It seems the L2D will behave normal again if fed with NiMH or alkaline.

Kind regards,
Joris

Interesting... I didn't know that! :ironic:

Thanks guys! That is along the lines that I was thinking. That the lithiums might have a little more voltage, and the emitters in the different heads might react differently due to tolerances. You guys really know your stuff.:bow:

burf151 said:

The L2D was waaaay brighter, and the difference between low and medium on the L2D was imperceptible.

Click to expand...

Mine is the same. Cannot really tell the difference between low and med. I guess I will try some NiMHs when I get home tonight.